oil light coming on at random times

[casrhino]

I have been using the same mechanic for years. He is usualy very good at what he does but he has run into a problem. The oil light on my 02 turbo will come on at random times and he cant figure out the problem. The first time it came on i took the car to him and he replaced on of the tubes running to the turbo. Said it was a vacume tube and it had split causing a pressure loss. Car was fine for about two months when the light came back on. Took it back said the oil was a little low but everything looked fine. LIGHT CAME BACK NEXT DAY. He said the pressure is fine and he doesnt know whats wrong. Now looking for a new mechanic and some advise what might be wrong.

[MyOtherRidesAVette]

If the pressure is fine, determined with the proper equipment, then there is a good pssibility it is the oil pressure sensor. This seems rather basic. That your "good" mechanic, and one that you have been comfortable with, can't find the source of a problem, is not reason enough to "fire" him. Call and discuss the possibility of it being the sensor with him. May simply be a case of not being able to see the forest for the trees!

M.

[casrhino]

Thanks, He said he replaced the sensor on the first visit but I suppose it is possable that the sensor could have been faulty. I was also told about a screen that could be clogged that could affect oil pressure.Any ideas?

[MyOtherRidesAVette]

Yes, the screen on the oil pump pick-up. That could be the cause, contaminents building and then being "washed" back off by movement of the vehicle. I didn't think about that, but that coud be entirely possible. Seems I remember reading somewhere also about an odd positioning of this on some engines, but then it could have been something else all together.

What oil are you using (Brand, flavor, and grade) and when was your last oil change. There are oil brands that contain a high parafin base that will cause sludging. One of the reasons I prefer Mobil 1, the only major brand, true Class 1, full synthetic (no parafin base). If this has started occuring, or is occuring more since then, it would be a good idea to change the oil and look carefully through the drained oil (pour it through a fine screen type filter).

M.

[billymade]

Interesting post here: mentions sludge issues, low pressure from clogged internals (specifically the filter on the oil pickup tube); food for thought anyway.... possiblities....STOP LOW OIL PRESSURE 1.8T - Topix Seems; pull oil pan clean sludge; clean or replace pickup tube, replace oil pump if needed and this fixes the problem, check your lower end bearings while your in there to see if the low oil pressure caused wear.
Checking the oil pressure at the sensor would be a good idea; that way you can tell what is really going on; eliminate the sensor as a variable... sounds like a symptom of a greater internal problem. My 00' had this problem and the dealer ended up changing the oil pump.. problem fixed.

Some good pics of the pickup tube and problems people have with the screen clogged!
http://www.audizine.com/forum/showth...by-My-Teardown

[psaboic]

After you sort it out, try installing a proper oil pressure gauge in tandem with the stock oil light. I did that and a couple years ago when my oil light came on, instead of freaking, I was able to look at my gauge and see I still had 40 psi of pressure. Needless to say, a new oil pressure sender fixed the damn "idiot" light issue.

[MyOtherRidesAVette]

Agreed, I'm all about gauges. However, just to have them, unless they are scanned, almost continually (having owned many boats, starting at a very young age, I learned to do this as a matter of course), they are pretty much worthless. At least a warning light, esp when coupled with an audible signal, is much better for most people.

M.

[Smileybug]

Definitley need to know what kind of oil you are using. Conventional or synth is an important answer. 1.8T engines NEED synth. Conventional can cause sludging, which is nasty to deal with.

[casrhino]

I got the car back from the new mechanic today. Oil pump needed to be replaced. Pressure was dropping when rmps reached 2500. Drove car all day and everything is fine now.

[billymade]

Glad you got it handled! Interesting, that's exactly what had to be done on mine! I think many times; everyone assumes it a problem with a sending unit or sensor... best to get to the heart of the matter! The car was telling you what was wrong! Glad you caught it sooner then later; what did the mechanic say about the pickup tube or any bearing or head problems? I guess you got it early... lucky!

[MyOtherRidesAVette]

Originally Posted by casrhino

I got the car back from the new mechanic today. Oil pump needed to be replaced. Pressure was dropping when rmps reached 2500. Drove car all day and everything is fine now.

Oil pumps do weaken with age, and this would be the result, drop in pressure under load. ANOTHER argument for the use of 0w or 5w synthetic, as opposed to 10w conventional oil as some have suggested is just fine (faster, easier flow on cold start and better protection with reduced flow).

Glad you got to the "heart" of the problem and got it taken care of. A lot of people would have ignored a sporatic ("at random times" as you termed it) warning light until it was illuminated all the time, and by then you probably would have done damge to the engine and/or turbo. Seems it really wasn't so sporatic, but more related to the specific accelerated "pulse" of the engine.

M.

[psaboic]

[QUOTE=billymade; I think many times; everyone assumes it a problem with a sending unit or sensor... best to get to the heart of the matter! [/QUOTE]

I disagree. Yes, many people "assume" the sender is bad, but for good reason. The sender, which is an electrical part, has a higher failure rate then an oil pump. I have been driving for over 30 years and have only seen one pump go bad, but many electrical senders. Either way, I'm glad the OP got it all sorted out.

Now, go put a gauge on it <grin>