When i start the engine i have appx. 20lbs of pressure. After the oil warms up and breaks down i loose all pressue. I can rev engine to 1700 r's and oil pressure comes back but anything less than that 0 oil pressure.
I have changed; timing chain cover (thats where the oil pump is), oil pump gears and the rod bearings. I still have the same problem with oil pressure. Anyone have an idea on what I can do to fix this? I am at a loss.

 

Is the oil pressure light turning on when the pressure drops? If not, then it could just be a bad sending unit... although it doesn't really sound like it.

 

Actually it has a factory gauge. I did put a new sending unit in just in case but if i let the engine idle long enough the rods start to chatter.

 

Bad oil pressure can also be caused by bad main bearings or even cam bearings as well. You may want to drop the main girdle and check out the mains. How did the original rod bearings look? Are you sure the old rod bearings were stock sized and not an oversize due to a rebuild at some point?

 

pick up screen could be clogged

 

Hans GZP,
The MB is my next step but with the cost of them i wanted a second opinion ya know. The rods looked wore but 7 & 8 were pitted a bit. I mic-ed the end of each bearing, they were all the same .062 the stanard size. Lookin at a rebuild soon huh?

 

VEETEN,
Soaked pick-up tube in engine degreaser for 24hrs. Looked brand new when I was done.

 

Was there any scoring on the crankshaft? Does it pass the "finger nail test"? Can you feel gouges with your fingernail?

 

verify pressure with a mechanical gauge.