Could use some advice what to look for, oil pressure wount go above 20 psi anymore, when cold goes to 40-50 for a few moments, ticking sound from valves /wrist pins/rocker arms ?, pulled the valve covers , oil flows as it should when idling, car does not smoke or consume oil, sound present only when below 2000 rpm ( or maybe cannot hear when revving), car was a trade in so no knowledge whats inside, head casts marked with 351 and 24, block 306 (bored once) ??
1. Replace the oil pump. If the pressure doesn't return, then 2. Pull the main caps and check the bearings. If they check out OK, then 3. Pull rod caps one by one until you find the bad bearing(s). Small possibility of an oil gallery plug came out, but most likely oil pump or bearing clearances. Oil when cold has enough viscosity to keep oil pressure up. When it warms up and thins out then oversize clearances in the pump or bearings lets too much oil by and pressure goes down.
Thanks for the advice, pulled the pump , seems like been scraped a bit against the cover plate but okay otherwise, no binding etc, "valve" ticking sound definately comes from around the valves, but checked the adjustment and seems ok.
Here's the bottom line: without oil pressure the engine won't survive. The oil pump may look OK but not provide the pressure. And, it may look OK and be OK and the problem be in the bearings or lifters. You're just going to have to look until you find the problem. Unless you have sufficient oil pressure to keep the lifters pumped up, they will "tick". I still recommend that you continue with the plan laid out earlier. Replace the oil pump. Check the bearings.
unknown total runtime on motor, everything seems tight underneath, replacing the original pump with a new standard flow pump today, gonna use the spare hi-flow pump later if needed, later plans include new cam and roller rockers if block not bored yet ( still to measure)
Cam bearings could be bad, or improperly installed. That usually causes poor oil pressure to the top-end...
If the new standard flow pump doesn't fix the problem, then there's a leak in the engine. Bearings, gallery plug, etc.
swapped to a new standard pump yesterday... ticking valve sound is gone now! so it seems that the pump was the culprit, developed a nasty leak though at the pan rear end rubber gasket, stupid of me not to change the "rubbers" only the cork gasket, so need to pull it off again!, idle oil pressure 13 psi, 30 psi at around 2800 rpm. Suspicious looking hand-cut "plate" between block and bellhouse? ( where starter connects to cog wheel) seems that the original one is missing?, this "plate" supports the rear end of oil pan? should i replace with original one? why has someone opted to rip it off in the first place??
You're still running a bit low on oil pressure. You might opt for a higer viscosity oil during the summer. That block plate doesn't support the oil pan. Yes, I'd replace it with an original one. They are fairly common. Check your local junkyard. BTW, congrats on fixing the problem.
changed to 15W/40 this morning full mineral, got 40 psi at 3000 rpm and 28 at idle!, no smoke and humming nicely, ( then again another sound present from the water pump i think or fan bearing)
Don't do any high rpm running with oil pressure that low.... Alternator, water pump and fan bearings all pretty much sound the same. You can eliminate the fan by removing it but the other two run on the same belt...
