'87 R1500 4.3L Oil Consumption

[Nuckollsr]

I inherited a one-owner '87 from my father about 12 years ago with only 35K miles. But door hinges were worn out, headliner was down, seat covers trashed. Ran well but had a host of little problems more related to age than mileage. Thankfully, almost zero rust.

Over the years, we've 'spruced up ol' Blue'. No oil leaks. Finally have engine 'broke in' (85,000 miles). Have a long list of weekend projects intended to extend longevity and enhance appearance. I have a nagging problem on which some of the old salts here might offer enlightenment:

The engine uses about a quart of oil every 200 miles or so. Tailpipe is black. Exhaust doesn't visibly smoke except about every 10th start up, it 'puffs' a little smoke which quickly clears. I've replaced seals on the valve stems and cleaned passages down through the heads/block which had become badly gunked-up causing oil to pool under the valve covers.

It's not a really big deal given that the truck is running well. I've got lots of other things to do to it . . . new dash cover, electric cooling fan, fix flapper door actuators in HVAC, etc. etc. But given that my other cars with 160K and 203K miles use no oil between changes, this little ol' truck's oilaholic behavior is a nagging condition I'd like to fix.

I'm an aviation electron-herder by experience so swinging wrenches on things that go around fast is a new field of educational endeavor. Does anyone have suggestions as to how oil is getting into the wrong places? Seems that options are few . . . but ideas from more experienced custodians of these venerable machines would be most welcome!

 

[Old77]

I've moved this to a more appropriate subforum out of the Intro section for more appropriate attention to your issue.

Welcome to the forum.

 

[1985c20]

Does it still have the catalytic convertor on the exhaust? If it does it could be filtering out the smoke so you're not seeing it. This will quickly plug it up if it is. Have you checked the antifreeze to make sure its not ending up there? a quart every 200 miles is pretty high usage. There's really only 3 places the oil could be. The antifreeze, burning in the combustion chamber, or externally leaking somewhere. Might want to do a compression and/or leak down test.

 

[Charlie]

 

[Frankenchevy]

Was the consumption that bad when you first got it?

Pulling the plugs will be worth while. If the trucks mileage was actual mileage when you got it, it could have a stuck ring. You’d think that would’ve freed up by now. If you have a compression tester you can run a wet vs dry compression test in any cylinders that are suspect.

As others have stated, it either ending up on the ground, which you’d likely notice; in your coolant; or burning in your combustion chamber.

 

[CSFJ]

Iirc, the early 4.3 engines had a consumption problem. I want to say it was the #6 and possibly also the #4 cylinder that did it. Can't recall what the root cause was anymore.