Oil Burning
Thread Starter
Instructor
Joined: May 2006
Posts: 135
Likes: 0
From: Hot Springs Village AR
Oil Burning
Need help diagnosing oil burning. I have 5,000 miles on my modified 71 350 engine. It burns oil (blue smoke) out of the right bank. Performed a compression test with all cylinders between 155-160 psi. Performed a cylinder leak down test and all cylinders show between 7-10% leakage. This picture shows the #2 plug major oily with deposits: #6 with major deposits and all other plugs look like #8. #2 cylinder reads 155 psi and 8% leak down. #6 is 155 psi and 7% leak down.
1.Can you have good compression and leak down readings and still burn oil thru the rings?
2.What I'm thinking is that it is leaking (sucking) oil into the intake due to gasket leakage. The block has been decked and heads slightly milled. The intake is stock with no machining. This could result in a mismatch of the intake to head.
What's your take?
1.Can you have good compression and leak down readings and still burn oil thru the rings?
2.What I'm thinking is that it is leaking (sucking) oil into the intake due to gasket leakage. The block has been decked and heads slightly milled. The intake is stock with no machining. This could result in a mismatch of the intake to head.
What's your take?
Melting Slicks
Joined: Feb 2006
Posts: 3,428
Likes: 5
From: Japan
I am 98.3% positive that your #2 suspicion is the correct one. My 'machinist' milled my heads without my prior consent, and I suffered through endless headaches and two more engine removal/rebuilds before I finally broke down and re-machined the heads to correct the angularity issues that machinist #1 had caused. Went from 1 qt./100 mile oil consumption to zero. You can try re-sealing the crap out of your intake but with all the machine work you had done be prepared to go way deeper. Best of luck!
