divil

My car has had the oil-pressure-gauge-pegged-high problem since I got it - it would go to around 1 at "key on", and then about 1 second after start up it would peg above 5 and never move from there.

I did some checking with an ohmmeter - one terminal of the sender is grounded with almost no resistance, the other has about 890 ohms between it and ground (cold idle). From reading on Clark's Garage, 184 ohms equates to 5 bars on the gauge. I take this to mean I should never be seeing anything like 890 ohms if the unit is working correctly? On the other hand, he says nothing about what the other wire should show, and I can't tell which wire is which.

Anything else I can do before I replace the sender?

PS. I tried swapping the wires...that resulted in some new warning lights at key on that I never saw before but the gauge now pegs at 5+ all the time, even before I start the engine.

Van

Senders die all the time. Just buy a new one.

divil

ok...I thought I'd probably have to do it anyway. I did notice one more thing...don't know how much this matters but I read in another thread that if the oil pressure warning bulb is dead, the gauge will peg high...

Well I just noticed that my oil pressure warning light doesn't come on with all the other lights when I turn the key - so I might try replacing that bulb first just in case, since I presume I need it anyway.

Butters944

Try the bulb then the sender

Van

First off, it's harder to pull the dash (at least on an '85.5+) than replace the sender...

Second, I don't believe that the bulb and gauge are related - because the sender has two terminals on it - one for the bulb and one for the gauge. They should operate independently... And if both are not working... than, dollars to donuts, it a bad sender.

John_AZ

I had an old oil pressure sender and wanted to know why it went bad...

Gunk gets inside or the potentiometer (?) is corroded.





I needed one locally at the last minute and it cost me $$$.

Shop for best price.

John

divil

Haha yeah I read up on the procedure after posting that and I think maybe I'll just replace the sender to start with

StoogeMoe

So that's what's inside of those things. How primitive. It's a wonder they even last at all.

gtroth

Turn the key to the position just before start and see if the ! light works.

divil

No actually it doesn't. I can't remember if that worked before I switched the wires.

After checking the manual, I have 3 lights that should come on at key on, but don't: The ! light, the oil warning light, and the alternator light.

sweetskillsrk

What does yall's oil pressure gauge on the dash normally read? Mine has, since I've owned the car (4+ years), consistently stays at the 5 line and occasionally drops a little lower than that. What's normal? I'm getting ready to replace the head gasket so if it's the oil sender is bad I might as well replace it while it will be really easy to get to.

divil

This

A bit more info here

Usually they seem peg high (way above 5) when they fail but from searching the archives I've heard of a few that behave differently.

sweetskillsrk

I should've known to check Clark's first, sorry about that. However, in light of what I read I'm pretty sure mine is bad, though I'll run the tests to be sure. I'll be ordering a few parts from Pelican and they have both the VDO $120 sender and also the FAE (knockoff) $30 one. Which would you suggest? I know the VDO is probably going to be a little higher quality but is it really worth the extra $100? If it is I'll pay it, just don't feel like spending the extra money if I don't have to. I'd also be willing to buy a good one off of someone is anyone has one laying around, even if it's used.

divil

Well I just replaced my sender and it's working nicely now. I had tested the gauge as per Clark's Garage so I knew that was ok.

But I still don't have my oil pressure warning light at key-on, or my central warning light and alternator light. Maybe those bulbs are just blown.

John_AZ

3rd time to post this picture, and make the point.
Rennlist sponsor 944Online.

Use the FAE, I would not buy a used OEM--it could be 25 years old and faulty.
Even if the ebay seller swears it came from a "good running car".



GL
John