Time to play another round of “What’s Wrong With My Car?!”

MyLittlePony · Oct 10, 2024

So, I’ve had this car forever. I know that the factory oil gauge is really just an on/off switch. One time, it was low on oil, and the gauge dipped a little. I don’t remember which letter is fell on, but I only noticed it because the battery gauge dipped too. Both “normal” but on different letters that weren’t typical for it to be. Added a quart, problem fixed. I think later I discovered that both gauges shared some connection, so the oil was probably drawing power away from the battery gauge.

Flash forward to almost 20 years later, and it happens again, only this time, it’s pegging high. I check the dip stick, dry. I add a full quart of oil, and the dip stick shows full, so I drive off. Car pegs high oil pressure, and starts over heating. I have aftermarket gauges though, and oil pressure looks fine, but the temperature gauge is climbing to the point where it also pegs, and I have to pull over.

I burp the car. It needed it. Added whatever coolant it thinks it needed, and decide to drive it like normal. Car goes back and fourth between having high oil pressure/low(ish) battery/and overheating, and having normal oil pressure/normal battery/and normal temperature. Back and fourth from panic mode to alls good. Meanwhile, aftermarket gauge shows good oil pressure when factory shows high. HOWEVER aftermarket temperature climbs just as the factory temperature climbs UNTIL factory oil pressure gauge goes back to normal.

So I’m thinking maybe the factory oil pressure sender switch is wonky, and decide to change it out. Did that today. Turn the car on, and the factory gauge pegs high again. So that’s not it. I can’t drive the car if it’s going to overheat, and the amazing LMR cruise in is next month, not to mention that it’s finally cool enough to have the top down. Is there some connection to the computer that tells the engine to work harder if the oil gauge reads high? Could there be a wiring issue that I could be directed to looking at? Could there be a bad oil pump that sometimes works and sometimes doesn’t, that causes the randomness of the oil pressure? The one thing that doesn’t change is the fact that it never reads low, either normal or high.

RAU03MACH · Oct 11, 2024

first make sure the oil sender is working properly
make sure timing is correct
the overheating check make sure it is system is working good
did you ever run the compression test

RAU03MACH · Oct 11, 2024

i would also check the wire harness to make sure its not grounding out somewhere
no cuts or fray wires
also check make sure the oil sensor is in good shape
there may be multiple things going on
you would need to eliminate one by one

96blak54 · Oct 11, 2024

I had an '87 Bronco II that did this. I loved that that thing! I did so much youth with it! And now im sad that I sold it off.
Anyhow, its oil psi gauge, water temp, and battery gauge would randomly peg out. I remember the 1st time it did that on me. It freaked me out, heart racing, cars gonna blow up scared, but just as it did it and as I was watching, the gauges softly returned to the running position. Confused, I just kept driving. Shortly after, maybe a week or two, it does it again. And then it became a normal thing that I accepted. I never tried to fix it or even look into it. My best guess was a cluster issue. Possibly shorting out.

I hope you figure yours out. Good luck

MyLittlePony · Oct 11, 2024

96blak54 said:
My best guess was a cluster issue. Possibly shorting out.

I thought about swapping out the instrument cluster, to rule that out, but it doesn’t explain the overheating aftermarket gauge. Like you, I originally figured I’d just live with it, since the oil pressure was normal in the aftermarket gauge, but when I discovered a link between the factory gauges, and the aftermarket temp, I figured I can’t ignore it.

Daryl · Oct 11, 2024

Oil sending unit, like rau said. PITA to get to but critical component

MyLittlePony · Oct 11, 2024

RAU03MACH said:
i would also check the wire harness to make sure its not grounding out somewhere

I showed my husband this thread. He walks out to the garage, holds up a loose cable, asks me where it goes, then tells me to screw it on the firewall. There was a grounding wire attached to the back of the engine with a ring terminal on the other side attached to nothing. I had mentioned my previous history with the issue, but did not remember the solution. This is what happened apparently almost twenty years ago, only instead of finding the lack of a grounding cable, he pulled the engine to replace a performance oil pump with a standard one first.

Anyway, since my bizarre set up required me to disconnect a coolant hose, I ended up adding coolant and burping the car. While it did all that idling, it didn’t peg out at all. Before that, parked at idle, it would bounce around. I guess my car shakes a bit. I have been without my car for a few weeks, when that’s all I had to do. I wonder what a test drive will be like with the AC on.

Daryl · Oct 11, 2024

MyLittlePony said:
I showed my husband this thread. He walks out to the garage, holds up a loose cable, asks me where it goes, then tells me to screw it on the firewall. There was a grounding wire attached to the back of the engine with a ring terminal on the other side attached to nothing. I had mentioned my previous history with the issue, but did not remember the solution. This is what happened apparently almost twenty years ago, only instead of finding the lack of a grounding cable, he pulled the engine to replace a performance oil pump with a standard one first.

Anyway, since my bizarre set up required me to disconnect a coolant hose, I ended up adding coolant and burping the car. While it did all that idling, it didn’t peg out at all. Before that, parked at idle, it would bounce around. I guess my car shakes a bit. I have been without my car for a few weeks, when that’s all I had to do. I wonder what a test drive will be like with the AC on.

Interesting. Keep us posted!!