EricPA

Back in July I had an issue during the final session (a Sunday) of the Audi Club School at Mid-Ohio. At the end of the final session the car sounded like a diesel (knocking) as I parked the car in the paddock. The sound was clearly coming from the front of the motor and it sounded a lot like the water pump did when it was going bad last year. Yet the coolant temps looked fine. However, the oil temp was in the 265 range which is the highest I've ever seen in my 20+ track days. The outside temp was in the high 80's - low 90's which is about the hottest track day temp I've seen. (At no point were there any warning lights or error codes.) Lucky for me an Audi mechanic was on hand to hear the car moments after I pulled off the track. We sent the car to his shop on a flatbed so he could determine the cause. Again, the sound was clearly coming from the front of the motor. He gets to the car late on the Monday afternoon and notices the noise is gone. Now a bad water pump would keep making noise even when the car was cold so it most likely was not the problem. Nevertheless, he pulled the front bumper to investigate. The process included listening to the water pump with a stethoscope and looking over the rest of the TB components. All looked and sounded fine. End result? No repairs were made to the car.

Sooo, started thinking the problem was oil related. I was running Motul 300V 5w-40 which I've run without issue at a couple other warm track days. Perhaps it ran a bit thin and the sound was/is lifter related. I went back to track this past Saturday hoping some 10w-40 Amsoil oil might fare better. No luck. At the end of the first session the diesel sound was back. (55 degrees, 250 oil temp) Of course I parked the car for the rest of the day. The sound was gone when I started the car two hours later and the car sounds fine during daily driving.

So am I right to think this is oil related? Any other thoughts?

I already ordered a new oil pump which I will install this weekend.

Sorry for rambling...

visintainer [vis]

you might want to remove the valve covers and make sure the heads were not starving for oil

DocWyte

If that's all you saw without an oil cooler, oil temps aren't an issue.

Silver Streakin'

Motul 300V 5w40, and M1 0w40 and 5w40. Although, the Motul did run cooler, dropped temp faster, but it looked and felt so thin compared to any other oil I've ever seen. I did run it for 5K and had it tested at Blackstone who said it was still good.

a noise is something mechanical that might be starving from oil when the oil thins out, but wouldn't blame the oil itself.

EricPA

I'm replacing it (stocker with 103k miles) this weekend then going to the track again on 10/27. We'll see...

Silver Streakin'

roads and flog it until you see the same temps that you see on the track -- see if it repeats the issue.

DocWyte

Maybe. Could be lifter noise?

P. Bauer

I used to get the dieseling noise with Royal Purple however.

EricVonHa

The problem could be a journal bearing for the crank. It could only exhibit this phenomena once the car is fully heated. If it is, you don't want to find out the hard way.

And, I agree with everyone else that's chiming in on the oil temp issue. It's not that.

EricPA

What would I look for in the analysis to indicate a bad bearing?