daniel951

i been having the same problems after having a blown headgasket. WHen first start it up i would not have oil pressure for a long time so i went the store and got some engine cleaner noisy lifters crap threw it in there and ran it for a little bit and it helped alot. Then after that it was still doing it in the morning but not as bad so i put heavier oil in there and no problem now. I checked the OPRV but didn't notice anything wrong but running thicker oil seems to fix it but it takes longer to warm up now though

Kevin Baker

This is the info I was refering to:
The '99 edition of the Parts & Technical Reference Catalog for models 934,944 and 928: 1977-1988 has a detalied technical bulletin (#3) discussing the differences and replacements. It is six pages long. I don't have a scanner or I would send it to you.

From the bulletin these are the replacement part numbers;

83-86 944, 944 turbo
1. Valve is 944 107 035 11
2. O-Ring is 944 107 935 11
3. Seal Ring is N 043 815 3

87+ 944, 944 turbo, 944S
1. Valve is 944 107 035 01
2. O-Ring is 944 107 935 01
3. Seal Ring is N 043 815 3

Let me know if you need anymore info from it.

Kevin Baker

Diagram and part numbers:http://boards.rennlist.com/upload/Replacement_OPRVs.gif

RennBod

Been a bit busy with my 86 Lux at the moment to look further into the problem with the turbo oil pressure. But now the lux is fixed (I hope) I will be looking at the turbo in the next 3 or 4 days.

Anyone out there know the size and spec of the o-ring for the single part OPRV's? where does the second ring go? I noticed an single oil ring at the end of the single part OPRV on my lux, but didnt notice a second one.

As well as replacing the o-ring (if its a single part one) I will also run an engine flush first and then once the OPRV is re-o-ringed, or replaced with a single peice one, I will fill her up with a thicker oil.

I will keep you all posted

RennBod

A bit of an update, over christmas my local Porsche friends and I have been having a bit of a session helping each other work on our cars.

The 944 turbo, we have changed the oil filter (in case it was a filter check valve) and removed what turned out to be a 3 peice oil pressure relief valve.. we cleaned it up a bit and re-installed it... once we fired it up, the oil pressure came online right away... the next morning the oil pressure also came up quickly... BUT, then a couple of days later we are back to the same problem...

The next plan is to try some thicker oil (probably mobil one motorsport 15w50) and see how it goes... if that does not work, we would move onto changing the oil pressure relief valve with the newer 1 piece design...

Anyone have any other thoughts?

gmsracing

I have the same problem with my '86 951. On cold start up it will take a second or two to build pressure. On hot start up it builds pressure immediately. I've done:

1. Replaced oil filter several times. Didn't help.
2. Polished slightly scored origninal 3-piece oprv. Didn't help.
3. Checked torque on crank pulley.
4. Replaced 3-piece with 1-piece oprv. Didn't help.
5. Pulled oil pan and checked pick up tube. Was fine and not cracked. Replaced oil pick up tube rubber gasket. Didn't help.
6. Tried different types of oil. Didn't help.
7. Took it to a mechanic. They didn't have a "magic solution" but they suspect it could either be a back check valve in the head, or the sealing glue used in the oil pump has cracked and is allowing for the car to loose it's prime.--I haven't acted on these suggestions yet.

So, I haven't solved anything yet! Let us know what you find out. I know several other people who are having this problem.

Peckster

If cleaning the valve fixed the problem for a couple of days, that's obviously the culprit, not the oil.

blackcube

I had the same problem on my '83 NA. I resealed the pump, replaced the pump, resealed the cradle, replaced the OPRV and finally noticed a hairline crack in the oil pickup tube. Under vibration the crack would widen and the pump would lose prime. After the engine stopped, all oil would leak down and it would take 30-60 seconds to build up upon startup. Porsche didn't have a pickup tube in the US at that time (1989) so I had the old one welded with a tig machine. I'm still running the same tube. Check the pickup tube very carefully.

Granite 944

This is just a segment of a TSB regarding this issue. Applies mainly to the early cars. I'll bet this is what blackcube was thinking in the begining. I've never had this problem, but bet it would be REAL easy to miss a hairline crack in the pickup tube.

KuHL 951

I have had the same problem but have resolved it for now with a new starting procedure, doesn't make sense but it's worked everytime now for the last 2 weeks when it would take 15-30 seconds to build up for about a 1 week period. I let the fuel pressure build for 10-15 seconds with the key on so the car doesn't turn over so many times like before (I know I have a leaky fuel check valve near the tank). I'm still not convinced there are 2 o-rings on the one piece valve. Here's a couple pics of the two different OPRV's.
1986 1-piece conversion for older 3-piece OPRV

1987 1-piece OEM OPRV

Granite 944

2Tight, have you looked at this thread? https://rennlist.com/forums/showthre...44#post1812944

Those are the best pictures I've ever seen of those 1 peice OPRVs. Gotta save those.

mark944turbo

I am telling you, if you want a cheap fix, install a fuel pump cut switch, and crank the car over without fuel for 5 seconds before cold starts. Sure it is a little bit of a pain, but pressure builds and you will not have any bearing problems.

KuHL 951

No, I didn't see Tom's recent post on that other OPRV thread I posted in until you linked it. Thanks, that does clear up a lot of confusion, at least on my part. For the life of me I still can't figure out why the oil pressure problem on mine goes away when it fires up on the first couple of cranks. When fuel pressure needed to build it would take about 10 seconds to start up and then another long wait for oil pressure to build. If my pick-up tube was cracked I would think the problem would be consistent and not intermittent as it is. I have the replacement 86 1-piece conversion valve I pulled from my spare 86 motor but haven't put it in yet since my problem has "resolved" itself for the time being. I'm wondering if that 2nd o-ring should also be replaced before I do the swap? I only bought the o-ring for the tip, guess I order it just in case.

KuHL 951

Mark,
Trust me I've thought of that before but like I mentioned mine would not build any oil pressure when it cranked for 10 seconds or so at starter speed; only when it turns over quickly which it does when I let fuel pressure build. I have no idea why the two have anything to do with each other unless the pick-up tube only sucks air at the low cranking speed. These cars are sure quirky when it comes to oil pressure!
Steve

mark944turbo

I see, just one more comment. I do not see pressure build on the guage from cranking minus fuel, but it does build immediately when the fuel start afterwards.