WTF is going on with my car?
My oil filter is remoted and I have a large oil cooler. There are 15psi OP switches near the pump at and the galley that are separated by a checkvalve and Accusump. Therefore they read different information. There is an OP sensor at the galley to provide a conventional OP reading and another at the Accusump to indicate when the sump is discharging.
Finally, there is a sensor near the pump that is connected to the Traqmate. This log if the oil pump sucked air. It isn’t a record of OP at the galley tho because the galley OP is supported by the sump.
I lost OP at VIR a couple weeks ago on day 3 of the weekend. It was day 3 that I started pushing harder, day one and two had a lot of rain. When my very bright OP light went on I immed put the car in neutral and rolled off into the grass. A moment later I restarted the car to see what would happen, and OP remained 0.
The next day, at home, my OP was fine.
At Roebling today after a half dozen laps both pump and galley OP lights went on. Both galley and sump’s OP gauges said 0 I put the car in neutral and started coasting with the motor still on. I rev’ed the engine a couple times in neutral to 2500 or so to see what would happen. Still 0 oil pressure.
In the pits I started the car again, still no OP. 20min elapsed and I started the car and my OP was fine.
Since the situation was so strange I started trying oddball things to see if I could affect the symptoms. In order to see if it could be temp or visc dependent, I idled the car for a while and got the oil temp up to about 190deg. No affect…OP was fine. Next I changed my Bosch oil filter just in case it had failed in some unlikely way that prevented it’s bypass from working.
Then I went back out on the track. I was watching the two OP gauges like a hawk. The gauge on the sump was the key because it would tell me that OP loss was forcing it to dump oil into the engine. On lap 6, in the exact same place…turn 6 my OP lights flashed on, but then went off. As the lights went off I watched both OP gauges climb up from ~0. Holy shit.
On the next lap, in the middle of turn 6 again, my lights flashed on. But this time my OP didn’t start climbing up. It stayed at 0. I popped it in neutral, rev’d the motor up a couple times to see if OP climbed (it didn’t), and then coasted into the pits.
Back in the pits I started it again and still no OP. Then I removed the oil pump drive shaft port, which took me prob 15min and ran the oil pump with an impact wrench. Oil pumped fine. Then I put the port plug back on and started the motor…OP was fine. So each time the solution was to let the car sit for 20min.
This is figure-outable. Everything is. It doesn’t happen on straights, it happens on turns. It can’t be a coincidence that it happened in turn 6 both times at Roebling.
Since I’m logging OP I have interesting curves to study. I can see OP dropping in turn 3 and 5. I wasn’t going very hard, but OP was dropping to high 20’s in turn 3. The spare does not have a crankscraper. Watching the OP gauge on the Accusump I could see the sump largely empty itself trying to maintain pressure in 5. Then when the sump needed to get replenished after turn 5, oil quit flowing and it had almost nothing to give.
I gave ChuckB a call about 1/2 way thru the day to see what ideas he might have. The situation is so odd that it’s hard to come up with a theory that fits the symptoms. The only theory we have right now is that there’s something in the oil pan that is able to block the oil pump’s pickup holes when conditions are just right.
I’m going to remove the oil pan this weekend and see what’s up. I’m worried that I’ll find nothing.
