oil burning smell

[djmccallister]

I have a 90 gmc sierra 1500 4 x 4 with 52,000 on a "target" rebuilt 5.7 liter that has a oil burning smell. I have looked at the exhaust system and it appears to show no signs of oil. What could be causing this problem? Should I put an additive to the oil to help this situation? Any assistance would be great.

[C & A s Dad]

I am afraid an oil additive is not going to help you. If you can find no leak, I would suspect you have what is known as "blow by". This means compression is bypassing the rings and pushing back into the engine. I would suggest you take the oil cap off while it is running and see if you are getting any smoke coming out or can you actually feel any pres. coming out of this hole. Then do the same thing but pull your PCV valve and place you thumb over the end of the valve while the vacum line is still connected to it. See if you then get smoke or pres from the oil cap hole.

 

If so, this would indicate you have a compression ring issue.

[67ChevyRedneck]

I would check to see if the valve covers are leaking. It sounds to me that oil is leaking from the valve covers and dripping onto the hot exhaust manifolds. Are you having to add oil frequently? Can you see oil spray or leakage under or around the motor?