Sudden loss of oil pressure - potential causes?
07-20-2010, 06:01 PM
#16
Burning Brakes
Thread Starter
I don't like the direction this thread is headed. The oil pressure failure happened immediately after an oil change, so clearly the shop caused a problem. There's absolutely no way a properly-done oil change can cause this kind of failure. No way. Period.
I still think Garth was right, that they accidentally pulled the pressure relief parts (happens all the time!) and botched something there. They clearly did *something* wrong.
My worry is that by giving them the car back, you'll never learn the truth but instead get stuck with a $7,000 engine repair bill.
I still think Garth was right, that they accidentally pulled the pressure relief parts (happens all the time!) and botched something there. They clearly did *something* wrong.
My worry is that by giving them the car back, you'll never learn the truth but instead get stuck with a $7,000 engine repair bill.
Given the lack of any evidence to that end, however, I am not prepared to accuse them any more than they (I would hope) would jump to accuse me.
The gentleman who is overseeing the effort, currently, is not exactly inexperienced. He is also a member of RL.
There are a few more areas which can be checked (relatively) easily.
Sigh...
07-20-2010, 06:02 PM
#17
p.s. oh and here's one possible mistake: if they unhooked the oil return line to gain access to the small oil filter, maybe they stuffed a rag inside the tube so it didn't leak all over them. Then somehow forgot to remove it when re-attaching the oil line.
Hey, it's a longshot but again, there aren't too many ways they could have caused this problem.
Hey, it's a longshot but again, there aren't too many ways they could have caused this problem.
07-20-2010, 06:29 PM
#18
Burning Brakes
Thread Starter
Next steps (to the best of my ability to relay them accurately):
1.) Remove intake and exhaust covers; return tubes accessible at cam housing; can see oil pump (or potential blockage) from there.
2.) Check over-pressure safety valve.
2nd tech stated that he heard "rattling" when the engine was turned. I would consider this normal for any engine if there is no oil pressure... need to examine repair manuals tonight so I can better visualize the system.
We're brainstorming at this point so have at it...
07-20-2010, 06:38 PM
#19
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Best bet is to take the car back immediately and take it to another shop to have the engine torn down. Or else be prepared for a $10k bill.
07-20-2010, 07:49 PM
#20
Burning Brakes
Thread Starter
Even if that guess was right, we'll never know. No shop on earth will admit they messed up and eat a $10,000 repair bill. Just won't happen. They'll find some "mechanical failure." I hate to seem cynical, but that's just how it goes.
Best bet is to take the car back immediately and take it to another shop to have the engine torn down. Or else be prepared for a $10k bill.
Best bet is to take the car back immediately and take it to another shop to have the engine torn down. Or else be prepared for a $10k bill.
The speed at which a rebuild was brought up during the course of discussion gave me significant pause but I do not yet have enough information to draw any plausible conclusions; let alone make rational, informed decisions.
If he is on-site Saturday (and the cause is not found by then), I'll be stopping by with a six pack to try and make sense of everything. I need to see something to fully understand it.
07-20-2010, 08:01 PM
#21
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I wonder if something fell into the tank and plugged the inlet to the line to the oil pump? That could also be a cause...for example the lid off a oil can dropped into the tank and plugged the inlet.
BTW, you can see the oil pump gears if you remove the oil feed tube...you can check that its clear, and that the pump layshaft is still connected (i.e. not sheared for some reason). If a rag got sucked in for instance, that would jam the pump and perhaps shear the coupler to the oil pump.
Cheers,
Mike
BTW, you can see the oil pump gears if you remove the oil feed tube...you can check that its clear, and that the pump layshaft is still connected (i.e. not sheared for some reason). If a rag got sucked in for instance, that would jam the pump and perhaps shear the coupler to the oil pump.
Cheers,
Mike
07-20-2010, 08:13 PM
#22
You say you coasted to a stop, with zero oil pressure and warning lights.
Is it at all possible that the motor stalled and it came together in your head as loss of pressure?
The mind can play tricks on us.
Driving down the road, radio going... red warning light in your peripheral vision. Fast glance and see no oil pressure switch key to 0 position. I can see it happening.
Is it at all possible that the motor stalled and it came together in your head as loss of pressure?
The mind can play tricks on us.
Driving down the road, radio going... red warning light in your peripheral vision. Fast glance and see no oil pressure switch key to 0 position. I can see it happening.
07-20-2010, 09:32 PM
#23
Burning Brakes
Thread Starter
You say you coasted to a stop, with zero oil pressure and warning lights.
Is it at all possible that the motor stalled and it came together in your head as loss of pressure?
The mind can play tricks on us.
Driving down the road, radio going... red warning light in your peripheral vision. Fast glance and see no oil pressure switch key to 0 position. I can see it happening.
Is it at all possible that the motor stalled and it came together in your head as loss of pressure?
The mind can play tricks on us.
Driving down the road, radio going... red warning light in your peripheral vision. Fast glance and see no oil pressure switch key to 0 position. I can see it happening.
I wonder if something fell into the tank and plugged the inlet to the line to the oil pump? That could also be a cause...for example the lid off a oil can dropped into the tank and plugged the inlet.
BTW, you can see the oil pump gears if you remove the oil feed tube...you can check that its clear, and that the pump layshaft is still connected (i.e. not sheared for some reason). If a rag got sucked in for instance, that would jam the pump and perhaps shear the coupler to the oil pump.
Cheers,
Mike
BTW, you can see the oil pump gears if you remove the oil feed tube...you can check that its clear, and that the pump layshaft is still connected (i.e. not sheared for some reason). If a rag got sucked in for instance, that would jam the pump and perhaps shear the coupler to the oil pump.
Cheers,
Mike
07-20-2010, 09:36 PM
#24
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Of course, I mean pull the DME and crank the engine over while looking into the oil feed tube hole to see the oil pump turning over...but it means draining the tank of oil.
07-20-2010, 09:50 PM
#25
Burning Brakes
Thread Starter
If the tank needs to be drained again, so be it. They drained it once, already. DME was pulled and engine was cranked to confirm lack of pressure this morning, I believe.
Im really far from a mechanical genius, but I simply can *not* figure out what is causing this. They have already looked at everything I thought to check - in addition to what was suggested by you guys - and they know a heck of a lot about these cars.
If I have to tear apart a perfectly good engine, I will be extremely displeased.
75,000 miles, no CEL, no smoke, not a SINGLE leak, ZERO oil consumption under normal driving conditions, a measly half-quart burnt during a track weekend, one of the strongest N/A 3.6's I've driven... ...banging my head against a wall, here...
Excuse the rant. Time to visit the heavy bag in the basement.
07-20-2010, 11:21 PM
#26
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07-21-2010, 12:50 PM
#29
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Re. the 1st point I had mentioned ...oil temp thermostat: did the mechanic laugh if it was mentioned? I know that its failure can lead to your symptoms in the 928 - and to overheating of the oil in 993's; however, I do not have a 993 flow diagram to determine if it can play a role in plugging the pump suction.
To have a sudden loss of oil pressure under modest engine demands with the engine full of oil and instrumentation functional generally implies a blockage of pump suction - or loss of pump drive. If the pump is functional, output pressure is determined by bearing clearances ( being on spec), and moderated by relief/bypass valves, etc. So, even if (
) an insert/bearing was spun, one would still have some oil pressure until the engine made horrific noises .... which is apparently not the case.
Excuse the 'thinking out loud' ... but that would have me searching on the suction side as Mike & others have suggested.
We're all wishing for the best ...
To have a sudden loss of oil pressure under modest engine demands with the engine full of oil and instrumentation functional generally implies a blockage of pump suction - or loss of pump drive. If the pump is functional, output pressure is determined by bearing clearances ( being on spec), and moderated by relief/bypass valves, etc. So, even if (
) an insert/bearing was spun, one would still have some oil pressure until the engine made horrific noises .... which is apparently not the case.Excuse the 'thinking out loud' ... but that would have me searching on the suction side as Mike & others have suggested.
We're all wishing for the best ...
07-21-2010, 01:14 PM
#30
Burning Brakes
Thread Starter
Mentioned it to him yesterday - and no, he did not laugh.
Waiting for an update; nothing to report as of this writing. Quad - will know answer to pump/shafts/etc next phone call, I expect.
Maybe I should start researching upgrades to make cost justification easier. Aoy...
Waiting for an update; nothing to report as of this writing. Quad - will know answer to pump/shafts/etc next phone call, I expect.
Maybe I should start researching upgrades to make cost justification easier. Aoy...
