808264 Mercruiser SCREW

To prevent possible injury, do not use the starter to turn the flywheel. Hot engine components can cause burns. Allow additional time for the engine to cool before measuring valve clearance.
If the valve lash requires adjustment several times in a short period of time, excessive wear exists in a different part of the engine. Repair the problem in order to prevent more damage to the engine.Not enough valve lash can be the cause of rapid wear of the camshaft and valve lifters. Not enough valve lash can indicate that the seats for the valves are worn.Valves become worn due to the following causes:
Incorrect operation of the fuel injection nozzles
Excessive dirt and oil are present on the air filter.
Incorrect fuel settings on the fuel injection pump.
The load capacity of the engine is frequently exceeded.Too much valve lash can cause broken valve stems, valve springs, and valve spring retainers. Too much valve lash can be an indication of the following problems:
Worn camshaft and valve lifters
Worn rocker arms
Bent pushrods
Broken socket on the upper end of a pushrod
Loose adjustment screw for the valve lashIf the camshaft and valve lifters show rapid wear, look for fuel in the engine oil or dirty engine oil as a possible cause.Valve Lash Check
The temperature of the engine does not change the valve lash setting.An adjustment is NOT NECESSARY if the measurement of the valve lash is in the acceptable range. Check the valve lash while the engine is stopped. The clearance is specified in Table 1.
Table 1
Valve Lash
Valves Acceptable Clearance for Valve Lash
Inlet 0.20 mm (0.008 inch)
Exhaust 0.45 mm (0.018 inch) Valve Lash Adjustment
The valve lash is measured between the valve stem and the rocker arm lever. Refer to the Systems Operation, Testing and Adjusting Module, "Valve Lash Check" topic in this Module for the correct valve lash.Note: The No. 1 cylinder is at the front of the engine.
Illustration 1 g00323903
Setting the valve lash
(1) Adjustment screw
(2) Feeler gauge Perform the following procedures in order to adjust the valve lash:
Set the No. 1 piston to the top center position on the compression stroke. Before adjustments are made, lightly tap each rocker arm at the top of the adjustment screw. Use a soft mallet to ensure that the valve lifter seats against the camshaft's base circle.
Measure the valve lash for the inlet valves and the exhaust valve on the No. 1 cylinder. If necessary, adjust the valve lash on the inlet valve and the exhaust valve for the No. 1 cylinder. Note: The 3054B Engines require the use of a TORX T27 driver to adjust valve lash.
Loosen the locknut that is on adjustment screw (1).
Place the appropriate feeler gauge (2) between the rocker arm and the valve stem. Turn adjustment screw (1) while the locknut is being held from turning. Adjust the valve lash until the correct specification is achieved.
After each adjustment, tighten the locknut while valve adjustment screw (1) is being held from turning.
Turn the crankshaft for 180 degrees in the direction of the normal engine rotation. Measure the valve lash of the inlet valve and the exhaust valve of the No. 3 cylinder. If necessary, adjust the inlet valve lash and the exhaust valve lash on the No. 3 cylinder.
Loosen the locknut that is on the adjustment screw (1).
Place the appropriate feeler gauge (2) between the rocker arm and the valve stem. Turn adjustment screw (1) while the locknut is being held from turning. Adjust the valve lash until the correct specification is achieved.
After each adjustment, tighten the locknut while valve adjustment screw (1) is being held from turning.
Turn the crankshaft for 180 degrees in the direction of the normal engine rotation. Measure the valve lash of the inlet valve and the exhaust valve of No. 4 cylinder. If necessary, adjust the valve lash on the No. 4 cylinder.
Loosen the locknut that is on adjustment screw (1).
Place the appropriate feeler gauge (2) between the rocker arm and the valve stem. Turn adjustment screw (1) while the locknut is being held from turning. Adjust the valve lash until the correct specification is achieved.
After each adjustment, tighten the locknut while valve adjustment screw (1) is being held from turning.
Turn the crankshaft for 180 degrees in the direction of the normal engine rotation. Measure the valve lash of the inlet valve and the exhaust valve of No. 2 cylinder. If necessary, adjust the valve lash on the No. 2 cylinder.
Loosen the locknut that is on adjustment screw (1).
Place the appropriate feeler gauge (2) between the rocker arm and the valve stem. Turn adjustment screw (1) while the locknut is being held from turning. Adjust the valve lash until the correct specification is achieved.
After each adjustment, tighten the locknut while valve adjustment screw (1) is being held from turning.