99 Camaro 82k miles stock bottom end LS1. Lets start with Ive never had this happen to me prior to swapping out my clutch. Ive tested this a few times now and it happens the same way every time. Cold start the car starts up and has great oil pressure 60~. I go for a short drive 5~ mins 1-2 miles keeping RPMs around 2500 and under just shifting and staying in a high gear. Once warm pressure will stay around 40~ which has been the cars norm for the last 7 years Ive owned it. Now I go for another short drive 1-2 miles and once I give it some revs lets say 3500 - 4000. Oil pressure will drop off pretty fast to the point where it will Idle around 25-30. Then I get a terrible lifter tick and car starts to run like ***. So I stop let it idle for 2-3 mins and sound goes away pressure returns to around 30~ and the car runs like it normally does. I rev it in neutral and I get absolutely no fluctuation in oil pressure. Pressure will stay at 30~ and then lifter tick will come back and the car will start to run like *** again. Basically it runs good and makes good oil pressure at idle. Once I give it some RPM pressure just falls off and acts like there's a blockage of some sort. I did the cam swap last year and has been great since no issues there. Other than that I haven't touched the engine since besides 1 oil change. I change the oil every 1500-2000 miles for the last 7 years Ive owned it. Oil is always very clean. I run mobil 1 syn 5-30.

Ive done this now 3 times and it re occurs the exact same way every time.

What Ive done so far:
I changed the oil and filter. Hasn't made a difference

Now I just installed a new LS7 clutch and while I was there I replaced the rear main seal. I replaced the entire rear cover with no bolts, gaskets, hardware. Put it all back together and went for the first test drive with the new clutch and everything was going great until... this.

Im wondering if this could be caused by the new rear main cover I installed. I know there is oil passage that runs through it just like the front timing cover. Maybe its obstructing the oil passage? This has never happened before until I did all of this recently. Very weird.

Please help!

 

You shouldn't have had to remove the cover to replace the rear main seal and I wouldn't think that's the issue but then again if the problem didn't start until you did this then it's safe to assume that there's an issue with the install and it's possible that oil is leaking past the seal for the lifter galley.

 

I was thinking the same thing. That’s why I was looking for any other ideas before I pull the trans again

 

Did you check the barbell? That's under the rear cover, and you just worked on that so... Also, there's an oil plug in the block near the oil filter (as I recall), that seals the lower end of that oil passage in the cover, it's possible to take out that plug and run a wire brush up through the passage to clean it out.

 

I didn’t remove the barbell but I did take a glance at it and it looked fine from what I could see. I was thinking there could be an obstruction somewhere but how.