[cldale]

Engine was dissesembled by mechanic shop and overhauled by machine shop including rebore and sleeve all 8 cylinders. New bearings, one new rod and piston, overhaul IP, new water pump.

After truck put back together there is no oil pressure! sending unit removed and mechanical gage installed, still no oil pressure. Removed gage adapter at block, started engine, oil oozed out but extremely low volume and pressure. What should I check next? Is there anything I can do before removing pan and pump which is a chore in itself? Oil pump appeared ok before overhaul but engine sat diassembled for about 6 months. Mechanic shop takes no responsibility since he didn't overhaul engine.

Engine will start and run but noisy tappets due to no oil pressure/volume.

Any help appreciated

 

[cdnsarguy]

Remove the filter and check the filter header for the presence of the pressure regulating valve....... a circular disc held in by a staked washer.

There is also a bypass valve in there...........

Look on my pics below my name...... select 90 per page there is a schematic of the oil system.

Did you soak the lifters before installation.......

 

[cldale]

I am checking with machine shop today. I suppose they whould have but not sure.

I will remove filter and check for regulator,Will the bypass valve prevent oil pressure/volume?

Thanks for input

 

[cldale]

Removed filter, the regulator seems to be intact. Filter header looks good. Guess I'll have to remove oil pump to see if thats problem'

 

[cdnsarguy]

Who installed the piston cooling jets, they fed from the same passage as the valve tappets......

 

[goinbroke2]

"Removed gage adapter at block, started engine, oil oozed out but extremely low volume and pressure"
Do not run the engine, pull the pan and check the pump, pick up and check for pickup to pan clearance. Forget about whats not sounding right or other things effected by the low oil pressure, find out why there is low pressure in the first place.

 

[Bill1013]

Some body is responsible for that, either the mechanic or the machine shop. We ain't getting the whole story. The oil pump, pumps a hugh volumn of oil even at idle, should be about 10 - 20 PSI at idle at 70-80 degrees ambient on start up. Did they rebuild the oil cooler with new O'rings? The oil goes directly from the pump thru the oil cooler, thru the filter, then into the oil galleries. Pull the oil filter and check the bypass valve, that is the stacked ring to the right in the pic, push it in with a screw driver it should have quite a bit of resistance, if not you have to grind the stacks off to remove the spring and valve. They had to remove the oil pump to do all that work, surely they put the key back in the drive gear. Any responsible shop would make sure the pickup screen was clear, and the bolts tight. Pickup screen should be about 1/2" off the bottom, there is kind of a guard on it so it can't touch the bottom of the pan.

 

[94_turbo]

Some body is responsible for that, either the mechanic or the machine shop. We ain't getting the whole story. The oil pump, pumps a hugh volumn of oil even at idle, should be about 10 - 20 PSI at idle at 70-80 degrees ambient on start up. Did they rebuild the oil cooler with new O'rings? The oil goes directly from the pump thru the oil cooler, thru the filter, then into the oil galleries. Pull the oil filter and check the bypass valve, that is the stacked ring to the right in the pic, push it in with a screw driver it should have quite a bit of resistance, if not you have to grind the stacks off to remove the spring and valve. They had to remove the oil pump to do all that work, surely they put the key back in the drive gear. Any responsible shop would make sure the pickup screen was clear, and the bolts tight. Pickup screen should be about 1/2" off the bottom, there is kind of a guard on it so it can't touch the bottom of the pan.

good post bill,,and agreed,,something aint kosher.....and depending on how long it has run with no pressure,,rods and mains probably are damaged...and hope the cam bearings aint toast...

 

[cdnsarguy]

As I read the posts..... I see nowhere where anyone did a prelube of the engine. Usually a requirement on totaly rebuilt engines if I'm not mistaken.

I agree running the engine more and more will not do it any good.

 

[LMJD]

I can't feature a genuine mechanic or machine shop doing this, but it sounds like the cam bearing oil holes may not have been lined up with the oil galley holes. Diesel engine oil pumps by design (compared to a gas engine) are pretty foolproof and trouble free. I don't know it all, but over the years I've about seen it all, a long time back the guy in the stall next to me pulled the pan due to a low oil pressure complaint and there was a shop rag tied neatly over the oil pickup screen. That's something we've all done when replacing rods and mains but it's advisable to remove the rag when done. So who knows, hard to say what you'll find?

 

[Bill1013]

Thanks to cdnsarguy,for the oil system layout and explanation for the 7.3 engine.

I for one would certainly like to know the outcome of the oil issue. Please keep us updated. It aught to be interesting.

 

[typefour]

The bypass under the filter wont affect oil pressure. That is to divert cold thick oil around the filter. The one in the header will. I would guess a pickup problem or the piston jets arent in, cam bearings wont cut oil to the sender port. It should be a geyser.

And upon thinking about this, I bet the galley plugs got left out of the lifter bores.!!!!!!

Oh and the oil pump didnt go bad sitting, they are nearly industructable. New melling ones have inferior quality control, I have one and dont like it.

 

[cldale]

Just to let everyone know, we are in the process of removing pan, pump etc. Will post a conclusion when we find out.
When I got the truck back it was run about 60 seconds max to check oil pressure.