Heavy Oil Usage

[Edahall]

My 1982 6.2 Suburban burns a lot of oil unless I'm towing heavy loads. With around town driving, it normally burns through 2 quarts of oil per tank of fuel. I also get heavy blue smoke if I accelerate quickly or go up hills. When towing heavy loads, oil usage is greatly decreased and the heavy blue smoke dissappears. However, within 10-20 miles of city driving, the blue smoke reappears and oil usage is up again. Has anyone else seen this?

[john8662]

I'd pull a compresion test and see what you have. What kind of blow-by are you experiencing?

Blow-by will be seen by opening up the oil fill cap with the engine running and up to full operating temperature. If you remove the cap and it smokes a large plume of white smoke out of the filler, this is an indication of poor ring sealing/bore clearance excessive.

I have seen a few engines where the valve stem seals had failed, leading to oil consumption, and poor startability with knock until pooled oil cleared.

J

[Edahall]

I do get some blow-by when I open the cap. I don't know how to judge what is excessive. I'll try to take a video clip.

It has no problems with starting even down to 0 degrees. The engine has good power for a 6.2L. Gas mileage is high 20's on the freeway.

Also, I can keep the oil consumption down around town if I drive it hard by making sure I use heavy throttle when taking off from a stop. If I drive conservatively, the blue smoke starting creeping up very quickly.

The compression is probably low but I'll have to perform the test to confirm.

[john8662]

Also, do some reasearch on the forums on diagnosing a possible failed CDR valve. The CDR is very similar to a PCV valve on a gasser, and if this device has somehow been misinstalled or failed, you might see higher oil consumption.

[Edahall]

That's a good suggestion. I found the procedure to test the CDR valve. I'll give it a try.

http://blog.heathdiesel.com/2006/04/cdr-crankcase-depression-regulator.html