G424 Service Manual Adjustment and Troubleshooting176
Oil Pressure Diagnostics
The following table contains important information for the checking of oil pressure.
Condition Information
1. Measuring oil pressure. Use a good automotive oil pressure test gauge. Do not rely on the oil
pressure gauge in the instrument panel.
2. Check engine oil level. Oil level should be between the "MIN" and "MAX" marks.
3. Oil level in crankcase May cause loss of engine speed, oil pressure gauge
above "MAX" mark. fluctuation, drop in oil pressure and hydraulic valve lifter noise at high RPM.
4. Oil level in crankcase Low oil pressure, oil pressure gauge fluctuation, internal below at or below
"MIN" mark. engine noise and/or damage.
5. Change in oil pressure. This may be a normal condition. Oil pressure may read high in the cooler
times of the day and when engine is not up to operating temperature. As
the air temperature warms up and the engine is running at normal operating
temperature, it is normal for oil pressure to drop off slightly.
6. Low engine oil pressure With modern engines and engine oils, low oil pressure readings at idle or
high rpm do not necessarily mean there is a problem. If valve lifters do not
"clatter" (at idle), there is a sufficient volume of oil to lubricate all internal
moving parts properly. The reason for the drop in oil pressure is that engine
heat causes an expansion of the internal tolerances in the engine and, the
oil will thin out somewhat from heat.
7. Engine-to-engine variance. It is not uncommon to see different oil pressure readings between like
engines, as long as they fall within specifications. Differences in oil
pressure can be attributed to differences in engine tolerances, gauges,
wiring, senders, etc.
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