scottba 0 #1 Posted April 23, 2011 After running steady for an hour or so, my M12 stalls, usually with a loud backfire or two. Immediate attempts to restart are unsuccessful and it seems to have complete loss of compression. After just a minute or two, it cranks right back up and runs great otherwise; no smoke & no unusual oil use or loss. Ordinarily it has no starting problems - either hot or cold. Suggestions? Head gasket? Could the oil sentry protection feature be faulty? Share this post Link to post Share on other sites
Duff 206 #2 Posted April 24, 2011 Bruce, ! Glad you found us, and thank you for your service! My Dad was in the US Army Air Corps in WWII. Except for the loss of compression I would have said there's a fuel deilvery problem, either air locking or the carb float hanging up. The compression issue would seem to suggest a valve is hanging. There are a bunch of guys around here who are real pros at engine diagnostics so I'll be watching to see what they have to offer. Duff :thumbs: Share this post Link to post Share on other sites
JC 1965 1,528 #3 Posted April 24, 2011 :wh: Sorry I can't help with your problem but and thank you for your service to our country. :thumbs: Share this post Link to post Share on other sites
gwgdog66 23 #4 Posted April 24, 2011 :thumbs: I've never worked on a magnum, if it was a K series I might could lend a few points. I think Duff is on the right track. Maybe one of the Magnum guys can help you out. Share this post Link to post Share on other sites
