LS1 Sudden Complete Oil Pressure Loss
 

I just finished my 5.7 LS1 swap into a BMW race car for NASA ST2. When I began I spent a long time looking for the perfect motor. I wanted something clean, low mileage and that i can have the best reliability from. I came across a motor from a 2002 Trans Am with very low mileage. It was stilled owned by the original owner and never modified. He pulled it to do a 525 HP LS3 swap.

Anyway I knew it was a good motor and I didn't want to mess with any of the internals. I did do some work to it however. BTR Trunion upgrade, Push Rods, ASA cam, Moroso baffled oil pan, Melling high pressure stock flow oil pump, new pickup.

So I finally finished the swap and had it on a dyno last week for the tune. All was going well. After we got it to idle the car was being driven in 3rd gear at about 3k rmps and out of no where oil pressure dropped straight to 0. It was never even on the low side before this. Went straight to nothing. We turned the car off right away. We thought it had to be the sensor as this didn't make any sense. Took it out and tested it by blowing compressed air into it and the gauge shot right up. So sensor and gauge are good. Drained the oil and its all metal shavings.

The motor is back out and on a stand. I will be taking it apart tonight. My two guesses are the pressure relief valve on the pump stuck or the pickup somehow come detached.

Any other ideas what could have happened or what to be looking for? Thanks for any suggestions.

https://cimg9.ibsrv.net/gimg/ls1tech...06f6fdef17.jpg

I wonder if the pressure relief valve hung up, bleeding all pressure off. It can happen.

This is my number 1 guess as of right now. How will I be able to check for that?

If the pressure relief valve got stuck, I could see lower oil pressure go low when it returning to idle; but at RPM it should maintain whatever it was. Let us know what you find. We have everything needed to get it back together.

Granted, a different engine, but my mom's 5.0 Mercury Mountaineer. would lose total pressure now and then. Finally lost it for good. The diagnosis was a stuck relief valve. Before, it was sticking and releasing, until it froze for good.

If it was a cam bearing though it wouldn't have had oil pressure for an hour of running time then all the sudden go right to 0. Even a spun cam, main or rod bearing is not enough to have 0 psi of oil pressure. Sure low oil pressure but not 0.

So it had a spun rod bearing but that wouldn't cause no pressure. All cam bearings fine, oil pump and pickup good, pressure relief valve ok.

turns out the canton racing check valve on my oil cooler lines stuck shut.