Gonna need a real pro to figure this one out.

I have a 355. it has a z28 oil pump with welded pickup and a mildon 30701 pan. It is supposed to be the correct pump/pickup for that pan.

The first symptom, was that the oil pressure became almost non existant after heavy driving. The car was very rich, so i changed the oil thinking it was fuel soaked. I also put in 20-50

Now the oil presure is normal, 19 at idle and 45 under accel (and higher when cold)...., EXCEPT that is drops into the low teens if I stay in it. Almost like its sucking the pan dry.thoughts ideas are: bad spring in oil pump, wrong pan to pickup clearence, or a missing galley plug or something.

one other symptom: I cut the oil filter open, there is NO metal in it, but there were shavings and small chunks on the magnetic drain plug. Could the filter be bypassed via the passage under the distrib? or the oil bypass glass by the filter? Could it be cam material? I do not hear bearing noise, plus bearing material is not magnetic untill its totally wiped out.

so, thoughts on low oil pressure under a WOT run with metal shavings on plu but not in filter? otherwise all else seems normal.

 

What gauge are you reading pressure with? How recently was the engine built? How high did you set the pickup above the oil pan? What kind of cam do you have?

 

Do you have a high volume pump with a standard size pan?
Have you checked the pickup to pan clearance?

 

mechanical gauge at the pressure port in the top back of block and an electric stock gauge off of the pan port. the engine is pretty fresh, but i built it, so i might have messed up. i didnt check pickup height, it was a welded on pickup that came with the z28 pump, and was supposed to fit that pan. hydrolic flat tappet cam. only getting 19 at idle though, so i think the bearings may be loosening, but, then again, no noise and the shavings on the drain plug were magnetic, and bearing material anint magnetic unless u get through it.. and again, no metal in filter.

yes its a high vol z28 pump and stock style pan milodon 30701 with the z28 melling pump

thanks

 

How long since you changed the oil after breaking in the cam?

 

i think i changed it after break in, it was a while ago. (not many miles on motor, but built it a few years back)

 

It could be leftover break-in debris.

 

yeah, but the big problem is the oil pressure dropping to low teens under acceleration...

 

You don't want to use a standard pan with a high volume pump. You should be using a 7 quart pan because the standard pan can be sucked dry. That is most likely why you have the low oil pressure or your pickup is to close to the bottom and the pan is getting sucked up to close to the pickup. I have seen some motors do that on circle tracks at the high RPMs.

 

so a stock pump or new pan. just bought and welded the pan for the blower