Whitey13

After lots of searching, I couldn't find the answer so here goes...

Oil pressure on cold start up is 35 psi give or take a few pounds.

Once it's warmed up at idle, it's between 10 and 20 psi.

Crusing, it's about 20 to 23 psi.

WOT, it never goes above 30 psi. I mean when it's bouncing off the rev limiter, it doesn't change. Power is there and everything sounds just fine. Possible oil pressure sending unit problem? Or much worse?

shoebox

Sending unit problem possible. Or your bearings or pump are not so healthy.

Whitey13

Thanks shoebox. Is there any kind of damage being done running at high rpm's without the oil pressure keeping up?

shoebox

Low oil pressure and high RPM is a recipe for bearing damage.

'94 Bad A Z28

Umm... P.S. your A4 car should NEVER bounce off the rev limiter.

Whitey13

And why is that?

klrz28

remove oil cooler, 9 times out 10 its plugged

shoebox

Did I miss where he says he has one?

'94 Bad A Z28

Because if it does not shift when it is supposed to, unless you hold the gears manually and let it bounce of the limiter for some reason, it is on it's way to needing a rebuild or already needing one.

Whitey13

Oh, I thought you meant it was bad for it or something... But no, it shifts when it's supposed to, I just meant when I go through the gears and bring it up to the top of each gear.

Whitey13

Are oil coolers a factory option? How do I know if I have one?

shoebox

Your car would have RPO KC4 on the sticker in the glovebox and you would see hoses going from the radiator and the water pump toward a sandwiched block between the oil filter and the engine block.

Whitey13

That's some good info, I appreciate it. I just got back from a cruise and I noticed at a stop sign my oil pressure needle was bouncing around. It was steady at 15 psi then it instantly went to 20 then back to 15 and kept doing that then for a couple seconds before it went back to 15. The car was running and idling just fine though. It's starting to sound like the sending unit is going...

Guest47904

Just a little confusion????? Clearly from Shoe's diagram, the coolant flows to the oil cooler NOT oil to the radiator. So if that's the case, how could a plugged oil cooler create problems with oil pressure???? Would it be just from temperature build up? I wouldn't think so.

Maybe one easy test would be to put a thicker oil in and see what the pressure does. According to accepted standards, for every 1000 rpms there should be an increase of 10 PSI.

shoebox

No, the cooler gets clogged from particles within the oil only part of the cooler.