Burning oil

[Justafordguy]

I just had an odd problem start on my 77. Sometimes I will smell oil burning out of the left side exhaust. I don't see smoke but can smell burning oil. It only does it sometimes, randomly. Also when I crank it after it sits for a few days it will blow a bunch of smoke out the left side exhaust but not always, only once every few weeks.

It's a rebuilt stock 302 with about 10k miles on it and it runs great. I have checked the PCV system and the transmission modulator and both look fine. Any ideas? ?:?

 

[knack]

Oil smoke after sitting for a few days sounds like a bad valve stem seal or guide to me. Low mileage on that rebuild - bummer if you need to get back into the engine.
Hopefully someone will reply with the 10 minute fix.

 

[SHX669]

Exactly what Knack said -

 

[Justafordguy]

Yeah, I was thinking valves seals too but the randomness has me stumped.

 

[blubuckaroo]

I'd say valve guide seals too, but I'd do a compression check first. That will also give you an opportunity to look at the spark plugs.

The smoke only from one bank would eliminate a PCV problem but the cheesy baffles in aftermarket valve covers can allow some oil to be sucked through.

Another source for oil burning is through an intake manifold gasket. Did you happen to use FelPro 1250 intake gaskets?

 

[Justafordguy]

Hey Blu, good point on the Intake gaskets. I didn't assemble the engine, the PO had it built at a machine shop. I'll pull the plugs this weekend and do a compression test. Maybe also pull the valve covers and see if I can see a cracked valve seal. If that looks good I'll pull the intake.

 

[Apogee]

The blue smoke out the exhaust sounds like valve guide seals or any of the other things stated above, but the smell could be a variety of things. An oil leak onto the exhaust manifold from the valve cover gasket, oil sending unit, etc could account for the smell and may be inconsistent like you describe.

 

[blubuckaroo]

The blue smoke out the exhaust sounds like valve guide seals or any of the other things stated above, but the smell could be a variety of things. An oil leak onto the exhaust manifold from the valve cover gasket, oil sending unit, etc could account for the smell and may be inconsistent like you describe.

True. Look for a leaky valve cover gasket first. That could answer for the randomness of the smell of burned oil too.

 

[Justafordguy]

I did a quick oil leak check and didn't see any but I'll check closer this weekend.

 

[kip60]

Be sure and look down the back side of the engine. I've seen plenty of forum issues with the "hidden" oil leak out the back of the valve cover or back side of the engine.

 

[Justafordguy]

I don't smell oil up front and see no oil leaking. I only smell the oil coming out of the left exhaust.

I drove it this afternoon and no smoke at startup and no oil smell.