Oil Burning under load

[bushw]

I have a 1985 M998 with the GM 6.2L Diesel with some issues. Off start the vehicle will run fine until the motor gets under heavy load, where it will start to smoke out the exhaust. Once the vehicle is warm, it will consistently burn oil and struggles to hit 30MPH. I just repaired an overheat issue with the truck, which turned out to be a bad thermostat, I am wondering if this has caused more issues. Any ideas out there?
Thanks in Advance!

 

[Coug]

You are sure it is burning oil? There is always the chance you have an issue with the injectors or injection pump.

What color is the smoke coming out the exhaust?

 

[bushw]

You are sure it is burning oil? There is always the chance you have an issue with the injectors or injection pump.

What color is the smoke coming out the exhaust?

The smoke is blue. It is unlikely that it is injectors or the pump as I had them replaced about 3-months ago with new parts.

 

[Coug]

how does the air filter restriction gauge look? I've heard stories about engines that ran fine until under a load and it ended up being a plugged air filter or even the mushroom cap on top got shoved down too far, preventing air from getting to the engine, which increased oil being pulled from the sump.

 

[papakb]

Compression check is in order. Especially after overheating problems.

 

[bushw]

how does the air filter restriction gauge look? I've heard stories about engines that ran fine until under a load and it ended up being a plugged air filter or even the mushroom cap on top got shoved down too far, preventing air from getting to the engine, which increased oil being pulled from the sump.

Last I checked the air filter, the filter did look new.

 

[bushw]

Compression check is in order. Especially after overheating problems.

Will try to get a compression test in soon. I think I hear some lifter chatter, but a friend disagreed with me, so that might be a potential issue as well.

 

[Milcommoguy]

Here you go....... Right out of the easy book.

BLUE SMOKE COMING FROM EXHAUST Blue smoke indicates that engine oil is burning in the cylinder or cylinders and may be accompanied by excessive oil consumption.

Some mechanical conditions which should be considered are:
• Stuck piston rings
• Worn piston rings
• Failed valve seals, worn valve stems and/or guides
• Faulty crankcase vent valve
• Cylinder walls out of round

Some non-mechanical checks include:
• Oil level too high (overfilled crankcase)
• Improper oil viscosity (too thin)
• Clogged CDR valve.
• Check for excessive blow by at filler tube

My little check here. Called the urrrha, urrrha, urrrha, urrrha test. Might have left one out...LOL
Pull IP fuel solenoid run wire. Does engine sound even when cranking over ?? Has in a same amount of head pressure / compression cycles times. YES/NO/ Can't tell.

Was there ANY maintenance checking prior to getting - running? Drain oil and check for extra parts large or microscopic.

Unusual sounds? ticking, tinking, screeching, rapping at idle. When you see the smoke, do you get a cold sweaty feeling and want to yell S*#t. ???

Peace of mine... and a small pain in butt, pull ALL of the glow plugs (test and replace later) and run the advised compression check.

May / will need a tester set up with glow plug fittings to get the proper seal and reading. Many gas engines tester are bit wonkie to get a good fit on the port or may not be able to read the higher pressures.

Disconnect IP fuel solenoid wire. ( already did that? won't start anyway) Keep fingers, tester and the other tester away from rotating parts. Have a co-pilot work the starter switch or starter remote switch for DIY.

Looking for NO LOWER than 380 PSI in ANY cylinder. Normal 400 +/- within 20 psi of each other. Should pump up quick, 3 seconds and read.

Have good batteries to spin engine 180 RPM. Should be real easy without glow plugs.

A little more history on the truck could help with the guessing. That burning oil, as in add a qt drive a bit, make some smoke and add a qt is worrisome and worries me.

Fingers crossed. Get ready to crack open the piggy bank and good luck. Most fun hobby around.

I worry and write too much, CAMO