Got a 98 Trans Am and it hold oil pressure great when normal driving but when I go WOT for more than 5 sec oil pressure drops to zero and lifter starts rattling on left side of engine.. After turning the car off for a min or so it will regain oil pressure back to normal and all is fine.

Like I said above if you are just normal driving oil pressure is fine, would bad Lifter (collapsing Lifter) be a problem? Car has 144,000 miles runs 5-30w oil. I haven't owned it long at all, previous owner said new oil pump was installed also, but it was probably a stock one and could it have maybe been put in incorrectly? The car is bone stock at the moment from front to back, when looking for a car I was just looking for a clean slate to start with


Thanks!

 

It occurs to me that the lifter noise is probably due to loss of oil pressure and not the cause of it. Are you sure you are not low on oil? You may have an oil pump, pickup, pan problem still.. I think it is possible the pump is starving under acceleration(oil rushes to back of pan and pickup not getting it somehow?) and causing this issue. What if you go WOT and don't let the RPMs Get above say 3K? Is it any different then? (like is this WOT or acceleration or RPM issue or all of the above?)

Just food for thought.

Good luck with your issue.

 

Thanks for reply, I had just changed the oil and it was spot on. They I went to the Track about 2-3 hours later. It only does it under hard hard acceleration, driving around town and getting on it a little oil pressure does nothing and is fine. But the moment you got WOT for any length of time oil pressure pegs zero. Given I have only done this once because I am scared of hurting the engine under these circumstances.

After much thought, I think I agree with you. I think it maybe a pickup/pan/pump problem. See bad thing is I don't know what the guy replaced, he could have just put a pump in the car and not anything else. I will probably just replace oil pump, pickup, ect again just to be sure and this time put in a GMPP/SDPC Blueprinted & Ported LS Oil Pump that way I know its done correct. As we know you cant trust anyone these days

 

Sounds like a good plan for piece of mind. There is also some sort of bypass in the LS motors that would be worth researching I think.

Good luck!

 

I know my 2006 ls2 has an internal bypass in the pan. I am pretty sure it just bypasses back to the sump.