944 oil pressure relief valve

[keepsoj]

Does anyone know what it does? What happens if you run the engine at low speed without it? I want to trouble-shoot it by removing it--is this safe? What will happen? Thx.

[John_AZ]

Welcome,
Brief advice
1-Read all of www.clarks-garage.com. We have it bookmarked.
2-Try the search feature as well
3-Ask more questions
4-Tell us what you own on the signature line
5-When was the last time you changed your belts-SoCalDriver
Good luck

John_AZ
1988 924S + 1987 924S

[hpservertech]

Am I correct in understanding that you want to run the engine without the OPRV to trouble shoot it?

Hate to ask a dumb question, but why?

And when you changed your belts has nothing to do with it either.

[John_AZ]

hpservertech,
Item 5 is a private tribute to one of the best members on this forum. Do a search.
John_AZ

[hpservertech]

I realize that, but the OP might not. he asked a simple question, not a history lesson on others of this site or rennlist.

[keepsoj]

hpservertech: Nothing to do with the belts> I'm having oil pressure problems. I've changed the relief valve and I think it might be sticking (yes, I used the proper alignnment insertion tool) So I wanted to remove the valve (and plug the mounting hole) to see if that's the problem. Do you know what it does, or what will happen if it is removed? Clark's Garage says you can remove it and leave the hole open to see if oil comes out the hole. I'm guessing that it limits pressure at higher revs--do you know? Thx ~joe~

[944 Ecology]

If you remove the OPRV, you will have no oil pressure.

I highly recommend against doing so.

[Gary2397]

Sounds like you are not getting oil pressure reading on your gauge. Chances are you are not using the right oil filter or your oil pressure sender could be bad. Sometimes using low quality grade of oil will give you bad reading on the gauge too.


Also, you might want to make sure that oil pressure relief galley is align correctly.
You can find out is to remove the valve and insert the oil pressure sleeve alignment tool to its galley.

[djnolan]

I am having trouble removing my OPRV prior to removing the oil cooler housing.

It is a 17mm nut that turns out counter-clockwise, lefty loosy, correct???

So far I have only succeeded in rounding it off some.

Any suggestions?

[aj951]

IIRC it is a 24mm or 15/16.

A.J.

[Slam]

Remove the housing with the OPRV retaining bolt in place if you have to. Then you can take the housing to a shop and have them remove that bolt.

If you plug the OPRV hole you run the risk of blowing your oil filter off the boss. If you remove the OPRV you'll get no pressure. How's your crank bolt? If it's not torqued properly (145lbs IIRC) you'll not get proper pressure.

HTH

[djnolan]

Here is a picture. Not sure what you mean by the crank bolt or if I even have the correct location of the OPRV. Is the larger rusted bolt the OPRV? Where is the crank bolt?

[Vfourfast]

What are the symptoms of the problem your are you having?

the earlier 944s had a smaller hex and the parts of the oil Rv come out in individual pieces. The later cars had a one piece RV. The best way to get it out is to use an impact gun. Using a socket and breaker bar tends to twist and round off the corners of the nut.

Some symptoms.

If the valve is sticking slightly open because there is a bit of debris the oil pressure will be good above 2000 rpm but very low at idle.

If the spring is getting week the maximum pressure will be around 3 bar but act fairly normal around idle.

A cracked oil pickup will cause the oil pressure to build up very slowly because the pump is sucking air.

[HondaDustR]

Originally Posted by keepsoj

Does anyone know what it does? What happens if you run the engine at low speed without it? I want to trouble-shoot it by removing it--is this safe? What will happen? Thx.

What it does is limit the oil pressure at higher rpms using a spring and piston. If it sticks open, you'll have very low oil pressure, except maybe at high engine speeds. If it sticks closed, you will blow out your oil filter and who knows what else.

What will happen if you remove it and run the car is the oil will gush out that hole like a severed artery!

I don't remember what that rusted bolt does (holds on the oil cooler housing, I think), but the OPRV head has a smooth surface, is rather large (definitely bigger than 17mm), is a standard thread direction part, and should be right near that bolt you are referring to.

[Tidybuoy]

Originally Posted by djnolan

Here is a picture. Not sure what you mean by the crank bolt or if I even have the correct location of the OPRV. Is the larger rusted bolt the OPRV? Where is the crank bolt?

That is definately NOT the oil pressure relief valve - but you are in the right area. The OPRV is a much larger very flat looking bolt - you will not see any threads like you do in your photo. If that "is" the OPRV, then it definately looks like it's the wrong one.

Here's a photo of my old OPRV - mine is for an '88:



Vern

[aj951]

djnolan,

It would help if you put information about your car in the signature line, such as the model year and if it has any modifications.

Your picture looks like you are in the right place but as Tidybuoy said, that doesn't look like a later model year (85/2 and up) OPRV. I have an 89 year model and my OPRV looks just like Tidybuoy's.

The crank bolt keeps tension on the oil pump drive gear, which is needed to keep the oil pump working properly. I think the person who posted that suggestion about the checking the crank bolt torque was assuming you were having oil pressure problems since you are wanting to remove the OPRV for troubleshooting purposes. The Porsche Service Manual states the crank bolt should be torqued to 155 ft-lbs in order for the oil pump to work properly.

Good luck with finding your problem, whatever that might be.

A.J.

[djnolan]

My purpose for removing the OPRV is to replace the oil cooler seals. I got the bolt loose with wd40 and wire brushing. I have a late 85 automatic. Here is my OPRV. It looks like the older three peice model. My oil pressure was fine but I will pay close attention when I get her running again. Thanks!

[onZedge]

That oil cooler gasket kit does not come with new o-ring seals for the OPRV. You have to buy the two o-rings separately.

[Tidybuoy]

Well, I learn something new every day. The original picture definately looked like a bolt & nut but the last picture clarifies everything....thanks

[djnolan]

The seal kit didn't fit the way I expected. the plastic ring and the spacers did not fit the boss like I expected. I ended up being able to use only the gasket, two o-rings and the rubber ring. The OPRV has a metal washer I will re-use, and not an o-ring.