Valve Train Analysis - Dynamic
ROCKER ARM- Check for plugged oil in rocker arms or cylinder head.
- Check for proper overhead valve train lubrication
If insufficient oiling is suspected, accelerate the engine to 1200 rpm-100 rpm with the transmission in NEUTRAL and the engine at normal operating temperature. Oil should spurt from the rocker arm oil holes such that valve tips and rocker arms are well oiled and/or, with the valve covers off, oil splash may overshoot rocker arms. If oiling is insufficient for this to occur, check oil passages for blockage.
VALVES AND CYLINDER HEAD
- Check for plugged oil drain back holes.
- Check for missing or damaged valve stem seals or guide mounted valve stem seals.
- Check for plugged oil metering orifice in cylinder head oil reservoir.
If insufficient oiling is suspected, check oil passages for blockage, then accelerate the engine to 1200 rpm with the transmission in NEUTRAL and the engine at normal operating temperature. Oil should spurt from the rocker arm oil holes such that valve tips and camshaft roller followers are well oiled. With the valve covers off, some oil splash may overshoot camshaft roller followers.
CAMSHAFT LOBE LIFT
Check the lift of each camshaft lobe in consecutive order and make a note of the readings.
1. Remove valve covers.
2. Remove spark plugs.
3. Install Dial Indicator With Bracketry so that the rounded tip of indicator is on top of camshaft lobe and on the same plane as valve tappet.
4. Rotate crankshaft until base circle of camshaft lobe is reached.
5. Zero the dial indicator. Continue to rotate crankshaft until (A) high-lift point of camshaft lobe is in fully-raised position (highest indicator reading).
6. To check accuracy of original indicator reading, continue to rotate crankshaft until (B) base circle is reached. The indicator reading should be zero. If zero reading is not obtained, repeat Steps 1 through 6.
NOTE: If lift on any lobe is below specified service limits, the camshaft roller followers operating on that camshaft must be replaced.
7. Compare total lift recorded on dial indicator with specifications.
8. Remove Dial Indicator With Bracketry.
9 Install spark plugs.
10. Install valve covers.