'98 A4 2.8 - Oil light

Last week my son bought an A4 Quattro with 109,000 miles on it. The engine sounds good & it drives fine. [There is a whine from the rearend, but another Audi owner told him that is normal. . . ? It
was unlicensed so driving any distance before we bought it wasn't possible. ]
At about 180 degrees [oil temp] the oil light comes on. It goes off and on randomly after a few minutes. Somtimes it will stay on/off for a couple minutes, sometimes seconds. The water and oil temp stay steady, so I'm guessing that the light is lying and the lubrication is still working.
I've tried to see a pattern on what makes the light go on and off but accelleration, de-celleration, up hill, or down hill make no difference. It comes on regularly at 180 degrees-- but then it is completely random.
The car had been sitting for 4-5 months & still has the same oil in it. Tomorrow that gets changed.
It seems to be going on and off more frequently the more he drives it, but it still comes on regularly just as the oil reaches about 180 degrees.
I'm thinking that it is probably a clogged screen that is slowly unclogging itself-- or a sticky sending unit. Any other thoughts-- or a thought on how major a job dropping the pan is on this thing?
Thanks- Jim [This is my son's first car & though I tried to talk him out of it, the Audi is growing on me fast--- The sound of the doors shutting is a simple pleasure by itself.]
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Rear wheel bearings, common that they go around 100k miles, whinning from the rear end is not normal :) it will just get louder and louder

Oil pan is pretty easy to drop I would suggest changing the oil and filter and maybe the problem is a sensor failure, check www.audiworld.com and have a browse and search through the forums, you will find plenty of stuff in there

Hehe you will soon be buying one yourself :)
good luck
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Ronny wrote:

Yes. Second that.

That would be my guess too.
Any other thoughts--

This is a link directly to the B5 / B6 A4 Audiworld FAQ thread: http://forums.audiworld.com/a4/msgs/2299748.phtml
You will find a section for oil related issues.
After market filters are a bad choice. Get one from you local dealer or be sure to get a Mahle brand which is equivalent to OEM.
You will also find a recomedation on oil viscosity and brand. Mobile One (synthetic) is a good choice.
TonyJ 98.5 1.8TQM APR Son's car: 98 A4 2.8Q Tip
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First off-- Thanks to Tony, Ronny, Pete, Mike & Daytripper for your thoughts and comments.
My mechanic has had a bad couple weeks-- and I made the mistake of saying-- "We're in no rush." Well, I wasn't-- but I forgot this my son's toy & I was just dropping it off while he was working to pay for it.<g>
Changed oil, filter & sensor. It delayed the light for a bit the first day, but then it responded just as before. [light on when engine reaches temp-- then on and off randomly, no change regardless of rpms.]
So last night he put his digital oil pressure guage on it [in the same hole where the sensor was] and told us to take it for a ride.
While sitting at the garage, cold idle was 30+ psi, pressure at 2000rpm was about 40.
Once warm, the pressure at idle drops to 6psi, sitting at 2000rpm it hovers in the low 20s.
Out on the highway, holding steady at 2000rpm the pressure went from 20-27 for the first 5-6 miles, then evened off a bit to 22-25. It stayed there for 20 minutes or so-- and went back to 6psi at idle on the offramp.
My mechanic [not an Audi man, but a guy I've trusted for 20 years with my cars] can't find anything but the 29psi at 2000rpm for oil pressure specs. I've ordered the Bently manual but if someone has some more datapoints, I'd appreciate it. [What pressure should trigger the light? How bad does the oil pressure sound?]
Mechanic is leary of this and thinks it sounds more like a "tired motor" than an oil pump/clogged screen problem. Any thoughts?
-snip-

Thanks for that link-- lots of good reading. [But I didn't see anything on 'what your oil pressure *should* be'. If you think it's there I'll go back and try a little harder.]

We got the Audi filter-- but I talked to the other mechanic- who actually changed the oil, and he used 10w-30 -- he's replacing that with 10w-40 today.

I think I'll run the 10w-40 [Pennzoil?]- for a week or so, let it pick up whatever gunk it can- then replace it with the Mobil One.
Thanks again to all-- Jim
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Both the Bentley manual and Haynes give only the 29 psi (or 2 bar) at 2000 RPM minimum spec for oil pressure when oil is at 80C on the 30V 2.8.
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-snip-

Thanks Ian. I wonder why they ignore idle pressure on this engine?
And I guess my question for the dealer who will be topping off the transmission fluid next week will be "Is 25psi cause for concern?"
Jim
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wrote:

2000
Not sure but they give idle specs in the Bentley manual for the 1.8 turbo four of 14.5 to 50.75 for types AEB and ATW and 19 psi for type AWM. This may be because of the turbo. Haynes lists an idle pressure for the older SOHC V6 of between 15 and 36 psi and pressure of between 44 and 73 psi at 3000 rpm but no spec for 2000 rpm for that engine.

The pressure sounds marginal. I'd be inclined to try an xW-50 synthetic oil to see if that brings up the pressure enough to meet spec or at least keep the light from coming on. A new oil pump might be an option but if the wear is more generalized, then it might not help enough. Good luck!

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The sound of the doors shutting is a simple pleasure by itself.]
Oh yes! Not many cars that'll do that - especially after those miles - - - - -
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"Jim Elbrecht" wrote

I'm thinking that by 180F, the oil thins enough for the sensor to register an oil pressure which is too low. What viscosity oil are you using? It could be a sign of a failing oil pump, me thinks.
Cheers,
Pete
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Ever seen an oil pump? They are unbelievably simple and unlikely to fail before an oil pressure sensor - which is almost certainly got clogged the first time the car was heated up after storage.
I'd change the oil, filter and pressure sensor and call it a day...
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"daytripper" wrote

Actually, oil pumps aren't that unlikely to fail under certain conditions - sludged up 1.8T engines come to mind. Depending on what maintenance and what oil was used on that 2.8, it's a possibility as well.

Sure. I'd start with that and see what happens. Then, worry about the more expensive stuff.
Cheers,
Pete
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What I said was:
'Ever seen an oil pump? They are unbelievably simple and unlikely to fail before a pressure sensor."
In the future, please refrain from altering my posts to make your point...
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"daytripper" wrote

How did my snipping a part of your post alter the sense of what you said and how I responded? You're saying that a pressure sensor will likely fail before an oil pump will. And I'm saying that an oil pump may fail and the pressure sensor is just letting you know that. Here. Two different ideas. I don't have to agree with yours, and you don't have to agree with mine.
Cheers,
Pete
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