SERVICE MANUAL BOOK - 1 SERVICE MANUAL PUNCH CNG BSVI PHASE-2 SUPPLIMENT
Developed by: Technical Literature Cell. Release Date : May 2023 / First Edition. The information provided in this manual is based on the latest product information available at the time of publication. . C Copyright 2023 TATA MOTORS All rights reserved. The information in this manual shall not be reproduced or copied, in whole or in part, in any form without written permission from TATA MOTORS PASSENGER VEHICLES LTD. Vehicles are subject to modification in design, specification and equipment. Also refer the Service Circulars released by Customer Support about product & procedures.
INTRODUCTION This Supplement Service manual provides information pertaining to technical Specifications, repair, maintenance and overhaul of different aggregates fitted on TATA PUNCH CNG BSVI PHASE-2. All the data contained in this manual is based on the latest product information available at the time of publication and with the assumption that the person is well aware of general Automobile practices. This manual emphasizes the special features of the vehicle and thus benefits our workman, who is conversant with general Automobile practices. The contents which are not covered in this supplement service manual have to be read in conjunctions with “TATA PUNCH BSVI PHASE-2” Service manual. For ease of use, this workshop manual is divided into 4 volumes, comprising several sections. Each aggregate has a separate section. THE BOOK– 1 CONTAINS 1.2L REVOTRON NGNA CNG BSVI PHASE 2 ENGINE ELECTRICAL THE BOOK– 2 CONTAINS DIAGNOSTIC TROUBLE SHOOTING CODES (DTC) THE BOOK– 3 CONTAINS SERVICE SCHEMATICS THE BOOK– 4 CONTAINS INFO. FITMENT DRAWINGS
PUNCH CNG BSVI PHASE 2 SUPPLEMENT TABLE OF CONTENT SR. NO. AGGREGATE 1 1.2L REVOTRON NGNA CNG BSVI PHASE 2 ENGINE 2 ELECTRICAL
ENGINE 1.2L REVOTRON CNG PHASE-2 ENGINE
TABLE OF CONTENTS 1. GENERAL INFORMATION ........................................................................................................................1 A. ENGINE INTRODUCTION ..................................................................................................................1 B. ELECTRONIC FUEL INJECTION CONTROL .....................................................................................3 C. TECHNICAL SPECIFICATION ............................................................................................................4 D. SPECIAL TOOLS .................................................................................................................................5 E. ASSEMBLY CLEARANCES.................................................................................................................9 F. SEALANTS .........................................................................................................................................10 G. LEAKAGE RATES..............................................................................................................................10 H. RECOMMENDED LUBRICANTS & COOLANTS ..............................................................................10 2. TROUBLESHOOTING..............................................................................................................................11 3. CONSTRUCTIONAL AND SERVICE DETAILS.......................................................................................17 A. ENGINE LIFTING ..............................................................................................................................17 B. INTAKE MANIFOLD...........................................................................................................................18 C. CYLINDER HEAD COVER ................................................................................................................20 D. CYLINDER HEAD-A ..........................................................................................................................22 E. CYLINDER HEAD-B ..........................................................................................................................24 F. CYLINDER BLOCK ...........................................................................................................................25 G. OIL SUMP...........................................................................................................................................27 H. MOVING PARTS................................................................................................................................29 ENGINE TIMING ...............................................................................................................................32 I. J. EXHAUST MANIFOLD.......................................................................................................................34 K. CNG FUEL INJECTION EQUIPMENT...............................................................................................35 L. FUEL INJECTION EQUIPMENT........................................................................................................36 M. LUBRICATION PUMP AND COMPONENTS.....................................................................................37 N. AIR INTAKE SYSTEM........................................................................................................................39 O. SPECIAL INSTALLATION...................................................................................................................41 P. ENGINE SUSPENSION.....................................................................................................................44 Q. CNG SYSTEM....................................................................................................................................46 4. ENGINE TESTS AND MAINTENANCE ...................................................................................................48 A. PRELIMINARY INSPECTION ...........................................................................................................48 B. ENGINE TESTS ................................................................................................................................49 ENGINE COMPRESSION TEST ................................................................................................49 I. ENGINE OIL CONSUMPTION TEST :.........................................................................................50 II. 1.2L REVOTRON CNG PHASE-2 ENGINE
ENGINE OIL PRESSURE TEST ................................................................................................51 III. C. REGULAR MAINTENANCE...............................................................................................................52 ENGINE OIL AND FILTER CHANGE :.........................................................................................52 I. ENGINE COOLANT REPLACEMENT :.......................................................................................54 II. AIR FILTER ELEMENT REPLACEMENT: ...................................................................................58 III. SPARK PLUG REPLACEMENT :................................................................................................59 IV. V. AIR CONDITIONER COMPRESSOR AND ALTERNATOR BELT REPLACEMENT :..................60 VI. RECEPTACLE VALVE O RING REPLACEMENT ON VEHICLE................................................61 RECEPTACLE VALVE FILTER MESH REPLACEMENT...........................................................62 VII. CNG FILTER REPLACEMENT..................................................................................................63 VIII. BI-FUEL AUTO SWITCH STRATEGY.........................................................................................66 IX. 5. REPAIR AND INSPECTION DETAILS.....................................................................................................68 A. ACCESSORY DRIVING BELT:...........................................................................................................68 B. TIMING CHAIN :.................................................................................................................................68 C. CYLINDER HEAD: .............................................................................................................................68 D. VALVES :............................................................................................................................................69 E. CYLINDER HEAD VALVE SEATS :....................................................................................................70 F. ROLLER FINGER FOLLOWER .........................................................................................................70 G. HYDRAULIC LASH ADJUSTER (HLA)..............................................................................................71 H. CAMSHAFTS (INTAKE & EXHUAST) ...............................................................................................71 PISTON AND PISTON RINGS :.........................................................................................................72 I. J. CONNECTING RODS :......................................................................................................................73 K. CRANKSHAFT :.................................................................................................................................74 L. CRANK CASE....................................................................................................................................75 M. FUEL TANK .......................................................................................................................................75 N. CANISTER PURGE VALVE................................................................................................................76 O. CANISTER .........................................................................................................................................76 6. ENGINE SYSTEM.....................................................................................................................................78 A. AIR INTAKE SYSTEM .......................................................................................................................78 B. BLOW BY SYSTEM ...........................................................................................................................80 C. LUBRICATION SYSTEM :..................................................................................................................81 D. EXHAUST SYSTEM...........................................................................................................................85 E. COOLING SYSTEM :.........................................................................................................................87 F. FUEL SYSTEM :.................................................................................................................................90 G. CNG FUEL SYSTEM LAYOUT...........................................................................................................93 1.2L REVOTRON CNG PHASE-2 ENGINE
H. SCHEMATIC DIAGRAM OF CNG INJECTION SYSTEM..................................................................94 CNG FUEL SYSTEM COMPONENTS...............................................................................................99 I. 7. ENGINE ON VEHICLE SERVICE PROCEDURE...................................................................................104 A. ENGINE REMOVAL AND REFITMENT ..........................................................................................104 B. AIR FILTER ASSEMBLY REMOVAL.................................................................................................110 C. FUEL RAIL AND INJECTOR ............................................................................................................111 D. SPARK PLUG REMOVAL.................................................................................................................112 E. EXHAUST SYSTEM REMOVAL.......................................................................................................112 F. FUEL SYSTEM.................................................................................................................................117 G. COOLING SYSTEM.........................................................................................................................122 H. COMPRESSOR AND ALTERNATOR BELT REMOVAL...................................................................126 TIMING CHAIN REMOVAL...............................................................................................................127 I. J. WATER PUMP..................................................................................................................................131 K. SOLENOID ......................................................................................................................................132 L. ELECTRONIC THROTTLE BODY...................................................................................................133 M. STARTER MOTOR...........................................................................................................................133 N. ALTERNATOR ..................................................................................................................................134 O. COMPRESSOR................................................................................................................................134 P. INJECTION SYSTEM.......................................................................................................................135 Q. CNG FUEL SYSTEM........................................................................................................................138 R. MOON VALVE REMOVAL / REPLACEMENT PROCEDURE..........................................................146 S. HIGH PRESSURE LINE...................................................................................................................156 T. FUEL FILLER BOWL........................................................................................................................157 U. FUEL FLAP SWICTH .......................................................................................................................159 8. ENGINE OVEHAULING (ON OVERHAUL STAND)..............................................................................161 A. ENGINE DIS-ASSEMBLY.................................................................................................................161 REMOVAL OF INTAKE MANIFOLD ..........................................................................................161 I. REMOVAL OF EXHAUST MANIFOLD ......................................................................................162 II. REMOVAL OF OIL SUMP..........................................................................................................164 III. REMOVAL OF SENSORS.........................................................................................................164 IV. V. REMOVAL OF ACCESSORIES.................................................................................................165 VI. REMOVAL OF TIMING CHAIN..................................................................................................168 REMOVAL OF CYLINDER HEAD AND CAMSHAFT...............................................................170 VII. REMOVAL OF CYLINDER HEAD SUB-ASSEMBLIES...........................................................171 VIII. REMOVAL OF CYLINDER BLOCK SUB-ASSEMBLIES...........................................................173 IX. 1.2L REVOTRON CNG PHASE-2 ENGINE
B. ENGINE ASSEMBLY........................................................................................................................176 ASSEMBLY OF CYLINDER BLOCK SUB-ASSEMBLIES.........................................................176 I. FITMENT OF PISTON AND CONNECTING ROD SUB-ASSEMBLIES ....................................181 II. ASSEMBLY OF CYLINDER HEAD SUB-ASSEMBLIES...........................................................184 III. ASSEMBLY OF CYLINDER HEAD...........................................................................................185 IV. V. ASSEMBLY OF ENGINE TIMING CHAIN..................................................................................187 VI. ASSEMBLY OF ACCESSORIES DRIVING BELT.....................................................................192 ASSEMBLY OF SENSORS AND PERIPHERALS ...................................................................193 VII. ASSEMBLY OF OIL SUMP......................................................................................................194 VIII. ASSEMBLY OF EXHAUST MANIFOLD....................................................................................195 IX. X. ASSEMBLY OF INTAKE MANIFOLD ........................................................................................197 9. ENGINE MANAGEMENT SYSTEM.......................................................................................................199 A. ABBREVIATIONS .............................................................................................................................199 B. AN OVERVIEW ...............................................................................................................................199 C. ELECTRONIC CONTROL UNIT (ECU)............................................................................................201 D. SENSORS ........................................................................................................................................207 MANIFOLD AIR PRESSURE SENSOR AND TEMPERATURE SENSOR (T-MAP) :................208 I. LAMBDA SENSOR ...................................................................................................................209 II. CAMSHAFT POSITION SENSOR ............................................................................................213 III. KNOCK SENSOR .....................................................................................................................214 IV. V. CRANKSHAFT POSITION SENSOR .......................................................................................215 VI. COOLANT TEMPERATURE SENSOR ....................................................................................217 E. ACTUATORS ....................................................................................................................................218 IGNITION COIL .........................................................................................................................218 I. SOLENOID VALVE (OIL CONTROL VALVE).............................................................................220 II. FUEL INJECTORS ....................................................................................................................221 III. PURGE CONTROL VALVE ......................................................................................................222 IV. V. ELECTRONIC THROTTLE BODY ............................................................................................223 F. SWITCH ...........................................................................................................................................225 OIL PRESSURE SWITCH .........................................................................................................225 I. THROTTLE PEDAL SENSOR ..................................................................................................226 II. CLUTCH SWITCH ....................................................................................................................227 III. BRAKE SWITCH ......................................................................................................................228 IV. V. WHEEL SPEED SENSOR.........................................................................................................229 1.2L REVOTRON CNG PHASE-2 ENGINE
1. GENERAL INFORMATION A. ENGINE INTRODUCTION Description: The “1.2L REVOTRON” is a 1200 CC, 3-Cylinder Gasoline Engine, with MPFI, VCTi and BSVI Ph2 compliant CNG Twin CYlinder. Features: Stiffened Aluminium Crankcase with Aluminium bed plate structure. • Double Overhead Camshaft (DOHC) with 4 valves per cylinder. • Variable cam timing - Dual VCT (VCTi) • Timing chain drive system • Three stage oil pump • 1.2L REVOTRON CNG PHASE-2 ENGINE 1
Weight optimized hollow cam shafts • Drive by wire technology (Electronic Throttle Control). • Plastic intake manifold and head cover • Light weight piston assembly • Auto tensioner auxillary belt drive system • Engine is BSVI OBD-II compliant. • Advance Engine Management System from M/s BOSCH providing precise control for performance and • emissions. Multi Point Fuel Injection (MPFI). • Graded bearing system for Main bearing and con-rod big end. • 1.2L REVOTRON CNG PHASE-2 ENGINE 2
B. ELECTRONIC FUEL INJECTION CONTROL The engine management software in the vehicle’s Engine Control Unit (ECU) controls the fuel injection and ignition system using a variety of sensors that provides the engine operating conditions and operates input information. The ECU includes self-diagnosis to help pinpoint any system malfunctions. Refer to the “Engine Management System” portion of this section for additional information. The MPFI type of fuel injection offers many advantages over a single point fuel injection system or a carburetor engine. The following paragraphs describe the advantages of the electronic fuel injected engine. Improved Engine Performance : • The ECU precisely and instantly controls optimum fuel delivery and spark timing according to the operating conditions, inputs from the engine sensors, and operator input. This control improves vehicle response and acceleration. Increased Fuel Economy : • The electronic fuel injection system allows the REVTRN20 engine to be Bharat Stage VI (BSVI Ph2) compliant. By electronically controlling the air/fuel ratio of the combustion process, the engine maintains an air/fuel closer to stoichiometric (14.7:1, air to fuel), the optimum ratio for complete combustion of the fuel mixture. Decreased Exhaust Emissions : • The use of electronic fuel injection also decreases exhaust emissions because the air/fuel ratio is precisely controlled through the ECU for operating conditions and driver input. The catalytic convertor also helps reduce exhaust emissions and specially manufactured to the fuel injection system’s operation. Improved Cold Starting and Operation : • By detecting the atmospheric and engine conditions in which the operator is starting and driving the vehicle, the ECU can adjust fuel mixture and ignition timing to help the vehicle start more easily when cold and to warm up faster. The MPFI ECU achieves all of these advantages by instantly compensating for changes in operating conditions and sensors inputs. This compensation is faster and more efficient than a mechanical system or human input. 1.2L REVOTRON CNG PHASE-2 ENGINE 3
C. TECHNICAL SPECIFICATION Model 1.2L NG NA REVOTRON Description REVOTRON 1.2L NA Gen1 Plus CNG Engine, BSVI Phase - 2 Type Bi-fuel CNG 4-stroke MPFI, inline 3 cylinder with 4 valves per cylinder Engine Configuration Transverse mounted inline 3-cylinder engine Engine Management System BOSCH Engine Management System Bore/Stroke 77 mm X 85.8 mm Engine Capacity 1199 cc Radiator Coolant Water + Ethylene Glycol 60:40 Compression Ratio 11.3 Maximum Engine Power Output Petrol: 63 kw @ 6000 rpm (85ps @ 6000 rpm) CNG : 54 kw @ 6000 rpm (70ps @ 6000 rpm) Maximum Engine Torque Output Petrol :113 Nm @ 3300 +/- 200 RPM CNG: 95 Nm @ 3500 +/ -100 RPM Engine Firing Order 1-2-3 Oil Capacity 3.5 L Cooling System Capacity 4 liters Spark Plug Type FM : RER8MC (0.8 to 0.9 mm gap) Air Filter Dry (paper) type Oil Filter Spin on Full flow Paper type Fuel Filter In line filter (Integrated with Fuel pump in tank ) + CNG Filter Timing Chain Drive VCT DENSO Controller Assy Emission Norms Bharat Stage VI Phase-2 Compliance Ignition Coil Details Epoxy Potted Coil Type Ignition Coil (Supply Voltage 5-16V) CNG tank capacity 30 liters Water capacity (each cylinder) Total 60 liters capacity CNG Filter Maximum pressure: 450kPa Nominal gas pressure: 400kPa 1.2L REVOTRON CNG PHASE-2 ENGINE 4
D. SPECIAL TOOLS SR NO. TOOL DESCRIPTION TOOL PART NUMBER APPLICATION 1 Engine Support fixture 5123 5890 2601 2 Stand-Engine Support 5424 5890 2401 3 Overhauling stand 5425 5890 0605 4 Bracket LHEngine Overhauling stand 5424 5890 2403 1.2L REVOTRON CNG PHASE-2 ENGINE 5
SR NO. TOOL DESCRIPTION TOOL PART NUMBER APPLICATION 5 Bracket RHEngine Overhauling stand 5424 5890 2402 6 Adapter 5438 5890 2403 7 Pin-Flywheel locking In Standalone Condition 2868 5890 0604 8 Pin-Flywheel locking On vehicle 5424 5890 0607 9 Pin-Timing chain tensioner plunger locking 5424 5890 0604 1.2L REVOTRON CNG PHASE-2 ENGINE 6
SR NO. TOOL DESCRIPTION TOOL PART NUMBER APPLICATION 10 Wedge-Oil Sump sealant cutting 5424 5890 0609 11 CompressorValve spring 2829 5890 0605 12 Rail - Valve spring compressor 5424 5890 0606 13 Drift-Crank shaft rear oil seal 2699 5890 1803 14 Drift-Crank shaft front cover oil seal 2654 5890 0508 15 Spanner-Oil filter 5424 5890 1802 1.2L REVOTRON CNG PHASE-2 ENGINE 7
SR NO. TOOL DESCRIPTION TOOL PART NUMBER APPLICATION 16 Guide pin for VCT 5424 5890 0614 17 Engine adaptor for Compression Test Refer tool ITCC7337 18 CNG cylinder valve removal 5442 5890 47 01 19 NO GO Gauge for HP tube joint inspection 2873 5890 47 03 1.2L REVOTRON CNG PHASE-2 ENGINE 8
E. ASSEMBLY CLEARANCES GROUP DESCRIPTION VALUES (MM) 01 Crankshaft Axial Play 0.1 To 0.3 Main Bearing Clearance (Cold Condition) 0.013 To 0.046 Cylinder Head Gasket Compression 0.7 THK (In assembled condition) Balancer Shaft Axial play 0.1 to 0.25 Balancer Shaft Bearing clearance (Assembled condition) 0.02 to 0.046 03 Connecting Rod Axial Play (Big End) 0.05 To 0.35 Piston Play Clearance On Skirt (Bore To Piston Stamp Size) 0.055 To 0.075 Connecting Rod Bearing Clearance (Small End) (Cold Condition) 0.005 To 0.025 Connecting Rod Bearing Clearance (Big End) (Cold Condition) 0.027 To 0.066 Piston Topping (Piston Is Above Block Top Face) 0.19 ± 0.1 05 Camshaft Axial Play 0.1 To 0.3 Camshaft Bearing Clearance 0.04 To 0.082 Valve Stem Clearance, Inlet 0.017 To 0.043 Valve Stem Clearance, Exhaust 0.027 To 0.053 1.2L REVOTRON CNG PHASE-2 ENGINE 9
F. SEALANTS G. LEAKAGE RATES H. RECOMMENDED LUBRICANTS & COOLANTS SEALANT NO. SEALANT TYPE USE 56506005162 Adhesive Sealant Loctite 5188 Henkel For Sealing Block To Bed Plate 56506005162 Adhesive Sealant Loctite 5188 Henkel For Plug Mc 10x1 56506002350 Adhesive Bearing Retainer Hs Ts25408 For Core Plug 56506002350 Adhesive Bearing Retainer Hs Ts25408 For Vent Tube-Cyl Head 570501995303 Sealant Loctite 5910 (50 Ml. Tube Pack) For Oil Sump To Bedplate 570501995301 Sealant Loctite 5060 (50 Ml. Tube Pack) For Crank Sensor REGION PRESSURE LEAKAGE (MAX.) Air Side 0.2 bar < 200 cc/min Water Side 0.7 bar < 20 cc/min ITEM SPECIFICATION COMPANY AND BRAND QTY ENGINE OIL 0W20 LOW ASH BS VI SS6588 CASTROL - Magnatec Professional T 0W20 PETRONAS TATA MOTORS Genuine Oil – Engine Oil Synth 0W20 EXXON MOBIL - Mobil super 3000 TMGO 0W20 Tata motors genuine oil 3.5 Litres COOLANT (Pre-mixed) (Antifreeze agent : Soft water = 40 : 60 ratio) Class II/JIS K2234 TATA SS7700S1 SUNSTAR CCI - Golden Cruiser LLC 2200NP CASTROL - Castrol Radicoolant SFO Premix 4 Litres 1.2L REVOTRON CNG PHASE-2 ENGINE 10
2. TROUBLESHOOTING Starting Problems Condition Possible Cause Remedy Engine does not crank Insufficient battery voltage/charge test battery and charging system. Clean and tighten battery • connections. Jump start engine. • Battery or charging system • component faulty. Replace as necessary. Engine starter motor defective. Repair or replace starter as • necessary. Immobilizer system defective. (as equipped) Inspect system and repair as • necessary. Engine components seized. Inspect engine components for • seizure. Attempt to rotate crankshaft by hand. • Overhaul engine as necessary. • Fuses blown out (if any) Check for blown fuse. Replace the • fuses if damaged. Engine cranks but does not start Obstructed air filter or air inlet. Clean or replace air filter or inlet. • Incorrect valve/ignition timing or timing belt broken. Check timing system components • and repair or replace as necessary. Faulty spark plugs, wires or ignition coil. Check ignition system components • for proper operation. Replace as necessary. Malfunctioning engine management system component. (exhaust sensors and actuators) Perform engine management system • diagnostic test as described in this section of the manual. Defective Engine Control Unit (ECU) Replace as necessary. • Malfunctioning emissions system component. Check tank pressure valve, purge • canister valve and charcoal canister. Repair or replace as necessary. Clogged or faulty fuel filter, fuel regulator, fuel line or fuel pump. Check fuel system components, • repair or replace as necessary Clogged or faulty fuel injectors Check fuel injector operation. • Replace as necessary. Improper firing order Check ignition system and fuel • injector connections. Rectify as necessary. Inertia switch tripped or defective. Reset or replace as necessary. • Engine Starts but does Faulty ETC unit. 1.2L REVOTRON CNG PHASE-2 ENGINE 11
not idle Perform Diagnosis test. Replace as • necessary. Fuel filter if clogged. Replace the fuel filter. • Fuel lines are pinched or clogged Correct the routine to avoid pinch, or • allow shop air to clear the clog in the fuel lines. Improper Electrical supply at pump connector If electrical supply is in proper check • electrical system. In adequate fuel pump pressure IF fuel pump does not built pressure • then replace. Incorrect manifold absolute pressure (MAP) sensor signal input. Check for leakage at sensor. • Perform diagnostic test. • MIL & SIL check Check using diagnostic tool for MIL & • SIL. Take corrective action. Defective EMS unit Check using diagnostic tool. Take • corrective action. Engine idles erratically Disconnected or leaking vacuum line or vacuum leak at inlet manifold. Inspect all vacuum lines and • connections. Repair or replace as necessary. Faulty ETC unit. Perform diagnostic test. Replace as • necessary. Incorrect valve / ignition timing. Check timing system components • and repair or replace as necessary. Fuel filter if clogged. Replace the fuel filter. • fuel lines are pinched or clogged Correct the routine to avoid pinch, or • allow shop air to clear the clog in the fuel lines. Improper Electrical supply at pump connector If electrical supply is in proper check • electrical system. In adequate fuel pump pressure IF fuel pump does not built pressure • then replace. Incorrect MAP sensor signal Check and replace if necessary. • Defective EMS ECU Check using diagnostic tool. Take • corrective action. Clogged injector Check for clogged injector. Take • corrective action. Poor Engine Performance Condition Possible Cause Remedy Maximum RPM -low Insufficient battery voltage/charge - 1.2L REVOTRON CNG PHASE-2 ENGINE 12
test battery and charging system. Clean and tighten battery • connections Jump start engine. • Battery or charging system • component faulty. Replace as necessary. Obstructed air filter or air inlet Clean or replace air filter or inlet. • Improper grade or contaminated fuel Rush fuel system with fresh, clean, • fuel of the correct type. Replace fuel filter. Faulty spark plugs, wires, or ignition coil Check ignition system components • for proper operation. Replace as necessary. Malfunctioning engine management system component Perform engine management system • diagnostic test as described in this section of the manual. Fuel filter if clogged. Replace the fuel filter. • fuel lines are pinched or clogged Correct the routine to avoid pinch, or • allow shop air to clear the clog in the fuel lines. Improper Electrical supply at pump connector If electrical supply is in proper check • electrical system. In adequate fuel pump pressure IF fuel pump does not built pressure • then replace. Incorrect crank angle signal Check sensor gap and adjust to 1.0 • ± 0.4mm Clogged or faulty fuel injector(s) Check fuel injector operation. • Replace as necessary. Improper firing order Check ignition system and fuel • injector connections. Rectify as necessary. 1.2L REVOTRON CNG PHASE-2 ENGINE 13
CNG SYSTEM TROUBLE SHOOTING SR. NO. PROBLEM CAUSE SOLUTION 1 Engine missing on CNG and runs well on petrol. Inadequate CNG supply. Check if filter is blocked or high pressure line is blocked. Ignition System faulty. Check spark plug and ignition coil Air filter dirty. Clean air filter Wiring harness Check injector wiring harness connections for proper latching, terminal loosening. Rectify Regulator Vacuum port blocked. Clear regulator vacuum port. 2 Poor pick up. (CNG Mode) Air filter dirty. Clean air filter Ignition system faulty Check and Rectify CNG Injector faulty Replace injector Pressure Regulator Faulty Check gas delivery, replace regulator if needed 3 Under-filling/no filling of gas into cylinder Receptacle filter mesh damaged or clogged Replace the filter mesh Receptacle o ring defective/missing Replace the o ring/fit new o ring Receptacle non return valve faulty Replace the receptacle Incorrect CNG filling gun To visit another CNG pump Incorrect CNG filling pressure To visit another CNG pump 4 CNG regulator not delivering gas Manual valve closed Open manual valve Solenoid not operating. Check operation. Replace regulator if found faulty HP line blocked Check for blockage. Clean using compressed air if blockage is found. Pressure Regulator Faulty Check and Replace 5 CNG Leakage Leakage from joints/components due to inadequate or no sealing Check and tighten the joints 6 CNG smell in passenger cabin Leakage from filler valve/ receptacle or cylinder valve joints Check and tighten the joint. Venting system blocked Check and clear blockage 1.2L REVOTRON CNG PHASE-2 ENGINE 14
SR. NO. PROBLEM CAUSE SOLUTION 7 Pressure Regulator freezing Inadequate coolant circulation Check the coolant circuit for damage or leakage. Blockage in coolant circuit Check and rectify CNG leakage Check and Rectify Coolant circuit leakage Check heater hose and joints Radiator circuit faulty Check radiator circuit 8 Leakage from end connection High pressure connection not proper. Tighten the fitting nut as per the standard instruction for the high pressure connection. 9 O-ring found damage condition Dirt particles in gas or damage due to continuous usage. Change the O-ring as per the maintenance procedure. 10 Leakage from Cylinder valve threads Over Tightening In case of over tightening the valve threads will be damaged. Replace the valve with a new one and install as per given instructions Teflon tape is not properly wrapped Or incorrect grade of Teflon tape Unwrap the Teflon tape and Apply Teflon tape layers on threaded neck of cylinder valve in clock wise direction (Swagelok make Teflon tape 12.7 mm width (Swagelok part number: MS-STR-8) is recover and no of turns should be minimum 6) Do not re-use the same tape as removed during dismantling of joint. 11 Pressure Release Device/Valve Activated Cylinder subjected to high pressure/temperature Replace the Cylinder valve with a new one. Do not attempt to repair or re-use the faulty valve. 12 Gas is not coming from Cylinder Excess flow device activated due to pressure difference 1. Close the manual valve and wait for a few minutes. 2. Open the knob of the manual valve slowly. 13 CNG level show erratic reading on cluster /Gasoline to CNG mode not converting Pressure regulator sensor failure Replace the pressure regulator sensor Both or One of the Manual shut off valve may be closed Open the manual shut off valve/s if found in closed condition 1.2L REVOTRON CNG PHASE-2 ENGINE 15
SR. NO. PROBLEM CAUSE SOLUTION Check CNG Level on instrument cluster is it shows empty Refill CNG if level shows empty. Pressure regulator freezing due to inadequate coolant circulation, coolant hose damage, blockage or leakage Check the coolant circuit for damage, blockage or leakage CNG gas leakage Check all joints and rectify 1.2L REVOTRON CNG PHASE-2 ENGINE 16
3. CONSTRUCTIONAL AND SERVICE DETAILS A. ENGINE LIFTING Engine Lifting : SR NO DESCRIPTION NO REUSE SEALA NT LUBRICATI ON TORQUE (KGF.M) 1 Engine Lifting Hook (Front) 2 H/FL Screw M8X18 (Lifting Hook Front) 2.0+0.3 3 Engine Lifting Hook (Rear) 4 H/FL Screw M8X18 (Lifting Hook Rear) 2.0+0.3 5 HEX FLANGE SCREW M6X14 2.0+0.3 1.2L REVOTRON CNG PHASE-2 ENGINE 17
B. INTAKE MANIFOLD 1.2L REVOTRON CNG PHASE-2 ENGINE 18
Note:- This Symbol indicates critical tightening torque. SR NO DESCRIPTION NO REUSE SEALANT LUBRICATION TORQUE (KGF.M) 1 HEX FL BOLT M6X40 (4 Qty) 1 + 0.2 2 Electronic Throttle Control 3 Intake Manifold 4 PRESSURE/TEMPERATURE SENSOR (MAP SENSOR) 1 + 0.2 5 HEX FL SCREW M6X12 6 HEX FL NYLOC NUT M8 2.0+0.3 7 HEX FL SCR M8X14 1 + 0.2 8 STUD CM8X30 2.5 9 H/FL BOLT M8X28 1 + 0.2 10 BRACKET INTAKE MANIFOLD SUPPORT 11 BRACKET INTAKE MANIFOLD SUPPORT 12 H/FL BOLT M8X28 2 13 BRACKET THROTTLE 14 Gasket (Intake Manifold) (3 Nos) 15 Gasket (For Electronic Throttle Control) 1.2L REVOTRON CNG PHASE-2 ENGINE 19
C. CYLINDER HEAD COVER 1.2L REVOTRON CNG PHASE-2 ENGINE 20
Note:- • This Symbol indicates critical tightening torque. SR NO DESCRIPTION NO REUSE SEALANT LUBRICATION TORQUE (KGF.M) 1 Hex FL Bolt M6X25 for Ignition Coil (3Qty) 1.0 ±0. 2 2 Ignition Coil (3Qty) 3 Cylinder head Cover 4 Gasket (Cylinder Head Cover)** 5 Hex. Bolt (Cylinder Head) (8Qty)• 5 + 180˚ 6 Washer 7 Gasket (Cylinder Head) 8 Dipstick 9 ‘O’ Ring (Oil Filler Cap) 10 Hex. FL Screw M6X22 (Head Cover) (13Qty) 1.0 11 Oil Filler Cap 12 Solenoid Valve 13 Hex FL Nut AM6 for Solenoid valve (1Qty) 1.0 14 Stud C M6X20 for OCV 1.0 1.2L REVOTRON CNG PHASE-2 ENGINE 21
D. CYLINDER HEAD-A 1.2L REVOTRON CNG PHASE-2 ENGINE 22
Note:- • This Symbol indicates critical tightening torque. SR NO DESCRIPTION NO REUSE SEALANT LUBRICATION TORQUE (KGF.M) 1 Hex FL Bolt M6X60 for ITG Bearing Cap Upper (4 Qty)• 1.5±0.15 2 ITG Bearing Cap Upper 3 Camshaft 4 ITG Bearing Cap Lower 5 Cylinder Head 6 Exhaust Valve 7 Intake Valve 8 Camshaft Bearing Cap (Inner) 9 H/FL Bolt M6X35 for Camshaft Brg. Cap (12 Qty)• 1.5 10 Dowel Bolt M6X35 for Camshaft Brg. Cap (12 Qty)• 1.5 11 Spring Seat 12 Valve Guide Seal 13 Valve Spring 14 Valve Spring Retainer 15 Lock Half 16 HLA RFF Assembly 1.2L REVOTRON CNG PHASE-2 ENGINE 23
E. CYLINDER HEAD-B Cylinder Head-B SR NO DESCRIPTION NO REUSE SEALANT LUBRICATION TORQUE (KGF.M) 1 Seal Plug M10X1 for Oil Gallery 2.0 + 0.3 2 Oil Pressure Switch 3 3 Coolant Temperature Sensor 3.5 4 H/FL Screw M6X14 for Cam Sensor 0.4 + 0.1 5 Cam Phase Sensor 1.2L REVOTRON CNG PHASE-2 ENGINE 24
F. CYLINDER BLOCK Note:- • This Symbol indicates critical tightening torque. 1.2L REVOTRON CNG PHASE-2 ENGINE 25
SR NO DESCRIPTION NO REUSE SEALANT LUBRICATION TORQUE (KGF.M) 1 Seal Plug M20x1.5 for oil gallery crankcase 2.5 2 Crankcase 3 Knock Sensor 4 Hex FL Screw M8X30 2.0+0.5 5 Sealing Plug M24X1.5 3.5 6 Crankshaft Oil Seal (Rear) 7 Hex FL Bolt M8X70 (8Qty) 3.2+0.6 8 Bed plate MB bolt M10 (10 Qty) • 5.0±0.5 120˚±15˚ 9 Bed Plate 10 Crank Angle Sensor 11 H/FL Screw M6X22 for Crank Angle Sensor 1.0+0.2 12 Deflector Plate Cyl. Block 13 Hollow Dowel,12H6 x10.6 x 12L 14 Hex FL Bolt M8x35 1.0 ± 0.1, 45˚ ± 5˚ 15 Balancer Mass 16 Cylindrical Pin 17 Balancer Shaft 18 Thrust Washer 19 CSK Socket Screw M6x20 (2 Qty) 1.2 – 1.5 20 Gear, Balancer Shaft 21 H/FL Bolt M12x45 5.0 ± 0.5, 45˚ ± 5˚ 1.2L REVOTRON CNG PHASE-2 ENGINE 26
G. OIL SUMP 1.2L REVOTRON CNG PHASE-2 ENGINE 27
SR NO DESCRIPTION NO REUSE SEALANT LUBRICATION TORQUE (KGF.M) 1 Oil Sump 2 Sealing Washer 3 Drain Plug 3.5 4 H/FL Screw M6X14 for Oil Sump (18 Qty) 0.8 5 Pipe seal 6 Water Bypass Assembly 7 H/FL Screw M6X14 1 + 0.2 1.2L REVOTRON CNG PHASE-2 ENGINE 28
H. MOVING PARTS Note:- • This Symbol indicates critical tightening torque. 1.2L REVOTRON CNG PHASE-2 ENGINE 29
SR NO DESCRIPTION NO REUSE SEALANT LUBRICATION TORQUE (KGF.M) 1 Top Ring 2 Taper Faced Ring 3 Oil Ring 4 Piston Pin 5 Round Wire Circlip 6 Connecting Rod 7 Bearing Half (Connecting Rod) 8 Bolt (Connecting Rod) (M8 X 1) (6 Qty)• 2.2+0.5 90˚ ± 5˚ 9 Woodruff Key 10 Crank Sensor Target Wheel 11 Assembly Vibration Damper Pulley 12 Washer (Damper Pulley) 13 Hex. Bolt M16x1• 14.5+0.3 90˚ ± 5˚ 14 CSK SOC Screw M6X20 for crank sensor wheel 1.7+0.3 15 Bearing Shell Half Lower (Crankshaft) 16 Bearing Shell Half Upper (Crankshaft) 17 Thrust Washer 18 Crankshaft 19 Flywheel 20 Hex. Bolt For Flywheel (M10 X 1.5) (6 Qty)• 3.5+0.5 25˚ ± 5˚ 21 Piston 22 Cylindrical Pin 1.2L REVOTRON CNG PHASE-2 ENGINE 30
SR NO DESCRIPTION NO REUSE SEALANT LUBRICATION TORQUE (KGF.M) 23 Gear, Crankshaft 24 Cylindrical Pin 25 Bush 1.2L REVOTRON CNG PHASE-2 ENGINE 31
ENGINE TIMING I. 1.2L REVOTRON CNG PHASE-2 ENGINE 32
Engine Timing : Note:- • This Symbol indicates critical tightening torque. SR NO DESCRIPTION NO REUSE SEALANT LUBRICATION TORQUE (KGF.M) 1 Fixed Blade 2 Sprocket Crankshaft 3 Hex Pivot Bolt for Chain Guide (Movable) 2.5 4 Chain 5 Exhaust Camshaft Sprocket To Camshaft, bolt M12x1.25 • 9 ± 5 % 6 Hex FL Bolt M6x25 (2 Qty) 1.0 7 Cam Guide Valve 8 Hex Bolt (Intake Camshaft VVT• ˚ 6 ± 0.5 9 Controller Assy, Valve Timing 10 Exhaust Variable Cam Timing 11 Tensioner Guide Rail 12 H/FL Screw M6 x14 (2 Qty) 1.0 13 Hex FL SCR M6X30 (2 Qty) 1.0 14 Tensioner 1.2L REVOTRON CNG PHASE-2 ENGINE 33
J. EXHAUST MANIFOLD SR NO DESCRIPTION NO REUSE SEALANT LUBRICATION TORQUE (KGF.M) 1 Gasket (Exhaust Manifold) 2 H/FL Bolt M6 for heat shield (3 Qty) 1.5 3 Heat Shield 4 M8X1.25 Flange P/T Nut. (4 Qty) 2.0+0.3 5 Lambda Sensor 5.0±0.5 6 Exhaust Manifold 7 H/FL Screw M8X18 (2 Qty) 2.5 8 Stud C M8X25 for Exhaust (4 Qty) 2.5 1.2L REVOTRON CNG PHASE-2 ENGINE 34
K. CNG FUEL INJECTION EQUIPMENT SR NO DESCRIPTION NO REUSE SEALANT LUBRICATION TORQUE (KGF.M) 1 H/FL SCREW M8X18 (2 Qty) 2 + 0.3 2 HEX FLANGE SCREW M6X14 2 + 0.3 3 BRACKET ASSY, FUEL RAIL (FOR GAS RAIL - CNG) 4 FUEL RAIL 5 CLIP,FUEL INJECTOR (FOR GAS RAIL - CNG) 6 HEX FL SCR M5X10 2.9 + 0.3 7 FUEL INJECTOR (CNG) 1.2L REVOTRON CNG PHASE-2 ENGINE 35
L. FUEL INJECTION EQUIPMENT SR NO DESCRIPTION NO REUSE SEALANT LUBRICATION TORQUE (KGF.M) 1 Hex FL Bolt M8X30 (Common Rail) (2 Qty) 2 + 0.3 2 Assembly Fuel Rail 3 Fuel Injector Clip 4 Fuel Injector 2.9 + 0.3 1.2L REVOTRON CNG PHASE-2 ENGINE 36
M. LUBRICATION PUMP AND COMPONENTS 1.2L REVOTRON CNG PHASE-2 ENGINE 37
Lubrication Pump and Lines : SR NO DESCRIPTION NO REUSE SEALANT LUBRICATION TORQUE (KGF.M) 1 Oil Pump Assy Complete 2 Hex FL Bolt M8X55 for Oil Pump Assy (6 Qty) 2.5 3 Hex FL Bolt M8X30 (2 Qty) 4 Oil Seal (Crankshaft) (Front) 5 Oil Pump 6 Hex FL Bolt M6X28 (13 Qty) 1.0 7 Flanged Clinch Nut M6 (2 Qty) 1 + 0.2 8 Strainer Assembly (For Oil Pump) 9 Gasket (For Filter) 10 HEX FL BOLT M8X22 (For Filter) (3 Qty) 2.5 11 Adaptor (For Oil Filter Mounting) 12 Oil Filter Assembly ¾ th Turn 13 Oil Pressure Switch 3 1.2L REVOTRON CNG PHASE-2 ENGINE 38
N. AIR INTAKE SYSTEM 1.2L REVOTRON CNG PHASE-2 ENGINE 39
Air Intake System : SR NO DESCRIPTION NO REUSE SEALANT LUBRICATION TORQUE (KGF.M) 1 Air Filter Housing Assembly 2 Clamp (75mm Dia) 0.5 3 Clamp (60mm Dia) 0.5 4 Hose, Air Filter To Throttle body 5 Filter Element 6 Scoop, Air Inatke 7 Hex Flange Screw M6X10 2 8 Spr. BD Clamp 9 Reinforcement ,Battery Tray 10 Grommet, Air Filter 11 Hose, Blowby 1.2L REVOTRON CNG PHASE-2 ENGINE 40
O. SPECIAL INSTALLATION 1.2L REVOTRON CNG PHASE-2 ENGINE 41
SR NO DESCRIPTION NO REUSE SEALANT LUBRICATION TORQUE (KGF.M) 1 Belt 2 Hex FL Bolt M8X30 for Tensioner (Qty 2) 3 3 Belt Tensioner 4 Bracket for Compressor Mounting 5 Hex FL Bolt M8X28 (Bracket to block) (Qty 4) 3.5 6 Compressor 7 H/FL Bolt M8X80 for Compressor (Qty 3) 2.2+0.2 8 Hex. FL Bolt M8X100 for Water Pump (Qty 4) 2.5 9 Water Pump 10 Gasket For Water Pump 11 Hex FL SCR M6X18 to Thermostat 1.0 12 Bright Washer 13 Thermostat Housing 14 Alternator 15 Alternator Cover Fitment Bracket: 16 Alternator Guard 17 Hex FL Nut AM6 for Guard (Qty 2) 1.0 18 Hex. FL Bolt M8X80 for alternator (Qty 3) 3.5 19 Water Temperature Sensor 1.8-2.5 1.2L REVOTRON CNG PHASE-2 ENGINE 42
Special Installation : SR NO DESCRIPTION NO REUSE SEALANT LUBRICATION TORQUE (KGF.M) 20 Hex. FL Bolt M8X40 for Starter Motor (Qty 2) 2.4 21 Starter Motor 1.2L REVOTRON CNG PHASE-2 ENGINE 43
P. ENGINE SUSPENSION 1.2L REVOTRON CNG PHASE-2 ENGINE 44
Tightening Sequence Step 1- A Mount - Bolt - Callout No 7 and 8 Step 5- B Mount - Nut - Callout No 3 Step 2- B Mount - Bolt - Callout No 2 and 5 Step 6- C Mount - Bolt - Callout No 10 Step 3- A Mount - Nut - Callout No 6 Step 7- C Mount - Bolt - Callout No 11 Step 4- A Mount Step Torque - Fastener Callout No 14 Step 8- C Mount - Bolt - Callout No 13 SR NO DESCRIPTION NO REUSE SEALANT LUBRICATION TORQUE (KGF.M) 1 B-Mount 2 H/FL Scr M10x30 6.1-6.6 3 Hex. Flange Nut M12x1.25 (Qty.2) 50% PreTorque 5.5 4 Washer (Qty.2) 5 H/FL Scr M10x30 (Qty.2) 6.1-6.6 6 Hex FL Nut M10 (Qty.2) 50% PreTorque 3.3 7 H/FL Scr M10x30 (Qty.2) 6.1-6.6 8 H/FL Scr M10x30 (Qty.2) 6.1-6.6 9 A-Mount 10 H/FL Scr M10x45 (Qty.3) 6.1-6.6 11 Hex Flange Bolt 10.7-11.2 12 C-Mount 13 Hex Flange Bolt 10.7-11.2 14 H/FL BOLT M12X60 50% PreTorque 3.3 15 Bracket, C-Mount 16 Bracket, B-Mount 17 H/FL Scr M10x40 (Qty.5) 4.1-4.6 1.2L REVOTRON CNG PHASE-2 ENGINE 45
Q. CNG SYSTEM SL NO DESCRIPTION NO REUSE SEALAN T LUBRICATION TORQUE (KGF.M) 1 CYLINDER (CNG) 2 2-WAY VALVE ASSY 26.5-30.5 3 HEX FL NUT AM10 -8.8 1.5-2.0 4 CLAMP STRAP LONGER 5 HEX SCR M10x65-8.8 2.5-3 6 BRACKET (REGULATOR CNG) 7 H/FL SCREW M8X14-8.8 2.3 8 HEX FL NUT AM8 - 8.8 2.3 9 WELD STUD M8 X 20 2.3 10 REGULATOR 11 HEX FL SCR M8X14 - 8.8 2.3 1.2L REVOTRON CNG PHASE-2 ENGINE 46
SL NO DESCRIPTION NO REUSE SEALAN T LUBRICATION TORQUE (KGF.M) 12 LP Filter 13 RUBBER HOSE (FILTER OUT TO RAIL) 14 CLAMP STEPLESS EAR 15 HEX FL SCR M6X12 - 8.8 1.5±0.2 16 HOSE (HEATER OUT) 17 HOSE (HEATER INLET) 18 RUBBER HOSE (HPR OUT TO FILTER INLET) 19 H/FL SCREW M8X14 - 8.8 2.3 20 BEND TUBE, CRADLE 21 HEX FL SCREW M10X25 - 10.9 4-4.5 22 HP PIPE (CYLINDER VALVE TO CYLINDER VALVE) 23 CLAMP STRAP SHORTER 24 HEX FL NUT AM10 -8.8 1.5 - 2 25 HEX WELD NUT M6 26 SPACER (FOR RECEPTACLE MTG) 27 H/FL SCR M6X12 0.8-1.0 28 RECEPTACLE 3.5-4.0 29 CAP ASSY,RECEPTACLE 1.2L REVOTRON CNG PHASE-2 ENGINE 47
4. ENGINE TESTS AND MAINTENANCE A. PRELIMINARY INSPECTION GENERAL 1. Check for leakage of Oil, fuel, and Coolant. 2. Check for overheating of engine. 3. Check for unusual smoke. 4. If there is any fault in the Engine Management system (EMS) then the MIL indicator in the instrument cluster will come ON. In such a case connect the diagnostic tester. (For procedure refer EMS section). Before proceeding to carry out actual reconditioning of engine, it is desirable to have a preliminary inspection of engine to ascertain whether an engine reconditioning is necessary and if so, to what extent. Most common reasons for which engine is reconditioned are 1. Loss of power. 2. Excessive engine oil consumption. 3. Extremely low engine oil pressure. 4. Mechanical failures. To know exact reason and general condition of engine, proceed as follows LOSS OF POWER : • Loss of engine power may be due to 1. EMS is in limp-home mode due to some critical fault. 2. Clogged air filter / exhaust passage / catalytic converter. 3. Defective fuel system 4. Clutch slippage 5. Brake binding EMS is in limp-home mode : • If the EMS detects some major fault in the system it switches to limp-home mode, where it runs at a reduced torque. Connect the diagnostic tester and check if any faults are present in the Engine EMS, if found rectify them. (For details refer Engine Management Section) Clogged Air filter / Loss of Charge Air • Pressure/ Choked Exhaust Silencer / catalytic converter : Loss of power with unusual black smoke from engine exhaust indicates lack of air or low air charging pressure to engine cylinders. Clean air filter & inter cooler fins. Check all joints for air leakage. If power loss with black smoke is still felt, check exhaust silencer for choking. Clean and replace silencer if necessary. Check for kink formation in exhaust piping. Defective Fuel System : • Check the Fuel system for fuel flow. If the flow is restricted change the filter. Clutch Slippage : • Clutch slipping can be confirmed by any of the following two methods: Method 1 : 1. Drive the car in 1st or 2nd gear at a minimum speed corresponding to that gear. 2. With the accelerator pedal in a fully pressed position, gradually apply brake with left foot. 3. If the engine stalls, the clutch does not slip. Method 2 : 1. Drive the gear with weight equal to GVW in 3rd gear on a level ground. 2. Allow the speed to drop upto 15kmph. 3. Now press the accelerator pedal fully. 4. With slipping clutch the car will not pick up speed, also a clutch burning smell could be noticed. 5. If this does not occur, the clutch does not slip. Brake Binding : • During driving apply brakes number of times and then shift gear to neutral position and check free rolling of vehicle. Check brake drums/brake discs for overheating and if necessary jack up the vehicle and check wheels for free rotation. NOTE It is always advisable to first use the diagnostic tool and rectify the electrical faults, before commencing with mechanical repairs/ troubleshooting. Refer ENGINE MANAGEMENT SYSTEM section in this group for procedure. 1.2L REVOTRON CNG PHASE-2 ENGINE 48
B. ENGINE TESTS ENGINE COMPRESSION TEST I. Description : • The engine compression test provides the technician with information regarding the condition of the engine piston rings/block, cylinder head gasket, and the valves. Before performing the engine compression test, make certain the loss of power or overheating cannot be attributed to something simple such as improper fuel, obstructed air filter, low oil or coolant level, or dragging brakes. Test Procedure : • 1. If possible, bring the engine up to operating temperature (approximately 80° - 90° C) by starting and driving the vehicle for several minutes. 2. Make sure the vehicle battery is fully charged. 3. Remove the air filter element. 4. Label the spark plug coils and remove all spark plugs from the engine. 5. Install an engine compression test gauge (0 to 25 bar) into the number one engine cylinder spark plug port. . (Remove fuel injector connections to avoid fuel injection). 6. Depress the clutch and accelerator pedal fully and crank the engine 7. Have an assistant read and record the highest pressure obtained on the gauge. 8. Follow steps 5 through 7 for the three remaining cylinders, recording the pressure obtained on the gauge. 9. Compare the compression reading obtained for each engine cylinder. The minimum compression is 12±1 bar. If the compression reading in a cylinder is 10. below 10 bar, there may be leakage past the piston rings or valves. Squirt a several drops of oil into the cylinder bore and perform the compression test again. If the compression improves after several 11. drops of oil are squirted into the cylinder bore, the piston rings are most likely leaking. If the compression does not improve, the valves may be allowing leakage. If the compression between two adjacent 12. cylinders is below the minimum, there may be a leak in the head gasket between the cylinders. If suspecting a blown head gasket check the engine oil and coolant for signs of contamination. If coolant mixes with the oil in the sump, the oil will appear to be a dark, milky, substance. If cylinder compression is leaking into the coolant, bubbles will appear in the coolant reservoir while the engine is running. CAUTION Use care not to damage the threads in the spark plug port when installing the compression test gauge adapter. 1.2L REVOTRON CNG PHASE-2 ENGINE 49
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