53 4 DLT ENGINE VALVE SEAT INSERTS For removing valve seat inserts from cylinder head use suitable boringmachine.Bore old insert thin (about 0.5 mm thickness) and then pry it out. 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. Measure valve seat insert bore in cylinder head. 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. Re-machined valve seat insert bore in cylinder head must be exactly at right angle to cylinder head mating surface with crank case. All specified dimensions should be strictly maintained to ensure proper interference of valve seat insert in its bore. Clean valve seat insert and seat insert and its bore in cylinder head thoroughly. Just before installation. - Place valve seat insert in a mixture of Methenol and dry ice for about 20-30minutes to bring its temperature down. – Heat cylinder head to approximately 800C in water bath. Install valve seat insert in cylinder head bore quickly by slight hammering. - Refer figures 90 & 91 Machine valve seat in cylinder head. CRANKSHAFT Clean and carry out visual inspection of crank shaft for following. Over heating of journals, which is indicated by bluish brown colour. Scoring marks on journals. Cracks, which should be checked on magnetic crack detector. Check hardness of journals. Check crank shaft run out by supporting it on V-block at 1st and 5th main bearing journals - Refer Figure 92. Fig. 90 Fig. 91 Fig. 92
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