I will mail the person that fixes this issue money. No joke. I'm stumped

Ok so bought a used 2002 Audi A4 1.8t... Day one the low oil pressure light comes on, previous owner swears it never came on for him... take it to the dealer the next day and have the pan dropped, bearings inspected, and pickup tube cleaned.... Did a 4 stage oil flush and fill it up. Pressure tested very well. Oil light comes on less often but still comes on. Only after a long drive at about 1600 rpm.. And only for a second.. I've read about this happening a million times on forums and most people say to clean pickup tube but I've already done this so I replace the oil pressure sensor.. Light still comes on but after long drive, low rpm.... . So back to another shop. The shop does pressure test hot and cold.. Good pressure... They pull valve covers and inspect cam shaft journals.... Engine looks very clean and in good working order, correct clearance on critical parts. So they replace the pressure sensor yet again and the oil light goes off for about 2 weeks.. Now the last 2 days it flashes after long drive, low rpm, VERY intermittent... And it seems to happen after I take a turn.... this isn't 100% verified but its a hunch. Ok so what do I do? I've had bottom end and top end inspected.... Pickup tube cleaned, 2 pressure sensors replaced, 3 or 4 pressure tests (all have been good).... I'm stumped what to do next.


A side note- my coolant temp and fuel level dials seem to 'misbehave' reading about 1/4 mark high every now and then... Dunno if this has anything to do with it but maybe I've got electrical cluster problem that's linked to oil pressure light? I doubt it because it always happens under the same scenario so it seems too predictable for it to be an electrical problem...

Oh, of course oil level is perfect... My next plan is to install an aftermarket oil pressure gauge this Friday so that I can have constant tracking of pressure.

What's next guys? Both shops say the oil pump is healthy... Engine isn't over worn.. No sludge... Cleaned pick up tube... Synthetic oil...

I'm at such a loss that if you fix this problem ill mail you some cash for your help. 20 or 50.... Depending how generous I'm feeling that day. But in order to receive $ your suggestion must solve problem and survive a trial period. Thanks guys!

PLEASE HELP!!!

 

I know this is a stretch, but do you have the windage tray in the oil pan? #26 in the first picture? This could be a reason why corners create this condition. I would think it would have to be a fairly high speed corner to make the oil sway away from the pickup tube if the level was full. The other thing I was looking for in the drawings is a check valve in the head or block, but I didn't see one like some other engines have. I would look at the oil filter mount to block component. Inside this is the oil pressure relief valve. Through the flushing that you've already done it's possible that the check valve #3 in the second picture gets a small piece of debris to stop it from moving in its bore. That machined bore to piston is a very tight clearance and anything that could impede it's movement forward to a relaxed spring pressure point would result in lower oil pressure since that valve isn't in the correct position to maintain proper oil pressure. Interesting issue on the electrical side note you mentioned. Maybe somebody else has had issues with a cluster creating problems.
The key is that oil pressure gauge you are going to mount. If you see oil pressure that fluctuates in both directions high and low I'd bet on the oil filter mount. We do sell on average 1-3 per year for the last 3 years. But I don't know the common reason for replacement.

 

Thanks for your reply... yes that windage tray is in the pan... Interesting that you sell those. So the part your talking about is #1 in the second drawing? if I removed bolt #6 should i be able to see any debris? can I remove that bolt with full oil? Maybe I will do that on saturday to eliminate that possibility. The turning part is really weird to me as well because its a pretty slow turn. parking lot turn. Im going to be installing the gauge on saturday morning and see what that tells me. What oil pressure numbers should I expect to see? anybody else have more ideas? this weekend I will also replace oil filter just in case my flush stirred up a bunch of stuff. More ideas welcome.

 

another question about all of this that the two shops I went to couldn't answer. and my owners manual wasn't much help either. The light I am getting is an oil can with the word 'oil' written underneath it. It beeps 3 times and flashes. thats it.. No stop sign like one dealer said it should... not 'oil pressure' like the other shop suggested. Is this normal? whats the 'low oil pressure' light supposed to look like? ive googled and dug through my owners manual to not much luck

 

Oil level sensor. Not pressure.

/already spending the moneys

 

Yes I'm talking about #1 in the second drawing, that as the assembly because the plunger and spring 3 and 4 aren't available seperately. You won't lose much oil at all taking those out for inspection, you may lose a few drops. On the windage tray I may have misled you, I was talking about the sales history on #1 from the second drawing, I don't sell many windage trays.

 

arapey are you sure? I discussed that possibility with the dealer and he said that for low oil I would get a oil can with waves underneath that says 'min'... this is also what my owners manual says I will see. There is also another warning light that has the oil can and says 'sensor' when the sensor is going bad. I am not getting either of these

 

also the flashing red oil can is red. ive heard that a flashing yellow can means something different? can anybody verify this? Im colorblind but pretty sure its red that im seeing... will try to verify with another person in next few days

 

yellow means "caution, something needs your attention". if you see the yellow oil light (can with "min") it means there is a "caution" condition. In the case of our cars it is check the oil level.

red means "stop your engine, there is a problem and something may get f'ed up". if you see the red oil can it means oil pressure is critically low either due to being empty or some other condition that is preventing the oil from flowing through the engine properly

tl;dr: yellow=hey check this when you get a chance. red=something is very wrong

as far as the specific problem with your car, I have nothing further to offer than what you have been told by the shops that you've had look at it, and what they guys above have suggested.

 

Of course I'm just guessing but honestly it's a mechanically driven device... either it works or not. Unless you have a big chunk of garbage floating around in your oil pan that intermittently clogs your pump it reasonable to think there's not a mechanical problem. If there were they should have seen something when they pulled the pan and did an inspection.

Your idea to get an aftermarket oil pressure guage will put your mind to rest. I suspect you won't find a problem and it's either electrical possibly caused by heating or grounding.

Just my 2 cents.