Porsche Repair: oil pressure, willing volunteer, head gasket

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I have a 1984 Porsche 944.  Recently replaced a bad head gasket.  After starting noticed the oil pressure was very low.  Re-checked oil level and it is full of oil.  No oil found in the oil filter though.  Do you think it is the oil pump?  What are the possibilities?  I have not worked on an oil pump like this before so not exactly sure if that could even be the problem.  Appreciate any help you can lend on this matter.

---Rob
Answer -
Rob,

Just to remind you, my expertise lies in the older 356 models.  Luckily, many early designs/concepts have lasted since the early 50's and appear in revised forms on 911's, 914's 944's, Boxsters, etc.  Where this happens I'll promise to try to give you the best answer I can.

I'll assume that you did not touch the oil filter, its mounting plate, or the oil pump cover when you replaced the head gasket.  If my assumption is wrong, please let me know.

Here's what I'd suggest.  Take the spark plugs out and disconnect the coil wire.

Step 1. Here's the messy part:  leave the oil filter off; turn the engine over a few times while a willing volunteer watches what happens and moves a pan to catch any oil.  Try to guesstimate whether the oily mess is enough to fill the oil filter, if you had kept turning the engine over longer.  

Step 2. If the mess is adequate, replace the oil filter and turn the engine over some more, until the filter is full and you get normal pressure.  It really shouldn't take too long.  Then you can replace the plugs, etc.

If Step 1 was unsuccessful and there's no oil coming from the oil filter plate, this is a puzzler.  Unfortunately I don't have a schematic that shows the oil flow, this would certainly be helpful.

Let's try the above steps first.  Please get back to me with whatever you find.  I'm curious now.  Good luck.

Dave


Thanks for your response Dave.  Unfortunately there was no mess at all.  I don't have a schematic for the oil flow either.  I guess I'm gonna have to drop the engine out and take a look.  Unless you have any other ideas.  

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Rob, this is unbelievable.  

I just want to confirm that you weren't anywhere near the oil pump in your gasket replacement, right?  And before the head gasket problem, oil pressure was not an issue, right?

I'm trying like crazy to come up with a logical answer.  None.

I keep thinking about the camshaft belt and the balance shaft belt and how they both go around the crankshaft right in behind the oil pump.  And you had to remove the cam and remove the belt to get deeper into the head itself, didn't you?

So when you start it up, or turn it over, you don't get any really nasty sounds...and you're sure the camshaft belt went back on its sprocket exactly as it was.

There really can be only two other alternatives:  the oil pump died, or there is cylinder head gasket scrapings blocking the oil flow.  I'm not convinced either of these is the answer...but I'm plum out of ideas.

Ya got me on this one.  Please let me know when you find out what the problem is...I'll want to tell my future grandkids the story of Rob and his uncooperative little 944.

Dave

Thanks for your help on this so far Dave.  I know what the oil pump looks like and the parts involved.  It is different than most of the pumps I have seen.  Can you tell me how it's driven?  It appears that the oil pump sleeve and the crank shaft are both smooth.  Should the sleeve have an interference fit or should it slide right on?  

Answer
Rob...Am I on candid camera?  I have been staring at pictures of your engine trying to compare one to another and all I keep doing is scratching my head and looking dazed.  The gear (sleeve) looks like it slides on the crank snout fairly easily.  There also is an o-ring between the gear face and the crank pulley.  It's hard to imagine that when the crank turns it turns the gear just from the torqued pressure of the pulley.  Like you, I don't see how else it's driven.  Wish I could be more help here, but I've not been 'lucky' enough to disassemble one of these engines yet.

I know you'll find the cause of this mystery ailment...be patient.

Dave