jimbo1111

Has anybody experienced a sudden loss of oil pressure? It's kind of boggling me. The only thing I can think of is that the pick up tube may have bin damaged after I slightly bottomed out over a steep driveway. Oil pump looks fine. I removed the oil filter and replaced it and the pressure restored. I thought everything was fine. Than after shutting off the car and letting it cool down. On a restart I had no pressure again. I know it isn't the sending unit because the valve train is making a racket. I may need to pull the pan off and have a look. Any ideas?

fortysixandtwo

Assuming the gauge is correct, first step would be to verify that you have oil. Second is that the crank snout bolt is torqued to spec. If it has loosened, the oil pump may not be spinning.
A break in the pick up tube is possible, but not likely caused by bottoming out. The oil pan is cast aluminum, and if it deflected enough to damage the pickup tube, its likely the pan would have cracked also.
The next thing I would do is remove the oil pressure relief valve and see if the plunger is stuck open or not sliding freely. It can be removed with the engine in place, and since you will not be removing the whole housing from the block, there will be no need for using the alignment tool.

Beyond that, you start taking the engine apart.

Willard Bridgham 3

+1 oil pressure relief valve.

jimbo1111

I'm starting to think that I have a dying A/C compress bearing and its weighing on the Crank Bolt causing the oil pump to lose rotation. Anybody know the serpentine belt size to delete the A/C off hand?

jimbo1111

Update: after pulling the pan replacing rod bearings, inspecting the oil pickup, fresh o rings on the pickup and oil-cooler. It turns out the oil pump was starting to fail. Caught it in time and saved the motor. Thank God. The oil pump was my last resort. Because you rarely hear of oil pumps failing so the mind gravitates to different areas. Keep in mind I had just come off the track running 7k rpm. The pump decided to fail just as I drove it into the garage. For those looking to solve that dreaded #2 rod bearing issues. Please don't overlook a failing oil pump as the culprit.

fortysixandtwo

Thanks for the follow up. Do you still have the old pump? Do you mind posting up some pictures of the worn out pump? It may serve as a reference to those rebuilding their engines.

reno808

Wow good catch

Ski

Yeah I'd be interested in seeing some pics if you break it down. Sudden loss, I too was thinking pick up or the galley plug under #1 cylinder. Then you said it came back.

jimbo1111

Yea, Don't know if I'll have time to break it down. I suspect one of two reasons for the problem. Cavitation issues with the pump running sustained hi rpm or a break in the locktite seal to the block. I did bottom the car out a bit on a moderate slope. That could also create some kind of pressure or suction loss. Either way I'm pleased the problem was solved without catastrophic loss.

xsboost90

hm- have you ever seen the inside of one of these pumps? not much to fail. Ive had this at the track and it was the three piece oprv stuck wide open. PUlled it and reinstalled it and it was fine. Replaced it with a one piece and never looked back. Interested to see HOW a pump failed.

txhokie4life

I've had one fail in my chumpcar -- and I think I lost another in my 951
(lost OP) and spun #2 (just barely)

I haven't pulled the pump yet. Caveat -- in both cases these were engines which had
suffered prior failures --

the chump car oil pump looked to have some signs of previous debris and
I know my 951 suffered a catostrophic loss from the PO.

While I'm rebuilding -- can anyone give me specs for the pick-up tube skirt?

Mike

zerMATT951

At what point do most people consider replacing the oil pump? Is there any specific wear items to look for when it's apart?

I ask because I've got my freshly-rebuilt short block sitting in the garage waiting to be mounted on my engine stand to finish assembly. I spun a #2 bearing, and I suspect it was because of a stuck 3-piece OPRV, but I am not certain. When I pulled the oil filter housing off, the OPRV plunger didn't come out easily. I'm not sure if I caused a mis-alignment when removing it, or if it was stuck by itself.

Anyway, itt's got a good condition freshly-polished crank in there now with all new bearings, rings, balanced, etc... and I hope that I don't repeat this problem again. I have a 1-piece OPRV ready to be installed now too.

txhokie4life

I'll be checking my oprv as well :-)

When we pulled our Oil Pump on the chumps car, we could see signs of debris in the pump.

I haven't finished pulling 951 engine out -- that will happen tomorrow.

Mike