Low Oil Pressure on Track
 

Today I took my GTS to a track day at Portland International Raceway. I was coming down the front straight about 10 minutes into the first session, when I noticed my oil pressure gauge didn't go above 4. I eased up a little bit and kept chicking the gauge. By the time I got to the back straight, it didn't go above 3. I really eased up on the back straight and took the exit from the track. All the time, the pressure reading was dropping, so that by the time I got into the pits, the oil pressure warning light was on and the digital display was screaming "INSUFFICIENT OIL PRESSURE". I shut down the engine and checked the oil level. It was at the top mark, and the oil looked fine. I couldn't see any leaks underneath.

I let the engine cool down for about an hour. When I restarted the engine, the oil pressure seemed to give normal readings, except it would only go to about 4 1/2 when I revved it to 5K. I decided to bag the track day and to see if I could drive home (about 10 miles). The oil pressure appeared to behave normally, except, again, I couldn't get it above about 4 1/2.

I just finished some major work on the engine, consisting of: a complete intake refresh, replacing all hoses, seals, and sensors; upgraded to the later GTS oil breather system; replaced all cam cover seals and the oil check valve springs and seals; replaced the timing belt tensioner with a Por'kensioner; replaced the timing belt at the same time; replaced the oil pan gasket; changed the oil and filter, using Red Line 20W50.

Before this work, the oil pressure gauge would hit 5 at 5K, but not go any higher. Immediately after I did this work, the pressure gauge would peg at 5K. I took this to mean the oil check valve springs had been weak. I drove the car about 50 miles after completing the work, with no apparent problems.

Any ideas on how to diagnose this? My first thought was the oil pressure sensor, but checking previous posts, it appears unlikely, since the gauge read low, and I got the warning light. My next thought is the oil check valves, since I've read that they can cause low oil pressure. But I can't see what could have gone wrong with them so quickly. Would it be worthwhile to change the oil, in case I got some sort of contamination in the engine?

Thanks,
Tom
'93 GTS, 5 spd., Amazon Green

Oil thermostat?

Sunds plausable, but Redline should be able to handle the heat. Does a Used Oil Analysis test viscosity? May want to check with Blackstone Labs and get the oil tested. Maybe someone poured Amsoil into Redline bottles?:icon107:

+1, although my symptoms were a little different, I could get oil pressure but it was very sluggish and it returned to normal when it cooled down. What do you mean by check valves?

Chris

Tom,

Rather than relying on the analog gauge, have you tried enabling the digital oil pressure readout on the digital dash? This may give you a different and more accurate reading. Just a thought.

My 1st thoughts are oil thermostat...but he changed the "check valve springs"....is this the springs on the oil thermostat or the check valves in the head??

IF the springs and oil thermostat haven't been changed, then that will fix it!!

Another question?? How hot was the GTS running? Redline 20-50 is good oil and should work fine...

I run Amsoil 20-50 racing in mine (similar to Redline) & it works great at the track....never had a single problem & pressure is always good...but I did have the head check valves and oil thermo replaced too?

Have you checked to make sure the oil cooler is not getting blocked. Make sure your cooler holes in the air dam up front are there and unblocked and make sure nothing is flapping down to block the cooler..

good luck..hope you get it sorted by the 12th..

Thanks for all the suggestions. Here some responses:

- I've always heard good things about Redline, and would be kind of surprised if the oil broke down that quickly. However, an oil analysis does sound like a good idea, so I think I'll try that.

- The engine wasn't abnormally hot - well below the red zone. I'll check the circulation around the oil cooler, though. Is it possible for the oil to overheat without the coolant overheating?

- I changed the check valve springs in the head, but didn't touch the thermostat valve. Sounds like this would be a simple first thing to try. But can someone explain how this can cause low oil pressure?

- I didn't know you could display oil pressure with the digital dash. Guess I should read my owner's manual.

- Tom, my big worry is that I don't get this resolved before Spokane, and I drive all the way out there only to have it happen again. Or, I wound up stuck in Spokane with a blown engine.

Tom

Sounds like the symptoms of oil breakdown to me too, but again, Redline is decent stuff and 20-50W is not a light oil, in which case it can only be the oil not being cooled and it running very very hot.

for a quick test start the car get it up to temp and pull the dipstick let the hot oil drip onto a black colored piece of cardboard or plastic. Look at the oil in the sunlight see if you find any small metallic particles if so then a bearing is starting to go bad. Probably the 2/6 rods. If there are no metallics in the oil then a oil change might be the cure But check the thermo springs first

Yes, you can get your engine oil REALLY hot without overheating the cooling system. The oil temp on my A6 goes up 100F over normal operating on the track, while the coolant temp stays exactly the same.

Tom-
You won't find how to activate the digital dash in the owner's manual. You need to look at the digital dash suplement in Jim Morehouse's CD's. It's in CD1 under "other." If you need, PM me your email address and I can probably email it to you.

Might not be a bad idea to change the oil filter & cut open the old one to have a look see.

Yep, we get to near 280F on extremely hot days at the races, while water stays near normal. normal oil tems on the freeway, are near 180F.

mk

Tom
Since you are changing the oil change the thermo springs too...here is an excellent write up by Tony on how to do it

http://members.rennlist.com/v1uhoh/oilp.htm

The springs are cheap...only a few bucks & its not hard with the correct stubby wrench (27 & 32mm I think)....

A blocked oil cooler is also possible.....more likely really since when the thermo springs fail it tends to cause a loss of oil pressure at low rpms when the engine is hot.....