Bad valve seal?

[rmcdaniels]

Is this valve seal bad?

First pic is of one that looks like it is seeping, second pic looks like the rest of the valves.

[HONDA GHANDI]

Thats a bad seal or bad guide causing the valve to "rock" back and forth opening up the seal and allowing oil past. B series guides are not that easy to do and it took my machinist a few times to get it perfect. Now that he knows what he is doing he is flawless at it.

[rmcdaniels]

Thanks, that makes sense. Do you think it's worth fixing it now? I haven't had any problems with it so far and it's not leaking enough to get in the cylinder. Is this something that can wait?

[doctorstupid]

Unless I'm mistaken, that's a valve guide and not a valve stem seal....?

[rmcdaniels]

Well, it's actually a guide, part of a stem, and an exhaust port, but I was referring to the part that is letting the oil get where it is. Not much point taking a picture of the seal as it will look fine.

[doctorstupid]

Hahaha, OK, seemed that should have been cleared up first :p

As long as you're pulling the head for a gasket, might as well take some time to figure it out, though most likely it's just a leaking seal. But if it's a worn guide/stem you might as well determine and fix that now insteald of pulling the head again jsut as soon as it's bolted back on.

[HONDA GHANDI]

Roger, the seals never fix themselves so if you have the head off its an easy fix. Well worth it in my experiences.


Dr., it is a pic of the guide but the guides should not have any oil in them. They dont seal at all so any oil seepage would have to come from the seal. Now as far as why the seal is leaking that would be another story. Bad seal installation, bad guide install, worn valve stem, a bur on the top of the valve could have cut the seal, etc.

[rmcdaniels]

Well, I'm glad I took it in. Three bent exhaust valves so far. Still trying to figure out what the valve guide clearance should be, Ferrea says 1.2/1.5 and the guy who built the head says 2 because of the amount of boost I am running. Anyone here build B-series heads for a living?

[rmcdaniels]

Curiouser and curiouser, just in case anybody is still reading this thread:

Told the head builder Ferrea didn't agree with his numbers, he said I talked to the wrong guy and gave me the name of the right guy. Called Ferrea back and got the right guy, and he told me it should be .0006-.0008 on the intake and .0012-.0014 on the exhaust, and that a clearance of .002 might cause the seals to leak, just like Tobi speculated. It's at the machine shop now, I'm curious to see what the clearances actually are.

[rmcdaniels]

Back from the machine shop, and all the valve guide clearances are .0015, which is actually not bad. Three slightly bent exhaust valves and some head warpage requiring .004 of milling. All in all not bad for a year's worth of >250BHP/liter. Now to see if I can keep abusing it for another year without throwing a rod.