Calmchaos

I rebuilt the engine 2 years ago or so because the #2 rod bearing did the thing it likes to do.
I don't drive it a lot and I have only put about 15-20K miles on it.

Today car started up normal, drove to the end of my driveway and I noticed the oil pressure gauge wiggling around 4.5 bar. After about 10 minutes of driving the gauge just falls to 2 bar while cruising in 5th gear. Even after coming to a stop, and moving again it just stayed at 2 bar.
It seemed to try to build pressure and eventually getting almost back to 4 bar, but then it fell right back to 2 again.
I left it running and checked under the hood, and I could hear a noise not nearly as loud as the last knock I got, but louder than a lifter noise.

I babied it home and the oil pressure stayed at 2bar the whole time, and it ran a bit rough.

Any thoughts? Anything else I could check before I drop the goddamn steering stuff to get to the oil pan?
Could a loose crank bolt cause a faint knocking noise? It really doesn't sound nearly as bad as it did last time, but the symptoms seem to point to a bearing failure.


The last time I did this job, I'm really really pretty sure that I did everything exactly right. I feel like I took every precaution and triple checked every torque spec. The engine was out and everything was cleaned and all bad parts replaced.

-Brett

Grandpa#3

I'm wondering if you might have a cracked or broken oil pickup tube. There was a post on here a while ago about a repair / brace welded onto the pickup tube to flange.

Cheers,
Larry

carlege

i would check all the other things first. OPRV, Crank bolt. with that little mileage on the engine i wouldnt be convinced that the bearings would be bad

luftpirate

Good luck with that, never a good day to have.

Calmchaos

I just find it very odd that it stays at exactly 2 bar.
Last time i spun a bearing it went from 4bar to 0 and never went much above that. lol

Also would the OPRV make noise? Because I was thinking that to be the problem before I heard the noise.

I just changed my oil from 10-40 (for winter) to 20w50 VR1. The oil filter, and oil plug are not leaking.
I changed it 2 days ago and drove it the past two days with normal pressure.
If that makes any difference.

joonas

My car (944S) spun first #2 after oil change also.

I drive my car usually only open track days or some weekends.

My first #2 went during driving. I did not loose pressure but heard knocking and experienced power loss.
Second time #2 went at the track. First binding feeling and power loss oil pressure was 3 bar, got off the gas and pressure dropped to 1 bar, drove slowly to pit area and oil pressure light came on. Game over.

Both times I used Valvoline VR1 Racing oil. First time semi synthetic 10W60, second time full synthetic 5w50.

Do you track your car or drive at high revs (5000 and more)?
Without external oil cooler oil temps go over 120 degrees C in no time.

OPRV does not make that kind of noise. If some particles are keeping OPRV open it lowers the oil pressure or there is no oil pressure at all.

When you did the rebuild did you use oversize bearings or new crank?

John_AZ

You said the noise was not as loud as before.

Low oil pressure can be caused by a loose front crank bolt.

The noise may be caused by a loose cam gear bolt.
https://rennlist.com/forums/2854326-post1.html

My idle pressure guage "jiggled" between 2.5 and 3 psi until I changed my oil pressure sending switch.
Now it is steady.

Have you checked to see if the OPRV is binding or has failed to cause loss of pressure? Did an OPRV "O" ring fail or "roll over" when inserted?

Good luck,

John_AZ

Calmchaos

When I did the last rebuild I took the crank to the machine shop, and used oversize bearings.
I don't think I have ever hit 5K rpm since the rebuild.
My oil pressure sender is brand new.

I'll check the bolts in the front of the engine today.

Calmchaos

Update::::
Went out there today and started the car up just so I could hear it again. It tried really hard to build pressure for close to 30 seconds then it slowly moved up to 2 bar and stayed there.
I got out and listened to the engine and didn't hear anything but loud lifters.
The sound I heard before could have been caused by a jammed up OPRV. (Found here through search).

I installed my ring gear lock, tried to tighten up the crank bolt just to be sure, and it didn't budge at all at 150+ ft lbs so that seemed good. I took off the alt. belt when I did this just to be sure it was creating too much lateral force.

So went to check the new #1 suspect, the OPRV. It's a 1 piece model.
I really had to crank it to get it to pop loose, and it didn't come out too easily after that.
When I got it out I saw thread marks cut into the side of the OPRV, and the seal at the tip was rolled over.
So it seems it was bound up in there and maybe the switch to heavy oil for the summer caused it to try to open and get stuck open.

Sound reasonable that the OPRV is the culprit?
Can I realign the oil cooler housing with the engine in the car? I don't have power steering stuff in the way.
What seals do I need other than the metal ring on the top, and the rubber ring on the tip?
Any way to test if the valve is still good?

Thanks for the help!
-Brett

xsboost90

i would replace the seals on the oprv-the tip and maybe the crush washer. Then loosen the four bolts that hold the cooler on until you can move it around slightly and install the oprv, then retighten the four bolts. If the oprv is bound up too much it can lock up the internal slide, hold the oil pressure bypass open and maybe start your lifters ticking as they loose oil pressure.

Calmchaos

I have a 1 piece OPRV. Do I buy seals for the 83-86 or 87--> ?
I thought the 83-86 only used the 3 piece valve.
Can someone set me straight on this?
-Thanks

John_AZ

It sounds like you have the "updated" 1 piece OPRV that could be used in the 3 piece application.

If you value your engine, get the OPRV alignment tool to center the OPRV valve in the housing and block to aviod "pinching" of the OPRV and improper operation.

Tech articles to explain the different OPRVs
http://www.944online.com/pdf/oilcoolertech.pdf

GL
John_AZ

Calmchaos

Thank you kindly. I'll get this thing aligned and resealed and hopefully it fixes my problem.

L8_apex

Chaos -
Maybe a bit late with input here. The one check I know of the OPRV is to verify smooth movement in-out of the center plunger, pushed from the inboard tip. If it drags/sticks, that can certainly cause low and fluctuating pressure. Yep, the tip o-ring and crush washer are all that you can replace on the one-piece.

Dare

Actually there's an inner o-ring that can be replaced as well. Here's a thread gives the details: https://rennlist.com/forums/924-931-...-waldo.html#27