Oil Pressure...gauge or pressure relief spring ?

[Vazlov1949]

Hi everybody. If my oil pressure gauge reads 20 with the engine not running and 60 while driving does this mean the gauge is off or does it mean my pressure is too high because of a faulty or stuck pressure relief spring ? I'm running non detergent 30w in a original 94,000 mile 49 pilothouse stock motor. It runs great, does not burn any oil and has probably never been apart for any reason. What do you think> Gauge out of wack or too much pressure?

[TodFitch]

Hi everybody. If my oil pressure gauge reads 20 with the engine not running and 60 while driving does this mean the gauge is off or does it mean my pressure is too high because of a faulty or stuck pressure relief spring ? I'm running non detergent 30w in a original 94,000 mile 49 pilothouse stock motor. It runs great, does not burn any oil and has probably never been apart for any reason. What do you think> Gauge out of wack or too much pressure?

If the dash unit is indicating 20 when the engine is off then there is a problem with the dash unit. There might be other problems too. But definitely the dash unit as an issue.

I'd probably take it out, bend the linkage between the bourdon tube and the needle to get it to read 0 when there is no pressure. Don't bend the bourdon tube. Don't bend the needle. Just the linkage between them.

Then reinstall it and check the pressure reading while the engine is running at a known RPM. Then connect a different pressure gauge and see what it says at the same RPM and engine temperature.

[Vazlov1949]

Thanks for the advice Todd

[grey beard]

I'd first suggest you unhook your dash gauge line at the back of the gauge, and then unhook the line at the block. Now blow compressed air through the line from the dash downward - less messey that way - and see if the line is clear. Then I'd spray a little carb cleaner or brakeclean spray into the back of the gauge and see if things free up that way.

The gauge circuit is a dead-end sort of circuit, and ninety four thousand miles of one-way pressure may very well have seen some dirt or debri work itself into the tube or back of the gauge. If all this fails, someone here on the forum will have an extra gauge. You'll likely need it at that point.

Good Luck

[Vazlov1949]

Thanks for the suggestion.

[Don Coatney]

You should also connect another gauge and see what it is reading.