Posted by David Sherman on Tuesday, February 21, 2006 at 6:56PM :
In Reply to: Re: what is the problem with your engine ? posted by Howard in Newcastle on Tuesday, February 21, 2006 at 3:11PM :
Not like new, but it does the job. If your only problem is #6, investigate that a little more before you go for a rebuild. Do a wet compression test (squirt oil into the cylinder). Make sure it goes into the cylinder, not just down the spark plug hole, because the spark plug isn't over the cylinder on a flatheat. If that doesn't bring your compression up, you've got a burned or stuck valve. If it does bring it up, pull the head (which you'll have to do anyway for the valve job) and see how the cylinder looks. Check for scoring and check the ridge at the top. If the ridge is about the same as on the good cylinders and there's no worse scoring than the other cylinders, you more than likely have broken rings. In any case, at that point, drop the pan, unbolt the #6 rod, ream the ridge off the top of the cylinder and push the piston out. With the piston out, it should be obvious what's wrong. You might need 1 new piston. You'll definitely need new rings. Or, as soon as you get the head off, you'll know it's a valve problem. It's a little trickier to grind a valve seat on a flathead because you can't just take the head to a machine shop and most machinists don't make house calls, but you can figure something out if it comes to that.
Regardless, I'd say that with 100 psi on #1-#6, and good oil pressure (meaning good bearings), this isn't an engine that needs overhauling right now. We're a lot more eager to completely overhaul an engine nowadays than guys were in the old days. A lot of engines got a rod bearing done here or there or a couple of cylinders done, or maybe they'd just freshen up a tired engine with a valve grind and a ring job. There's nothing that says you have to totally overhaul an engine just because it has a problem on one cylinder.
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