Low Oil Pressure

[TORQUEMADA]

My '94 K 3500 TD is dropping to 0 pressure at idle after warming up. Both OE gauge and mechanical read the same, and trigger the check instrument light on the panel. 30 to 40 at operational speeds, 50 to 60 when cold. Who makes a high volume pump for this engine? And, how tough is getting the pan off a 4X4?
PS, this has been ongoing, hope the bearings are still there. :(

[JoeyD]

I would't run it again until you fix the pump. You need to drop the front axle ass. out to do it. It's not that bad just takes some time.
As far as oil pumps maybe you could use the one off the 97 and later motors as they added the piston oil coolers that year and made the pump better to supply oil to them.

[toyboxrv]

I have a 94 and put in the 97 high volume pump. I didn't remove the front dif, only removed the bolts to get clearance. I did remove the engine mount bolts and lifted the engine up. If your pressure is that low there may be some other problems like excessive bearing wear or lifters that leak down too much.

[TORQUEMADA]

Thank you for replies. This engine is from Brooklyn and was a GM test engine, manufactured in '98. I did an internal inspection before installing it 8000 miles ago. It was very clean, and bearings looked new. It has performed flawlessly. I could not find the piston oilers, but wasn't sure what to look for. I replaced the OPS with a Neihoff brand when the original started leaking. I ordered it for a '94 without thinking, so later blamed low oil pressure on thathat sensor. Having just installed a mechanical I was irritated finding it matched the electronic gauge, and 0 oil pressure at idle. I'm guessing that the oil pump is the high volume pump, and if it ain't bad, then I got trouble down below. I'll check the mains when I get it apart. Not this week, tho. It's parked.

[mhagie]

In ordering a OPS for a 94 you were correct in doing so, IMO the sender should match model year of truck so the sender and gauge are compatible, anyway the block dosen't have a clue what year it is anyway.
I am sure that others more knowledgable than me will respond here but I would be very suspect of a engine that is claimed to be a test engine from GM, that has been a marketing ploy for years to sell used engines in varying conditions.
It would be advisable to plastigauge the mains while you are in there if for nothing else than peace of mind, its best to know what you have rather than guess.
Oil pumps can and do go bad but these engines do not have that rep for pump failure.
whatever the case Good luck to you in this endever. smile.gif

[GARY PAGE]

Check the mains first if thats OK it's the cam bearings. Rods have very little effect. The first bearings to get oil are the cam bearings so if they don't seal it's all over. I had an engine with 210K miles act the same way. The previous owner negelected service. The bearings were almost worn thru to the block. when I got it torn down. Good Luck