Recently my oil pressure gauge stopped displaying any oil pressure reading on my 86 EA82 GL Wagon. I disconnected the wire that goes from the oil pressure sending unit to the gauge and grounded it to ensure it would peg the oil pressure gauge. The gauge did go all of the way up with that wire grounded, so I assumed the oil sending unit was bad. I replaced the oil pressure sending unit but still I have no oil pressure reading. I made sure to get the oil pressure sending unit for a gauge and not for a dummy light. I know the oil pressure sending unit is working considering my valves aren't clacking. Any ideas of what to try next?

I would make sure that you're getting good contact between the wire and

the sending unit.

And I would check the wire for any breaks in the insulation.

It could be shorting before it gets to the guage.

 

Twitch

I had a similar problem with my Brat, turns out the guy at NAPA gave me a sender for a car with a warning light. They open with pressure, instead of decreasing resistance with increasing pressure.

I have verified the wiring is good all of the way up to the oil pressure sending unit. I can unplug the wire from the oil pressure sending unit and ground it out to verify the gauge really is working and that there is no wiring issues. I also called NAPA and had them verify it was the correct part. It definitely is the correct part, so I went ahead and returned the part anyway and got a new one just in case the oil pressure sending unit I had just bought was defective. With the new oil pressure sending unit I am still not getting an oil pressure reading. I can tell I actually have oil pressure since my lifters and valves aren't clacking. I also verified that oil is making it to the pressure sending unit by starting the car with the oil pressure sending unit off of the car. Of course oil shot out of there, so I know oil is making it to the oil pressure sending unit. Any ideas? What am I missing? Is it possible that I am actually not getting enough oil pressure for a reading on my gauge? Wouldn't I hear some awful loud clacking if I really didn't have good oil pressure?

 

Thanks!

~Bobby

Well I just did the same thing. Except I watched my pressure go sky high on a -3 F morning, and then to nothing displayed. I thought it was my sending unit, so I replaced it. It is still reading very low, no where near what it used to be. After reading this bbs, I decided that it was probably the o rings in my oil pump. I had about 215,000 on my 1.8 spfi, and that seems to be about right for the seals to fail. Maybe you should look into that too. :-\

 

I have used the car since, the lifters aren't clacking - but all the same, I'll be pulling the engine out for other things anyway.

 

$.02

Had the same problem with the 87" wag that I put an EA81 in, Put a manual gauge on it and had good pressure. The gauge in the dash was bad, it even peg when I grounded it and was dropping below the zero mark.

Unk

So even if the gauge pegs when you ground it, it still can be bad? Now I wonder if the problem is the oil pump, the oil pump gasket/o-rings, or maybe just the gauge itself. My EA82 has 186k on the odometer and the oil pump appears to be stock. Both heads have been rebuilt recently, but the bottom end is likely original. Maybe it's time to either pickup an after market oil pressure gauge or replace the oil pump and o-rings.

Can't I use a multi-meter to determine if the oil sending unit is generating any output that the oil pressure gauge should be reading? If there is no output from the oil pressure sending unit then I'd know the gauge is likely just fine and that it's something more than likely to do with my oil pump at that point. Does anyone know what kind of output I should be seeing from my multimeter when I test the oil sending unit?

 

Thanks again for the input everyone!

 

~Bobby