Burning Oil
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Senior User
Joined: May 2007
Posts: 218
Likes: 1
From: Everett, WA
Burning Oil
I have a 1970 302. I can tell you for sure I am burning oil. The cloud of smoke when I start the engine seems to be a dead giveaway and the smell and dirty breathers just re-affirms it. I did a compression test and all my readings were between about 125-140 psi so my compression seems good. When I got my plugs out, all of them have a nice black color to them. My guess is valve seals, sound about right to the rest of y'all? Are there any other things I should be looking at? Also, I noticed my #8 spark plug was incredibly clean compared to the rest, any ideas why this could be happening?
Lead Driver
Joined: Jan 2003
Posts: 9,893
Likes: 12
From: Ohio
The compression rings may be in decent shape, but the oil control rings might be weak, thus causing burning also. Valve stems will cause the big burst at start up. If it's not been touched, then likely the original umbrella seals are hardened and/or gone.
Lead Driver
Joined: Oct 2004
Posts: 8,062
Likes: 35
From: Central Oregon
If you are getting smoke at start up, IMO you are right about the seals leaking oil after the engine stops. Pull valve covers and make sure the oil return passages are not pluged. You can change the valve seals with out pulling the heads, using air pressure or small size cord in the cylinders, to hold the valves up in place as you remove the valve springs.
