A I R I N L E T A N D E X H A U S T S Y S T E MTM 5-3805-258-24-1T E S T I N G A N D A D J U S T I N GCRANKCASE (CRANKSHAFTCOMPARTMENT) PRESSUREPistons or piston rings that have damage can be thecause of too much pressure in the crankcase. Thiscondition will cause the engine to run rough. Therewill also be more than the normal amount of fumescoming from the crankcase breather. This crank-shaft pressure can also cause the element for thecrankcase breather to have a restriction in a veryshort time. It can also be the cause of oil leakage atgaskets and seals that would not normally haveleakage.Normal crankcase pressure with a clean crankcasebreather is 50.8 mm (2 in.) of water or less.CYLINDER HEADThe cylinder head has valve seat inserts and valveguides that can be removed when they are worn orhave damage. Replacement of these components canbe made with the tools that follow.ValvesValve removal and installation is easier with use of5S1330 Valve Spring Compressor Assembly and5S1322 Valve Keeper Inserter.Valve Seat InsertsTools needed to remove and install valve seat insertsare in the 6V4805 Valve Insert Puller Group. Spe-cial Instruction Form No. SMHS7935 gives an ex-planation for this procedure. The insert can be moreeasily installed by lowering the temperature of the in-Valve GuideTools needed to install valve guides are: 7S8858Driver Bushing and 7S8859 Driver. The counterborein the driver bushing installs the guide to the correctheight. Use a 1P7450 Honing Arrangement to makea finished bore in the valve guide after installing theguide in the head. Special Instruction Form No.SMHS7526 gives an explanation of this procedure.Grind the valves after installing new valve guides.VALVE CLEARANCENOTE: Valve clearance is measured between therocker arm and the valves.VALVE CLEARANCE CHECK: ENGINE STOPPEDExhaust . . . . . . . . . . . . . . . . . . 0.56 to 0.71 mm (.022 to .026 in.)Intake . . . . . . . . . . . . . . . . . . . . 0.30 to 0.46 mm (.012 to .018 in.)NOTE: When the valve lash (clearance) is checked,adjustment is NOT NECESSARY if the measure-ment is in the range given in the chart for VALVECLEARANCE CHECK: ENGINE STOPPED. Ifthe measurement is outside this range, adjustment isnecessary. See the chart for VALVE CLEARANCESETTING: ENGINE STOPPED, and make the set-ting to the nominal (desired) specifications in thischart.V A L V E C L E A R A N C E C H E CK( T Y P I C A L E X A M P L E)V A L V E C L E A R A N C E S E T T I N G : E N G I N E S T O P P E DExhaust . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...0.64 mm (.025 in.)Intake . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 0.38 mm (.015 in.)1. Put No. 1 piston at top center (TC) on thecompression stroke. Make reference to FIND-ING TOP CENTER COMPRESSION POSI-sert before installing it in the head.4-27TION FOR NO. 1 PISTON.
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