Oil Pressure while Boosting

no1biscuit · 10-10-2001, 04:46 AM

I was watching my gauges this morning on the way to work and I noticed that when I boost heavly my oil pressure goes down (like from 5 to 3). Is that normal?
Thom

Goku · Goku's Garage

In my turbo it is usually the oposite.

no1biscuit · 10-10-2001, 09:31 AM

Wierd?

Goku · Goku's Garage

Well my car has a dead battery and i'm having a very busy week. Huge project presentation today. So maybe when i get it running i'll try running it as full boost to see if my oil pressure drops off at all. Give you an update soon hopefully

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88' 951
2k VW Golf 1.8L TURBO
Reluctantly crouched at the starting line...

seb928s · 10-10-2001, 10:21 AM

I'm going to go drive my 951 and I'll tell you once I get back.

seb928s · 10-10-2001, 11:01 AM

It's at 5 bar when I boost.

no1biscuit · 10-10-2001, 11:17 AM

So what does that mean?????
Now what is wrong with my car?

lordgrommit · 10-10-2001, 11:27 AM

Well I had the same thing on my 951 the oil pressure would drop to about 4 when hard boost... I don't know about the new one till I get it back on the road hopefully this weekend.

Matt

no1biscuit · 10-10-2001, 11:32 AM

LordGrommit
So is that OK, Then? Or is there something wrong?
Thom

ae1969 · 10-10-2001, 11:49 AM

I would think ...there is something seriously wrong....

at full boost.... your rpms are quite high.... and why you are loosing pressure, when it should be at its highest?? is beyond me

would this happen prior to a blown head gasket... oil cooler seals.....?????

wolfrpi · 10-10-2001, 12:56 PM

Probably need a new motor - I'll paypal over $400 for the car if you want to unload it.

Erick

no1biscuit · 10-10-2001, 01:02 PM

Ha Ha Ha.
I don't think it is that bad.
Thom

Macabre · 10-10-2001, 02:25 PM

Mine drops a little bit too. Certainly not from 5 to 3 though.. more like 5 to 4.5. It only does that around 3000rpm and stops doing it once I'm closer to 4k. I see it happen a lot on the freeway..

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'86 951 Graphite Metallic/Tan

Lawrence Coppari · 10-10-2001, 02:26 PM

I don't think oil pressure should drop when boost arrives. Mine has never done that. Only time oil pressure drops is after several hot laps on a hot day - this is track driving. Then it gets down to 4 bars at high rpm. Lower at idle but I don't remember exactly what.

Dave951 · Dave951's Garage

Wow, that's a new one. These are just shots in the dark. Help me with the logic.

It seems that as the turbo spins faster and faster, it would let more oil blow by the seals. This would lower the pressure, but I can't imagine it dropping 2bar. You would definately notice smoke in the exhaust.

If you did have a headgasket break that only opened up under boost, letting oil leak by, I can imagine that too. However, it seems like you would have to lose a lot of oil in that situation as well.

Maybe it is just some wierd electric drain on the system under boost, causing the pressure gauge to display lower?!? You should try and hook up a mechanical gauge to doublecheck the electric one.

I would just be careful while you're trying o figure it out. Maybe no driving with the radio is in order, so as to let you hear the trademark tick-tick-tick of good ole #2.

Dave

wolfrpi · 10-10-2001, 02:54 PM

Mine wouldn't drop at all. It would pretty much peg 5 bar and stay there until 7000 rpm. I'd check your compresssion first on all four cylinders (its quick and easy). If its bad (significantly less than 150 psi), you're in big trouble. Also check your voltage to the oil pressure switch and the related grounds. Check the tightness of the crank pulley also. Finally, use 20-50w to protect it in the future.

Erick

no1biscuit · 10-10-2001, 07:05 PM

You all know how to make me feel good.
It is not burning more that .5-1.5 quart every 3k Miles. I have no antifreeze in my oil. I will verify the exact drop in oil pressure next week when I get back to town. I hope it is the electrical problem......
Thom
P.S. Thanks for all of you help...

lordgrommit · 10-10-2001, 08:26 PM

I think it's prob a electrial thing ... the dme controls the boost gauge. when your on it I think something is wrong so the gague gets the wrong reading.. Wolfrpi had an aftermarket Boost gauge the stock ones are notorius for being wrong

Matt

C.J · 10-11-2001, 04:48 PM

Could be a low oil situation causing the pump to be starved for oil when the oil is forced to the back of the pan.

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CJ

scottewid · 10-12-2001, 05:06 AM

Just checked mine: stays at 5bar on the oil gauge during full 2bar boost on the turbo gauge. Only drops to 3bar on the oil gauge when engine is hot and at idle.