burning oil

[laurie88]

i have 206 year 2007 PCM 330, done 600 hrs, i am constantly topping up with oil seems my engine burning too much oil. i have no visible leaks and no visisble smoke from exhaust and engine runs fine, anybody else experienced this, is my engine worn maybe? thanks

[skiinxs]

What temperature are you running? If the thermostat sticks, causing it to run too cold, you can make oil and burn oil.
Dave

[laurie88]

running 165-170 which is normal i think

[xrichard]

The oil is going someplace...so it's either being burned or its leaking out. How much do you use per 50 hr service interval? PCM has told me up to 1-1.2qts/service interval is ok. Above that is considered abnormal. If it's less than that and if it turns out to be difficult to identify or expensive to fix, you'll have to ask yourself if it's worth pursuing.

Your temp is normal. I'd do a compression check to see if there are any obvious problems (unfortunately, a compression check won't identify all ring issues that can lead to excess consumption). A leak-down test might be worthwhile, though it doesn't tell the entire tale, either. Also check that your pcv valve is not clogged.

Do you have any piston slap? IIRC, GM truck engines of that vintage have a known problem with piston slap and stuck rings. Another possibility is leaking valve guides--if you search on GM truck forums you'll see a lot of issues wrt defective guides (...I'm not sure that either of these issues apply to PCM marinized engines). Valve guides are a DIY item if you're careful.