Air cooled VW zero oil pressure... HELP!!!

[Pontiac_Puller]

Ok, so here's the deal. A 1971 Karmann Ghia came into the shop because of loss of oil pressure. Someone spent some money, because this was a very recent rebuild, and looks to have a few parts thrown at it. Originally a 1600, but now has a big bore kit, twin carbs, and a bunch of extra stuff that's not important right now.

We pulled the engine and cracked it apart, and were horrified by the amount of silicone inside the motor. also it did not have a screen on the pick-up, so it all went through the pump, and all through the oil galleries. To make things worse, this motor has an oil pan extension, and someone must have left a rag inside it during assembly, because it was crammed up the oil pick-up tube.

At this point the problem is obvious. I mean, of course there's no pressure.. no oil could possibly get through!

Everything came apart, and everything got flushed out. Crank and rods were ok, so a new set of bearings and everything else involved, and it's back together. So far so good.

Motors is back in the car, all hooked up, ready to go. We fire it up, and oil pressure is low, but slowly climbs to over 50psi. Still cold at this point, so it's expected. Thought there could be some air in the system somewhere, so starting at low pressure wasn't unexpected. Figured we should let the car get up to temperature, so we let it run. Then the pressure hits rock bottom, barely registering on the gauge. Not good, so car gets shut off.

Seemed pretty sudden, so the first thought was wiring, or the sender. Put a mechanical gauge on it, still nothing. The new gauge hadn't been used for awhile, so it's possible it was stuck, but I'm finding it unlikely that two different gauges failed.

Next thought was the pressure relief valves, so they both got pulled. Didn't find anything wrong, they came out like they were supposed to, and couldn't find any debris or anything that might be holding them open. Now that I think about it, it's possible the springs are backwards, didn't think to check at the time, but would that cause 0psi?

Drained the oil, to check for bearing material. Comes out clean.

Checked the pump, no wear, withing spec.

Been reading up on what causes loss of oil pressure on these things, but so far I haven't been able to find anyone with this exact problem. Even if the bearings were fried, and the pump was toast, it should register SOMETHING, especially at high RPM.

Also, the engine hasn't died yet, how long could one of these run with no oil?

At this point I have no idea what to do. It's my first time working on an air cooled VW, and I already hate them.

Please help me.

[flyingwedge]

Not knowing any better, I would try driving the oil pump externally,(drill motor). Is it possible the pump drive isn't fully engaged ? I don't build Type 1's, but simple check-right ? Good Luck, flyingwedge.

[Pontiac_Puller]

It runs off the camshaft, very hard to prime, let alone check for pressure.

[Unkl Ian]

What oil weight gave 50 lbs at idle ?

Does this thing have a screw on filter ?

[Unkl Ian]

Did you remove all the plugs from all the oil galleys,to flush them out ?

[Unkl Ian]

Cheapo aftermarket oil pumps have a rep for being too small on the OD, so they leak internally.

Also, some crap might have jammed the pump and sheared the drive.
Or the extended pick up broke off.

[lilsumo]

They are almost impossible to prime, the no screen on the pickup is normal so no worries there.
Also throw that deep sump in the trash, all they do hang to low, get busted and ruin your motor.

Did you install a oil filter on it while you had it apart? If not you should have.

You are definitely clogged somewhere, I am taking for granted the line bore is good. They are real picky on the line bore and thrust.

I would have to say that your oil cooler is clogged, you really cant clean them out, you just trash them.

Take your oil sending out completely and turn it over and see if you got any oil coming out there. That is the first place it goes, when the oil is cold it bypasses the cooler, after it warms up it can't keep the pressure relief open anymore and directs it the cooler. I had to guess that you had oil pressure til it hit the cooler and then you may have introduced some more foreign material into the block.

Did you clean out all the passage ways in the block??

[Pontiac_Puller]

Ok, I'll try to clarify.

Engine was first fired on 10w30. After pressure drop, switched to 20w50 to rule out oil.

Yes, everything was pulled apart, so many little chunks of silicone everywhere, the block was thoroughly flushed. Although the oil cooler could be a problem, it was a bitch.

The pickup is in place, pump seems to be engaging properly, oil is making its way through the engine, just extremely slow.

It already had an aftermarket oil filter adapter, so it was cleaned and a new filter put on. Old was was full of silicone. Can't stress enough about how much there was.

The case was bored out a half mill, looked to be on spec. Thrust was within tolerance.

The more I read the more I fear the oil cooler. however if there was a clog, wouldn't the pressure spike? Seriously, zero psi it just baffling. It could be the pump itself, but I cant see anything wrong with it.

Thanks for all the speedy responses guys, I appreciate it.

[af2]

I would have to say that your oil cooler is clogged, you really cant clean them out, you just trash them.

That is all having been there.

[Unkl Ian]

fram filter ?

modified for "full flow" ?

[af2]

fram filter ?

modified for "full flow" ?

LOL!!!!!

[Unkl Ian]

If the cooler is blocked, , the bypass should still allow oil to circulate.

If junk in the cooler, came loose, ....

[Unkl Ian]

http://www.thesamba.com/vw/forum/viewtopic.php?t=280293

[Unkl Ian]

Pic from the link above.

[PFM]

Puller,

If the pump is using a stock pickup and the pump is not sealed well in the case bore it draws in air on the pickup side, zero pressure. If the case over bore was botched zero oil pressure can happen. If the bypass is stuck in bypass zero oil pressure can happen. What was used on the two case halves when it was reassembled? Clearly silicone was used in the past but what this time? If it takes up space the main bore is not round now.

All that said my bet is a leak on the pickup side of the pump. Air in no oil out. A leak behind the pump inside the case on the pickup side is not un common.

Sounds like you really got yourself into a mess.

Stay tuned,

PFM