BeerBurner

A spin-off of POP's earlier thread, but I thought I'd make a separate one since it seems my symptoms are a bit different...

Hola!

Recently, I noticed that my 944's oil pressure would peg itself at the top of the gauge (5 bar). At first, I figured it was just the sender had died. But I also noticed as the car warmed up, the pressure would be at about 4 bar at idle, then maxing out when the engine was rev'd.

While testing to see if the oil pressure idiot light worked (as suggested in the other thread... at idle, I'd press the brakes and slowly let out the clutch until it stalled) I noticed that as the engine started to lug, the pressure would drop to about 3 bar until it stalled. At this point, the needle dropped to zero and the idiot light came on.

The connections to the sender are all still shiney and clean, although the sender hasn't been replaced in the 5.5 years I've owned the car.

Thoughts?

BB.

RedlineMan

Hey;

5-bar is only about 75psi, eh? Isn't it 14.9lbs per atmosphere? I can tell you as a mechanical gauge guy that all of the 944 track cars I tend start up at well over that. Closer to 90-100psi when cold, depending on oil weight. Be they NAs or Turbos, they all read around that range cold.

I don't think those readings are unusual at all, or a problem in the least.

BeerBurner

Well, it could very well be higher than 5 bar. That's just as high as the guage goes. Even when it's hot it'll still idle at 4 bar, which is much higher than normal. I'm starting to think it's the OPRV. Anyone know where that is located?

And for what it's worth, I run Mobil1 15w50.

BB.

michaelathome

Brian!!

Long time no hear! FYI, I am running 10-40 in the 87 and at start-up cold the gauge runs at 5 bar. Warm at idle at or around 3. Warm at about 3000 RPM on freeway above 4. I had 8 hours to do nothing but watch gauges

If you wanna take a look at it bring it on over Sat and we can do it sat as I will be working on the speed sending unit and a few other things as long as parts get here on time.

Michael

BeerBurner

My warm idle had always been between 2 and 3, and the highway idle was at 4 like yours. But now, highway is pegged at 5+.

Plus, I priced those OPRVs... are those really $300???

Anyway, I should be able to make it by there on Saturday. I want to try and remove the valve and clean it saturday morning while the engine is cold. I'll give you a call then.

BB.

bearone

when at operating temp i'll see 3-4 at idle and close to 5 when moving.
20w50 valvoline synthetic.

87951

Kevin Baker

Beer, I was having a problem with excessive oil pressure that turned out (I think) to be bad grounds behind the instrument cluster. The reason I say "I think" is that once I resealed the oil cooler, and changed the oil and coolant it stopped blowing out the oil filters. The pressure readings are still pegging the gauge when cold, and sometimes under hard acceleration when warm. I have noticed that running the a/c will keep the warm pressure more "normal". Most of the time mine is reading a steady 5 bar warm, above 2k rpm, at idle it sits closer to 3.5 - 4 bar.

I have changed the sending unit (before the reseal). Hope that helps.

Eyal 951

ah hah! another one with my symptoms? does it bounce a bit too? I've blown two oil filter gaskets with that pressure! (NOT my OPRV, tried 3 of em)
~Eyal

BeerBurner

It did bounce a bit, but now there isn't enough leeway to tell.

I'll keep you posted on what I find. But if the worst thing I do is blow oil filter gaskets, I can live with that.

BB.

BeerBurner

Hrm, the car must have read Eyal's post and decided that's what it liked to do. When warm, it idles at just below 3 bar, with a cyclic bouncing every second or so. I dunno, maybe I'll just ignore the problem until it goes away...

BB.

Kevin Baker

Yeah, mine's bouncing away while I drive, sometimes. Other times it's rock steady at 5 bar.

Beer, the only "bad" thing about blowing filter gaskets is that when it happens, you get no oil to the rest of the motor. Not to mention the mess it leaves behind.

BeerBurner

Well, I think that the crisis is, for the most part, averted.

I cleaned the connections to the oil pressure sender and the grounds behind the headlight (a search mentioned something about that). I also took out the OPRV and pumped some marvel mystery oil through it to clean it out. Using a screwdriver, I was able to compress the valve in there, and while it was a bit firm, it also moved smoothly the entire way through. I reinstalled the valve and went for a test drive.

Clark's garage said that when warmed up, the pressure should idle between 2 and 3 bar, and be at 4 bar at 5k rpm. It idled at about 2.5 and was approx. 4.5 bar at 5k rpm. However, it never hit 5 bar, whether cold or warmed up at 6k+ rpm, so I think I'm good. Plus, it's possible the oil wasn't all the way warmed up.

So I'll keep an eye on it, but I think I'm good to go.

BB.

michaelathome

Good to hear that things worked out Brian, missed ya at the show, Tony was the only 944 entered. Kinda bites I couldn't take the '87 but parts are on their way.

Sounds like you found a way to have a productive day.

Michael

BeerBurner

I wanted to make it, but I got off to a slow start this morning...

BB.