RennBod

My friends 944 turbo has developed some unusual problems.

When you start the engine from cold, it rattles and has NO oil pressure... let it run for a few seconds (that seem to take forever, but its betweem 5 and 30 seconds) the oil pressure gauge shoots up to 5 bar, and the engine stops sounding like a bag of nails.

What could it be?

Would the oil pressure relief valve cause this?

Could it be the oil pick up pipe leaking?

What stops all the oil draining back into the pan when the engine is stopped a while?

We have changed the oil filter (I thought it might be the check valve), and it didnt help one bit.

its a 1986 model if that helps.

GlenL

Could be a worn oil pump.

What weight oil is he running? How many miles on the car?

ahofam123

My delayed oil pressure was the cause of the pressure relief valve. I replaced the 3 piece valve with the updated 1 piece retrofit valve and now build oil pressure almost instantly.

RennBod

GlenL
Oil he has in it is 5w40 synthetic, we were thinking of trying changing the oil for some mobil 1 motorsport 15w50 synthetic oil that I use in my cars to see if it helps.

ahofam,

Did your car have the exact same symptoms?

Anyone else have these symptoms before? I want to try and narrow down the possibilities before we start pulling things apart.

Which is the oil pressure relief valve which has the replaceable o-rings? is that the old 3 part style or the new style?

Is there anything which can be done for the old style apart from just replacing it with the new type?

were the old type 3 parts valves fitted to turbos?

Peckster

Loose nut on the crank? There have been similar posts.

I wouldnt let it ruin that long without oil more than once.

Zero10

Hmm, mine does somewhat the same thing, just not for as long.
On cooler days, it will run 5 or 6 seconds with no oil pressure, rattling like crazy.
Checked out the OPRV, cleaned and re-installed, no luck.
Checked torque on crank pulley, just fine.

It all started right after I bought the car. It had been sitting for 8 months before I bought it. We started it up, everything was great. I decided to change the oil after about 2 days of driving it, and put in a can of engine flush, since the old oil was terrible looking, and had been in there for quite some time. Ever since then, it's done this.

ahofam123

After sitting overnight, my car would take ~ 30 seconds to build pressure. I removed the three piece valve and wetsanded it with 1500 grit wetsand paper. That brought the build time down to ~5 seconds. I finally just gave in and bought the one piece retrofit valve. I believe that the three piece valves are found on turbos and NA's up until 1987. The three piece valves only have the crush washer whereas the one piece valves have the crush washer and an o-ring on the end.

Kevin Baker

If the car in question is an 86 or later turbo, it will already have the updated, one piece OPRV. If he is having a delay in oil pressure, he needs simply to replace the two o-rings in the valve. Do a search on the many threads I have started/posted to. Search username=Kevin Baker, subject/keywords= OPRV. You should bring up a thread from about a year ago, where some generous lister provided me with a diagram of the valves, and part #'s for the o-rings involved. We are talking about =/- $10.00 usd.

RennBod

I am in the middle of removing my oil cooler from my 86 lux at the moment, but will be taking out the OPRV from the turbo this weekend.

Anyone able to give me the part number for the o-ring if it is a one part OPRV?

Or, can anyone tell me the o-ring size and material type? I have a seal wholesaler around the corner who could probably match it

mark944turbo

I have the same symptoms, but I get around the problem by just cranking the motor without letting it start for 10 seconds if it has been sitting for a while. This builds a little oil pressure before there is any load on the bearings. After doing this it builds instantly on startup.

I will buy those o rings too and see if that was the problem. Thanks!

Mike B

I'm with Peckster...Any recent work on the engine?

Zero10

Given that I have the same issue, and I have just replaced the O-rings on the OPRV, I'm inclined to think the problem is elsewhere. It sounds rather like the oil pump losing it's prime.
I know there is the anti-drain valve in the oil filter, I use nothing but Mahle or Porsche filters, so that's not it. But, I heard there was another check valve in the block somewhere?... I'm wondering if anybody knows anything about it.

GlenL

Looking over the PET, cause this interests me and I haven't had my 944 engine apart...yet, it looks like there is no check valve for oil in the head. There are relief valves for the oil cooler and towards the back of the head. I think those just vent off excess pressure. (Anyone?)

Sounds like it might be a worn pump amplified, for some folks, by thinner oil.

RennBod

Aparently the engine was replaced just before he brought the car, with a good used one.

Also, apparently the sump gasket and belts were changed before they fitted the engine... I just hope they did up the crank pulley (I will check that) but more importantly, I hope they didnt damage the oil pick up tube (could that cause his problem? I hope not, I dont want to have to go dropping the sump!)

I think the first thing we will do is check the OPRV and drop the oil and replace it with some Mobil one 15w50 that I use in my 86lux, the 924 and the 911SC/993 hybrid and see if that sorts it out.

Magown

This is incorrect, all 86's came with the junk early 3 piece valve. 87+ got the update right out of the box.