stiness101 Posted October 28, 2010 Share Posted October 28, 2010 Hey guys, So when the engine revs out to 6-7k, the oil pressure drops. It does not go to zero, but my guess it it loses about 10-15psi. I've replaced the oil pressure sensor with the same results. I was wondering if maybe there was some sort of cavitation issue with the oil pump failing at high RPM. Oil level is full so I dont believe its running out of oil. A little bit of history behind the motor - it hadn't been run in years before I installed it. It is somewhat built L28, flat top pistons, e31 head, bored out to 2.9l. I am running 10-30w castrol syntec now but will be switching to amsoil next change. When i installed the engine i pulled the pan off and made sure there was no issue with the pickup and everything looked fine. I plan to hook up an external pressure gauge besides the stock one just to check and make sure its not the gauge but just wanted to see if anyone else has had this issue? Thanks. Quote Link to comment Share on other sites More sharing options...
johnc Posted October 28, 2010 Share Posted October 28, 2010 Hey guys, So when the engine revs out to 6-7k, the oil pressure drops. It does not go to zero, but my guess it it loses about 10-15psi. I've replaced the oil pressure sensor with the same results. I was wondering if maybe there was some sort of cavitation issue with the oil pump failing at high RPM. Oil level is full so I dont believe its running out of oil. A little bit of history behind the motor - it hadn't been run in years before I installed it. It is somewhat built L28, flat top pistons, e31 head, bored out to 2.9l. I am running 10-30w castrol syntec now but will be switching to amsoil next change. When i installed the engine i pulled the pan off and made sure there was no issue with the pickup and everything looked fine. I plan to hook up an external pressure gauge besides the stock one just to check and make sure its not the gauge but just wanted to see if anyone else has had this issue? Thanks. Check the pickup to be sure it does not have an air leak somewhere and make sure the pickup is 1/2" off the bottom of the pan and isn't sucking down into the pan. Quote Link to comment Share on other sites More sharing options...
Tony D Posted October 29, 2010 Share Posted October 29, 2010 The important thing to ask is 'how long'? Is this happening in a 1/4 mile race? At the end of a straight? Free revving? The biggest reason for a 7qt oil pan is the fact that the stock pan does not contain enough oil for the engine to actually pump it all to the top end and have time to drain back to the sump to be pumped up again. You may simply be sucking oil out of the pan and throwing it to the top of the engine where it resides long enough that you are sucking air simply because drainback can not occur fast enough. "Accusump is your friend!" Quote Link to comment Share on other sites More sharing options...
stiness101 Posted October 29, 2010 Author Share Posted October 29, 2010 Hey Guys, When I had the pan off, i checked the pickup and the screen was not smashed and everything was tight. there wasn't any holes in the welds or brazing either. For length, it is really if I'm just accelerating hard through about 3 gears. I guess it could make sense since it seems to drop in say, the end of 2nd gear going into third that it could be possibly sucking up all the oil. I could try overfilling it a little bit, about how much can i go before it causes any windage issues? An accusump would be nice but I dunno, i don't really want to put it on the car since its just a street car. Quote Link to comment Share on other sites More sharing options...
Tony D Posted October 31, 2010 Share Posted October 31, 2010 An accusump would be nice but I dunno, i don't really want to put it on the car since its just a street car. Street Cars through their connecting rod through the block wall at #5 far more often than race-prepped engines do! Revving to the top of the rpm range is not considered 'normal street use'... Sounds like something may be wrong, as if you are only running to 6500 the oil pressure should not be fluctuating at that point (top of second) stock stuff should be good there. I was thinking a little higher than that, and maybe in a specific direction corner. Maybe oil pump is weak, relief valve spring is weak, since this is an Electric Gauge could be simple high-rpm vibration making a bad intermittent contact on the sender sending a 'false signal'--mechanical gauge might help isolate it better to see if it's really a problem. Quote Link to comment Share on other sites More sharing options...
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