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Diagnosis please

What happened is while cruising down the highway without a sound all of a sudden behind me there was a white out - smoke everywhere. Had my 930 towed it had little power to drive it onto the flat bed. The mechanic said it was the turbo. Turbos out but appears to be alright. The turbo rebuilder suggested it could be the scavenge pump.

Obviously everything is full of oil ( muffler, turbo,catch can, intercooler etc) so if the scavenge pump is not working does this mean that there is an engine oil pump that feeds the turbo and without the scavenge pump the oil continues to be pumped into the turbo which then forces the oil up through the intercooler and into the motor ???

Old 11-24-2016, 08:14 AM
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Yes, the engine oil pump is separate from the scavenge pump. The scavenge pump is located on the drivers side, at the back of the cylinder bank, and is driven by a pin off the end of the drivers side intake cam shaft.
If the pin breaks, the pump will not rotate, thus will not pull oil from the drain side of the turbo (turbo oil catch can located beneath the turbo).

That is an easy fix....hope that is your issue.

Mark
Old 11-24-2016, 10:56 AM
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FYI - the reason there is a scavenge pump at all is because the turbocharger sits so low, relative to the engine and oil tank, that gravity draining is not very effective (unlike must other turbo cars on the road).

Mark's explanation of the pump us spot on, but I'm willing to bet his low riding dubs ballsack that the turbo seals and bearings are bad. I don't know how a turbo builder would say otherwise based on a phone conversation. Many people here have tested the scavenge pump operation on their cars and 99.9% of the time, they test good.

Last edited by Rawknees'Turbo; 11-24-2016 at 12:34 PM..
Old 11-24-2016, 12:17 PM
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Hello RawkneesTurbo
So now I have removed the scavenge pump, made a dowl and attached it to a drill and tested the pump only to find it was pumping oil satisfactorily for the speed of the battery drill.
The turbo compressor and turbine wheels spin freely with no noise or shaft play. That is the shaft does not move side to side along its axis but has the tiniest movement when pressing the wheels toward the side of the housing.
Old 11-24-2016, 01:14 PM
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Yeah, the scavange pump will last a long time. It's a gear type oil pump and I think they used the gears from a VW bug engine oil pump.
What kind of turbo you got on there?
Old 11-24-2016, 01:57 PM
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Also check the suction lines on the scavenge pump. I had a loose banjo fitting on my 86 and nearly fixed everything else before I found the loose connection. Sometimes the simple stuff gets you...
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Old 11-24-2016, 03:43 PM
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OK I spoke to the turbo guy again today, after I told him I had run the pump and it is working he asked if there was oil before the turbo.
I put two fingers down into the exhaust and pulled out two very black oily fingers.
So my next step is to remove the crossover pipe between the two headers to see if one exhaust outlet is oily whilst the rest are clean.
Should I find one is oiled up is there any betting as to what I have - a blown oil ring or shot valve as the further I get into this the worst my fears are becoming.
Old 11-24-2016, 08:35 PM
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Hello JFairman,
The turbo is a BorgWarner K27-7006 which apparently ( thanks to Brian RarlyL8 ) is a step up from the K27-7200 and which you told me about the larger housing and turbine. I posted some pics in a reply to you in the thread Turbo numbers?
Old 11-24-2016, 08:46 PM
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It simply is not possible that a broken oil ring could pump enough oil to fill your turbo/muffler/intercooler in that short of time span. After all, the oil would still need to get past your 2 upper compression rings as well...just not a feasible scenario. The same situation goes for a bad valve guide, just no way for that much oil could accumulate in such a short time span. Engines are not that mysterious or complicated.
The issue must be in the oil scavenge system or the turbo seals, nothing else mechanically makes sense.

Mark
Old 11-25-2016, 10:54 AM
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^^^ 100%

If the turbo oil seal(s) go bad for whatever reason, oil is pumped into the turbine housing and muffler, and possibly the compressor side, too - the oil will be "pushed" in the direction of the muffler when the engine is running, but as soon as it is turned off, it will also run backward/down in the direction of the flange where the turbo attaches to the headers (there is a fair amount of oil that continues to flow immediately after shutdown, due to gravity - that's why there is a turbo drip tank on these cars which you wont find on basically any other turbocharged car on the road - drip tank allows the oil someplace to go so that it doesn't just collect in the super heated bearing cartridge and coke up).

Last edited by Rawknees'Turbo; 11-25-2016 at 12:22 PM..
Old 11-25-2016, 12:18 PM
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Great explanation.

Sent from my SM-N910T using Tapatalk
Old 11-27-2016, 03:20 AM
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All explanations offered make sense....but this comment still has me scratching my head:

"...Smoke everywhere. Had my 930 towed it had little power to drive it onto the flat bed..."

A bunch of oil burning off in the hot exhaust shouldn't cause a drastic loss of power....or would it?
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Old 11-27-2016, 05:12 AM
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No, unless to oil run in to motor so not exhaust side only?
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Old 11-27-2016, 06:27 AM
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A hole in the piston would do it

Quote:
Originally Posted by full quack View Post
It simply is not possible that a broken oil ring could pump enough oil to fill your turbo/muffler/intercooler in that short of time span. After all, the oil would still need to get past your 2 upper compression rings as well...just not a feasible scenario. The same situation goes for a bad valve guide, just no way for that much oil could accumulate in such a short time span. Engines are not that mysterious or complicated.
The issue must be in the oil scavenge system or the turbo seals, nothing else mechanically makes sense.

Mark
Old 11-27-2016, 07:06 AM
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Quote:
Originally Posted by smurfbus View Post
No, unless to oil run in to motor so not exhaust side only?
I am guessing there was oil in the motor as the intercooler when removed and placed on my garage floor left a small amount of oil stain which obviously drained out of it.
Old 11-27-2016, 09:01 AM
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Quote:
Originally Posted by jwasbury View Post
A hole in the piston would do it
A hole in the piston.
I do not think I like this scenario at all. I have not dropped the oil from the engine, so if I do this am I likely to find remnants of piston in the oil ?
Old 11-27-2016, 09:08 AM
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Check compression, and do leakdown test. With Failure of a piston you may or may not find pieces when Dumping oil.

Plenty of other things it could be, I mention the piston simply because Mark suggested that it could ONLY be the turbo given symptoms. I'm just offering a potential mechanical reason for the symptoms other than the turbo. Certainly better if it's the turbo.
Old 11-27-2016, 09:51 AM
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I used the term "must be", not "only". The term "must be" does leave the door open to other possibilities, but the turbo/scavenge system still seems like the most likely culprit.

SBK930 did not mention any major engine issue when the mosquito fogging commenced, he only mentioned the cloud of smoke. One would think with a holed piston, you would also notice some impairment in the way it was running. I for one would certainly notice an instantaneous drop of 1 cylinder...just saying. A holed piston would also exhibit damn near zero compression in the offending cylinder, thus greatly reducing it's ability to actually pump oil out either valve track. A holed piston would also drop that cylinder from the ignition cycle, so where would all the smoke be generated from? Remember this all happened very quickly, so short term cylinder events do not generally yield puddles of oil all thru the intake/exhaust tracks. Where as full engine oil pressure flowing past failed turbo seal{s} is very, very messy in short order.

Additionally, potentially fouled plug{s} could easily explain the lack of power while loading onto the tow truck.

But as suggested, a simple compression check would eliminate/confirm the possibility of a holed piston instantly.

I for one am hoping it's the most common scenario, and least expensive end result for SBK930.

Mark

Last edited by full quack; 11-27-2016 at 10:48 AM..
Old 11-27-2016, 10:23 AM
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I am with you on that Mark.

It is certainly a mess and the motor did not have any signs or noise as if it was running without a full deck of cylinders when restarting it. It just blew a little smoke as it was cooled down due to the 2 hour wait for the flatbed.

However I will remove the plugs and check them. And like you said here's hoping for the least expensive fix.

Steve sbk930.
Old 11-27-2016, 11:44 AM
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If indeed it is a turbo seal or scavenge pump failure, then one would expect your engine to not only blow a boat load of oil out the exhaust (hence the smoke) but to also suck up a bunch of oil through the intake and perhaps foul a plug or two. I'm betting that's what you'll find, but let's remember that I'm not a betting man

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Old 11-27-2016, 01:11 PM
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