VCCA Home Forums TECHNICAL - 1945 AND EARLIER 1937-1945 Oil gauge not working

I had a shop take out and reinstall the dash on my 40 chevy (after woodgraining), and now the oil gauge does not register. I haven't found any information in the shop manual (or in these forums) about how it works or how to fix it so I'd appreciate any tips for things to check. (Yes I could take it back, but I'd rather fix it myself and learn something if possible.)

I'd like to see pics of the dash!

Was the oil line perhaps plugged while it was out to prevent leakage? Might be some still in there. Or, have you checked to make sure they reconnected the oil line? Simple stuff first, eh?

There is a small line from the engine to the gauge so you want to check to make sure the line is not kinked and shouting off oil flow to the gauge. Also make sure the line is hooked to the engine.

I'm working on posting pictures of the dash in the Member's Photo area!

The line is hooked to the oil gauge and engine.

Thanks for asking! I uploaded a picture of the reinstalled dash and trim into the Member's gallery:

Dash/trim picture

Can't go there. Can you post it here?

Disconnect the oil line to the back of the oil pressure gauge. Place a rag over the end of the line and start the engine so you can check if any oil exits the oil line.

Ray,

Not intending to nit-pick your excellent suggestion but wouldn't it be easier to first check to see if there is oil pressure coming out of the block by taking the line loose there first?

I don't know about you but for me being upside down under the dash is tantamount to having to kiss my sister when forces to make-up after a childhood fight. You know.

Just wondering,
Charlie

It is not necessary to disconnect the oil line. With engine running just loosen the line a half turn or so. If there is any flow it will begin to slowly drip. I would start on the engine end of the line first. Then go to the gauge if you verify flow at the engine.

If the oil drained out of the tube while it was disconnected, it may need to be bled to get oil up to the gauge.

Actually in many cases you don't want oil in the gauge or entire line to the gauge, just air. The air cushion takes out most of the pulsating of the oil pressure that is produced by some pumps. The air will also flow where oil will not. The gauge does not care what the medium is as long as it can flow back and forth.

Thanks so much for the instructions - I now have a working oil gauge!

Two of the problems I found after getting the car back from the shop were that the oil gauge didn't work and that the rear view mirror arm was missing. I didn't realize those two problems were connected until I checked the oil line fitting at the gauge. It turns out that the rear view arm fits into the oil gauge and the oil line fits the other side! Now that the rear view arm is in its proper place, the oil gauge works too! Thanks for the help though - I learned a bit more about the car this week!

And here is the re-woodgrained dash:

huh?

In hindsight, I should have removed the dash/moldings myself rather than having an upholstery shop do it. They didn't label the parts, so when re-installing everything after the woodgrain work was done, they apparently just screwed the rear view mirror arm into the first place it fit (the oil gauge)!

Joe, I am having a hard time trying to imagine the rear view mirror arm being screwed in the oil gauge (hole?). Was he trying to plug up the oil passage with any thing he could find?

Do you have a dash mounted mirror? I can't imagine the oil line being anywhere near the top of the windshield..

Don't ask me! It was just this part so it didn't look that odd until I figured out where it was supposed to go:

It may well be the part shown was used as temporary "plug" that didnt get changed back and happens to come off the mirror mounting.
Tony