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My 6 week old project car is becoming a bigger and bigger project than I ever expected. Anyway, the 302 in it has an intermittent oil burning issue. Meaning, some times it will burn oil to the tune of a quart per 100 miles and some times it hardly burns any.

I first thought it might be caused by the previous owner's crappy hook up of the PCV valve to his crappy aftermarket foam air filter. There wasn't a spot for the hose from the PCV valve to be fed into the air filter, so he drilled one about 1/8" too big and used a bunch of silicone to hold the hose in place. I replaced the hose with a proper PCV hose instead of the vacuum tubing that was in place previously and this made for a tighter fit.

That seemed to slow the oil burning down some, for a while. But it only lasted for 1 or 2 drives. When I was adding oil for about the 500th time, I noticed the breather style cap had a poor gasket that made getting a good seal on the valve cover very hit & miss.

So, I replaced the oil breather on the driver's side valve cover, with a replacement that appeared to be identical. This made getting a decent seal on the valve cover much easier and appeared to fix the issue for a few drives. But the car is back to its oil burning ways now.

Any ideas on what might be causing this hit & miss oil consumption?

Neal
 

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Just a couple of questions.......Is it smoking under under throttle, or does is smoke when you let off the gas, or both? Also, pull your valve covers and check that the oil drain down/ returns in the cyl head arn't blocked by broken valve seal pieces. This will cause oil to stay in the valve train area and let some be sucked through the guides.
 

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Discussion Starter #3
Zaneh said:
"Is it smoking under under throttle, or does is smoke when you let off the gas, or both?"

And you're right it does these things, but only moderately and no more than I would expect from an engine of its age and abuse level. Remember this engine is consuming a quart of oil in less than a 100 miles, so I'd expect clouds of smoke behind the car if it was worn valves or rings.

Zaneh also said:
" Also, pull your valve covers and check that the oil drain down/ returns in the cyl head arn't blocked by broken valve seal pieces. "

This is a good idea and I was also wondering if the valve seals were bad. I'll have to pick up a set of gaskets and check this. Thanks for the advice.

Neal
 

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An itermittant oil burning like you suggest would seem to indicate to me that you might have a sticking PCV valve. If a PCV valve sticks, the crankcase will not be evacuated properly. This could cause pressure to build up in the crankcase. If pressure builds up in the crankcase, oil will try to go to the path of least resistance. Usually it will push the dipstick out, leak at any loose gasket, push oil out of the breather, push oil past the piston rings, or past the valve seals. For a five-dollar part, it can sure cause headaches!

If your engine has more than 30,000 miles, or has never been apart in its long life, chances are that the valve seals have hardened, cracked and gone to pieces.

Good luck and Happy Cattin'
 

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valve seals gone to pieces?? uh oh, so that must have been the crap in the heads when i pulled the covers. lemme guess, small, slightly circular O ring lookng crap right?? about ( maybe, from what i can guess by looking at fragments ) 1/2 in Inside Diameter or so? would i be able o chane those without pulling the heads?? i suck at mechanical work, im more of a body guy myself. i mean, a Dominator carb on a single plane can still do wonders for me, but a Sata Digital 2000 HVLP with a 1.3 head makes me shiver all over. :D
 

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oil burner

You shouldn't have to pull the heads, there is a couple ways around this. The first way is to put air into the spark plug hole with a compressor, this will hold the valve up while you change the seal. The other way involves pushing rope into the cylinder thru the spark plug hole, then rotate the engine by hand to apply pressure to the bottom of the valve. The compressor method is recomended. When you pick up the seals get the umbrella type seals they seam to work better on heads when the guides are worn.
If you have any plug fouling problems you could have a bad ring or they could have the grooves lined up close enough for oil to get through.
Good luck
John
 

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reading all of this reminds me...

why i usually sell cars when the warranty runs out.

it also reminds me why i never learned motor mechanics.:confused:
 
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