40,000 on rebuild. Cover from underdog I've got 70psi cold, but hot at idle I've got maybe 5. It used to be quite a bit higher. It's an already used factory timing cover that underdog refreshed for me, but maybe it's finally worn itself out? This engine overheated pretty badly a while ago, maybe the cover warped? What say you guys?
It’s normal for ANY engine to have higher oil pressure cold than hot. If yours had higher than 5 lbs hot idle before the overheating something changed obviously. Have you changed the oil since the overheating?
A substantial drop is an indication that something is hurt. I would inspect the oil pump first and hope you find something, but I'd bet your looking at torched rod bearings.
I would say a bearing got damaged. But I would change oil and filter if you have not yet since overheat. Did you use ta cam bearings when you rebuilt?
yes, it overheated last year when the belt flew off, and a few months ago when the heater hose split. i've put about 1500 miles since the most recent overheat. oil has been changed every 3,000 miles since i built this engine. always clean, no metal in the oil.
oil pressure used to be 50-60 on the highway anytime above 3,000rpm, but now when it it won't crack 40 on the highway. maxes out at 35-40psi from 3000 on up. get off the highway and the oil calms down, it'll go above but not much.
cruise rpm is 3000, as the oil warms up i can watch as the gauge slowly goes down over about 10 minutes from 60 to 35-40, and it'll stay there as long as im at cruise rpm.
You're hemorrhaging oil. You may have wiped the front cam bearing, or lost enough Babbitt on main bearing(s) that clearences are opened up. Could also be oil pump, loose pickup tube, or anything causing significant "internal leakage" in the lube circuit. Checking the pump is about all you can do. Otherwise, your looking at teardown/inspection. You cannot drive this into a better state. That's like having severe chest pains and deciding to run to the Emergency Room.
Also check the relief valve in the pump cover, it might be stuck partially or fully open. Check the easily accessible stuff first
I'd say overheating has nothing to do with the oil pressure. I've towed a 19' boat with clogged radiator 200 miles round trip. Ran heater to pull engine heat away. Loosened rad cap to remove pressure, bought a 5lb radiator cap for temporary fix till the new radiator was installed. My t/c has 130k of use on it.
It has developed a cold rattle that goes away as soon as oil pressure comes up, but it only does it sometimes and rarely for more than 5 or 6 seconds.
Front seal on trans is bad and engine is leaking from just about every gasket so the whole shebang is coming out anyway.
Good idea, do an autopsy, see if you can pinpoint the failure. Take pics too! Did you happen to look at the oil pressure during the overheating?
