KlineS147

Bought my car 3 years ago and the oil pressure gauge never has worked properly. So last spring, i bought a new sender from pelican, and i installed it and it is still pegged at 5 all the time.

I think i've read every article on rennlist and pelican about this problem and i having a huge disconnect maybe i'm thinking too hard about it...

When the ignition is on, but engine off the gauge is slightly above 0, when the car is running the gauge is at 5 all the time, i've never seen it move. First response seems to be switch the wires but from what i read this would cause the gauge to read 5 with the engine off.

Next response seems to be bad unit, now i did just replace mine(not saying it couldnt be bad, i saw 2 posts where new ones came faulty), but i'm still uneasy about calling my new sender bad.

Final response and the one i think seems to be the problem is the OPRV. This is a whole new topic.... I have an 87' would guess its a late style and i'm assume this until i can check it on friday for sure. If it is a OPRV problem what exactly would cause high oil pressure? People seem to have other problems with high oil pressure such as popping oil filters or dipsticks, i dont have these problems but would leaking front end seals negate the blowing off filters or dipsticks?

Can i clean and re-use the OPRV or must i replace it? I hate to replace it because i just spent $500 for timing belts, waterpump and all new seals and races, and it doesnt seem to have any other ill effects other then a bad gauge reading....

I'm so confused i dont know where to start or what to do, please any advise would be greatly appreciated. Thanks Steve

Reimu

The 87s actually use 2 different OPRVs depending on what time of the year it was built. Don't feel bad, took me 2 oil filter seals to finally figure that one out. I had it mixed with one that came from a later car.

Even with a stuck OPRV I don't think it'd be pegged at 5 when warm.

JBrown

is ur oil pressure sender unit (think thats what its called it have a spring or a valve in it) lined up properly if it is not and it is crooked could cause this problem

luftpirate

You could still have a failing OPRV and not be blowing dipsticks or popping seals. It just might not be to that extent. When you remove the OPRV and inspect it be sure the plunger operates without binding. Also make sure there is no scoring on the plunger. I would also invest in a cheap aftermarket mechanical gauge to double check against your stock gauge. Just get a cheap Autometer or VDO to test it with, or rig up in your glove box for piece of mind.

When I rebuilt my oil cooler I tried to rebuild my OPRV. The plunger had light scoring which I was able to polish out, but I was never able to source the correct O-Rings to rebuild it. So it's laying in parts on my work bench and 250 dollars later I have a brand new OPRV I bought off Ebay, NOS. My Oil pressure is 5 bar warm under load and 3 bar at idle. I'm frankly very glad I went with the new OPRV and I know everything is correct.

divil

But you tried switching them anyway right?

Techno Duck

On the pressure sending unit, hook one end of a voltmeter up to the post for the gauge on the sending unit and the other end to any ground point. Check the resistance #'s you get..

Cold idle will probably show 185-250 ohms, warm idle should be somewhere around 100 ohms.

If at warm idle you are getting anything over 200 i bet your new sending unit is bad.

One of the threads you read might have been mine, i had a brand new URO brand sending unit bad right out of the box a few years ago.

arthropraxis

It is hooked in with the ! light. If that bulb is out or removed it will stay pegged at 5.

John_AZ

Rennlist sponsor 944online has a PDF explaining the different oil cooler housings and OPRVs:

http://www.944online.com/pdf/oilcoolertech.pdf

Can I clean and re-use the OPRV:
When you pull the OPRV out of the oil cooler housing, you should replace the 2 "O" rings Also get new aluminum crush washers or the OPRV will drip oil.

Carefully press the inner valve in. It must move freely.

Here is a TSB on the procedure I have posted many times. The last "box" explains that the alignment of the OPRV is critical. If the "new style" OPRV alignment tool was not used, the OPRV can bind.

GL
John

divil

There. I knew I had seen this post somewhere but it took me a while to find it!

I am having the exactly same symptoms myself which is why I found that in the first place.

doabarrelroll

I had a very similar issue, if not identical. It turned out my OPRV was basically non-functional. Upon switching the OPRV with a known good one, I got normal oil pressure.

IIRC, the wires swapped will cause the gauge to peg at 5 bar at key on. Normal operation means that it will sit around 1 bar at key on, then while cranking the gauge bounces a bit and then when the engine fires, it should peg to 5 bar.

If you remove the OPRV, check the compression of the piston? inside the OPRV. My non-functioning OPRV seemed to be very easily compressible.