The Stovebolt Site Forums The Shop Area Engine Shop fresh rebuild lifter noise &pressure problems

Hey guys

I know its not an L6, but i thought maybe i could milk your expertise anyways. I recently finished a total rebuild on a GM 2.8 V6 to put in my Chevette(the winter beater when the truck's away)A milodon High Volume oil pump was installed along with a new RV cam and lifters. I got the valves all set up and the motor was running fine. I get around 70 PSI when I fire it up, and it runs nice and quiet. However, within 10 minutes, the pressure has dropped to almost 0 and the lifters are clacking up a storm, and power falls off quite a bit. What gives? did i screw things up by adding a HV pump? Did i maybe leave an important bit off when i put everything back together? I know my oil pan got a little ding (a 1/4 inch deep at most) in the bottom-could that have dislodged the pickup? im at my wits end, and praying that someone elses experience may save me tearing down my fresh motor. Thanks!

Maybe the pump is starving for oil if it is made for a larger pan capacity. Just a thought.

Pressure is one thing but volume is quite another.

I've never seen a Chevette with a V-6! Is that an add-on engine, or do they do things different up there? :confused: :confused: :confused:

The early 2.8's such as the one I rebuilt from my Brother's Chevy Cavalier had chronic oil pressure problems, and among other things, we found an oil passageway from front to rear drilled off-center which was starving one of the main bearing journals for lubrication. He had bought the car with a bad rod bearing, and we drilled the passageway straight with an extended-shank drill bit, and installed a high-volume pump. No problems for the next 100,000 miles!

It sounds like you've got a major pressure loss somewhere, either a sticky pressure relief valve in the pump, or some other catastrophe. Pull the engine and dismantle it before you have a major failure, and look for oddball things like oil passage problems. The early 2.8's were not good engines!
Jerry

I got the 'vette with a 4 banger and yanked it for the 6, although GM did make a few in the early 80's for testing (never made production cos they were faster than corvettes!) I got the motor second hand and one of the rods had actually come undone about 1/2 an inch, making for a nasty knock and a cracked crank. I dont know the previous history of the motor, so i dont know about the proper pressure to begin with. getting to be very sorry i invested so much $ and time into such a turd...a buick 3.8, thats the way to go!

oh yeah, the pressure goes back up with RPM, so i dont think im lacking oil in the pan, and im sure i got the proper pickup for the pan...

You've got a stuck relief valve. Yank it out, and either replace the pump, or do a mirror-polish job on the relief valve with a felt wheel and jeweler's rouge. Check the valve bore for scratches, also.
Jerry