Help diagnosing low oil pressure - clogged system?

SummerSmoke

Member
Joined
Apr 22, 2014
Location
Davis, CA
TDI
2002 Jetta
Hi folks,

I've gotten good help here in the past so I was hoping someone would be able to help me out of a bind I got myself into here.

The full story is as follows: The last time I changed my oil on my 2002 jetta, I apparently didn't fasten the oil filler cap down, and consequently when I next drove, it came off. I was oblivious to this until the oil pressure warning light came on while driving. I pulled over and put the cap back on, hoping the low pressure was only caused by the open cap. By the time the light came on again, I was only a few hundred feet from my house so I just pulled into my driveway and shut it off (I later learned this was a bad idea).

The next thing I figured I would try is changing the oil again, just in case that might fix things. This is when I discovered what I believe to be the problem. While the cap was off, oil seems to have splashed up onto the heat shield attached to the hood of the car. It seems to have dissolved away part of it, causing a bunch of fibrous material to fall into the open filler hole. A lot of it is matted up just inside the opening, so I pulled out as much as I could, but I want to try to get as much out as possible before I replace the oil and try to start it again.

Does anyone have a diagram of the oil system? Where would these fibers have ended up once falling into there? Are there any narrow passages that could be clogged? When I removed the filter it looked fairly clean -- so I'm hoping this means that not too much material made its way deeper into the engine workings. The car seems to idle fine without any warning lights so I guess the engine must be getting some oil, just not enough for higher RPMs.

Alternatively, are there any solvents I could safely use inside the oil system that would have a chance of dissolving this stuff? I'm not totally sure what it's made of however...

Truthfully I don't know a whole lot about repairing cars myself, so if I can solve this without having to take apart everything that would be ideal... if that's not possible I might just have to sell it to someone with more expertise.

Any help at all would be greatly appreciated. Thanks.
 

Bran Diezel

Veteran Member
Joined
Jul 13, 2009
Location
Bristol, Va
TDI
On my 5th TDi - 2003 ALH 5spd Wagon
The oil pressure light doesn't come on at idle from what I've been told the PCM doesn't monitor oil pressure then.

You may have a problem with the small o-ring on the tip of the oil filter plastic housing being missing. You can read horror stories here about people leaving it off on the forum here. I would check that, drain the oil and go from there.

You may have to pull the oil pan and check the pickup screen to see if it is clogged, and possibly pull the cam (since low oil pressure starves #1 cam bearing for oil) and pour a gallon or 2 of diesel fuel down through the engine to flush out some gunk.

That last paragraph is a last resort thing, check your o-ring and change the oil and filter and see what happens
 

RacerTodd

Veteran Member
Joined
Jun 28, 2007
Location
Kirkland, WA
TDI
2001 Golf TDI
If you pulled off the valve cover, at the back of the head you'd see a couple of drain holes that allow oil that is pumped up to the cam to drain back into the oil pan. Those holes are, if I remember correctly, about 1" in diameter. I don't think they'd clog up very easily.

What I'd be worried about, if this was my car, is that the material got down into the oil pan and is clogging the inlet of the oil pump. The oil pump has a screen on the inlet that keeps any large chunks of debris from getting into the pump. If enough of the hood liner material got into the pan, it could be blocking the pump inlet.

Hopefully, when you change the oil most of the hood liner material will drain out with the oil. If you still have low oil pressure, I'd be wanting to drop the oil pan, clean it out and re-install it.
 

UhOh

Top Post Dawg
Joined
Dec 24, 2014
Location
PNW
TDI
2000 & 2003 Golf GLS (2005 Mercedes E320 CDI)
Is there any chance that one could get a bore scope up into the pan to see the pick-up?
 

SummerSmoke

Member
Joined
Apr 22, 2014
Location
Davis, CA
TDI
2002 Jetta
The oil pressure light doesn't come on at idle from what I've been told the PCM doesn't monitor oil pressure then.
From the reading I've done I was under the impression that there are two oil pressure switches, one which comes on at extremely low pressure at idle, and another with a higher threshold that activates at higher RPMs. But that could well be wrong.

Sound like the best move for now is to fill it back up and hope the problem is solved then? It just worries me to leave all this stuff floating around in there. At the same time I don't really want to get into pulling the pan off and messing around in there. I'd be worried about correctly re-installing it.

Thanks for your help.
 

[486]

Top Post Dawg
Joined
Mar 1, 2014
Location
MN
TDI
02 golf ALH
make sure you replace the little o-ring on the end of the filter cap, that drains straight to the pan

other than that, clean it up best you can and hope for the best. You could pull off the oil filter adapter relatively easily to clean it, but anything in there's already to your bearings and stuff anyways.

Check your turbocharger for shaft play a few times in the coming few thousand miles, the thrust bearing does not tolerate unfiltered oil at all.
 

vanbcguy

Veteran Member
Joined
Feb 22, 2013
Location
Vancouver, BC
TDI
'93 Passat - AHU mTDI with GTB1756VK
The dual oil pressure switch setup is only found on mk3 (up to 1999) and older cars. VW figured they could save a few bucks and dropped the low pressure switch.
 

RacerTodd

Veteran Member
Joined
Jun 28, 2007
Location
Kirkland, WA
TDI
2001 Golf TDI
From the reading I've done I was under the impression that there are two oil pressure switches, one which comes on at extremely low pressure at idle, and another with a higher threshold that activates at higher RPMs. But that could well be wrong.

Sound like the best move for now is to fill it back up and hope the problem is solved then? It just worries me to leave all this stuff floating around in there. At the same time I don't really want to get into pulling the pan off and messing around in there. I'd be worried about correctly re-installing it.
Mk4 TDIs have one pressure switch. It trips at 11-15psi. The ECU only does the light/buzzer if the switch says pressure is low AND rpms are above 1500.

I'd change the oil, hoping most of the hood liner material goes out with the oil. Double check the small o-ring on the filter.
If low pressure persists, I'd pull the pan and clean out it and the pump pickup. Not a difficult job, but it is a bit fiddly to do. If you're not up to doing it, it shouldn't be too expensive at a shop. I've had my pan off, wouldn't take me an hour to do.
 
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