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Re: Silicone Valve Cover Gaskets and Some Saab Status Posted by eric in vermont [Email] (#2058) [Profile/Gallery] (more from eric in vermont) on Mon, 28 Nov 2022 10:21:57 In Reply to: Re: Silicone Valve Cover Gaskets and Some Saab Status, Charles, Sun, 27 Nov 2022 17:44:20 Members do not see ads below this line. - Help Keep This Site Online - Signup |
Hi Charles,
You could have a burned exhaust valve- that would be my guess.
That happened to me some years ago on one of my Sonetts. I had a bad front balance shaft bearing and pulled the motor to replace it. I also pulled the heads and had them sent out for valve grinding, just because it seemed like the right thing to do. They came back looking great and I promptly installed them. A few thousand miles later, I had low compression on one of the cylinders and it turned out to be a burned exhaust valve. I was curious as to why this happened so soon. I did some research and the prevailing thought was this: lead in the gas from the old days had coated the exhaust valves and protected them, even after years of no-lead gas. Once the valves were ground and lapped in, there wasn't any protection left and the valve burned. And there was a couple other exhaust valves that had started to burn.
So to fix it, you might think I put in hardened seats for the exhaust valves but I went the cheap route. I had a pile of good heads and simply replaced them with used ones. I bought a few cans of lead substitute and ran that for a while. No problems since.
So that's my thought...
eric in vermont
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