ENGINE. 61 7. Check for leakages through valve seat by pouring gasoline on valve head. Gasoline must not seep past valve seat. E VALVE SEAT INSERTS: 1. For removing valve seat inserts from cylinder head use suitable boring machine. Bore old insert thin (About 0.5 mm thickness) and then pry it out. 2. Alternatively use a suitable turning tool to cut an annular groove into valve seat insert and then pull it out with a suitable puller. In order to avoid damaging machined cylinder head mating surface with crank case, place any soft protective sheet metal under supports of puller. 3. Measure valve seat insert bore diameter in cylinder head. 4. If boring and prying is done carefully without damaging valve seat insert bore in cylinder head, fitment of an over size valve seat insert will not be necessary. 5. Re-machined valve seat insert bore in cylinder head must be exactly at right angle to cylinder head mating surface with crank case. 6. All specified dimensions should be strictly maintained to ensure proper interference of valve seat insert in its bore. 7. Clean valve seat insert and its bore in cylinder head thoroughly. F JUST BEFORE INSTALLATION: 1. Place valve seat insert in mixture of Methanol and dry ice for about 20-30 minutes to bring temperature down to -150ºC. 2. Heat cylinder head to approximately 80ºC in hot water bath. 3. Install valve seat insert in cylinder head bore quickly by light hammering 4. Machine valve seat in cylinder head. G CAM SHAFT INSPECTION 1. Check cam shaft run out at 2nd journal by supporting it on V-block at 1st and 3rd journal. 2. Check cam shaft journal dimensions. Record the readings. 3. Carry out visual inspection of cam shaft for: • Overheating of journals, this is indicated by bluish/ brown colour. • Deep scoring marks on journals and cam lobes • Cracks, which should be checked on a magnetic crack detector. 4. Check hardness of cam shaft journals and cam lobes, it should be 47 HRC.
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