Type_LT

Hi guys,

Sometimes when I start my 86 951 the oil gauge stays pegged at 0. The car is on level ground and the oil is halfway between the marks on the dipstick. I'm using an OEM oil filter, the one with the valve to prevent the oil from draining from the filter. I'm not too familiar with the oil pump system but I'm assuming there is a valve that is sticking or something. This only seems to happen maybe once or twice a month. Something is either preventing oil to the oil pump or the pump itself is having trouble. After the oil finally grabs the gauge will peg out to 5 like it should when cold. After warm the gauge moves down to 2-3 at idle and about 4.5 on the interstate, normal operation there. Is there some valve or something sticking?

Toolmaster

Hey there.

I'd try an oil change, with a new filter. That should correct the issue.

HTH!

nib5

Sounds like the behaviour my car exhibited when the oil pressure relief valve stuck. It's screwed into the block under the oil filter. I took mine out, cleaned it and put it back in. It has worked fine after that up until now. Someone with greater knowledge of the 951 engine may be able to offer more.

Toolmaster

Nib -

True -- that's a possibility too, but I'd usually expect that the valve sticking would result in more of a regular oil pressure problem.

And at about 200ish bucks + to replace, I like to start with the cheaper potential fixes.

Thanks!

kennyandersen

I would also look at the oil pressure relief valve -- that's what it sounds like to me as well. Since all (virtually all anyway) oil filters have built-in bypass valves I would be skeptical of this as your problem (maybe not immpossible but very unlikely)

nib5

Obviously, I would have to second the oil & filter change suggestion, as it is cheap, can't do any harm and might just do the trick. I would also take a look at the electrical connections to the pressure sender (also under the filter). Doubtful, but cheaper still. DO NOT over tighten the wires to the studs though, they are hollow and will break off - don't ask

Type_LT

I did an oil change less than two weeks ago with the mahale filter. Maybe thats not your point though, is it that I got unlucky and got a bad filter? I'm pretty sure the gauge wiring is fine as the oil gauge works perfectly when there is actual oil pressure going to the engine.

johnjcoyle

Hi,

It does sound like to relief valve to me.

If you want a good as new used valve let me know.

As previously mentioned a new one is big$$$ I am sure we can come to a cheap conclusion if you need it.

Good luck with it.

TheJonesBoy

Sounds like an intermitten electrical problem to me. I would check the gauge and sending unit. Run the wire for the sending unit into the car, and keep a voltmeter handy. Just switch it on and see if you get a reading when the gauge is at 0. I have just started to get problems with "sleepy" needles on my gas gauge and speedo.

Never trust anything electromechanical, espically when liquids are involved.

scular

I am surprised no one asked this sooner, but does it make any metal to metal sounds, when there is no pressure?

Obviously, if there is no noise then more than likely it is some electrical problem, but if it makes evil sounds, check out the relief valve, mine needed an oring on the end.

Manning

Darn, that was going to be my question!

So to summarize, when you start the car the oil pressure gauge reads 0 for a moment, the engine does or does not sound a little rougher than normal (?), the reading on the gauge pops up to normal and the engine sound (if it had been rough) smooths out?

nib5

I don't know about the sound, my car did not make the tappety noise that comes from low pressure, yet the OP gauge was zeroed. I changed the sender - see previous post - it was still zeroed. When I cleaned the PRV and put it back in the the pressure shot up in a second. Unless I get a signed affidavit from my engine that it has pressure, I would not assume electrical and it stays on the driveway.

Type_LT

Yes I did notice a noise that sounded like a clanking, i'e no oil in oil pump. When I heard it I shut it off pretty quick however, I think i'll start with the relief valve. I check out the manuals later on to see what and where it is.

Thanks

Toolmaster

Type_LT -

I'd also do the oil change. The oil pump keeps it's prime through the center hole in the oil filter. If the filter you put on was faulty, then there's a chance it'll loose it's prime which is your issue.

If a new filter doesn't fix it, then look at the pressure valve.

HTH!