H Y D R A U L I C T A P P E T S
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DET
AILED MAINTENANCE PR
OCEDURES
Tappets are self-adjusting and hydraulic. These type of tappets automatically adjust to keep the valve
mechanism free of lash while the motor is running to reduce valve wear. The valve mechanism may be slightly
noisy when the motor is cold, until the hydraulic tappets “pump-up” or completely repressurize with oil. If at any
other point the valve mechanism becomes excessively or abnormally noisy, it may indicate that one or several of
the hydraulic units are not functioning correctly. Always check oil supply first, as normal oil circulation through the
engine is necessary for hydraulic units to function properly. If there is oil in the tank, there may be dirt or debris in
the oil supply passages leading to the hydraulic units, thereby causing the units to function improperly. Inspect
and clean tappet oil supply filter screen.
AmIronOwnerManual_body_06.qxp 5/22/2006 9:23 AM Page 66
