Okay so just got done doing a leakdown test! Found one bad exhaust valve. Question is has anyone had a leaking exhaust valve from just carbon build up? I was talking with a friend and he said he changed a head on are buddys evo and the carbon build up was crazy. He thinks maybe it could just be that and to use seafoam? What do you guys think? What would you do also if you had to pull the head change the one valve or get a ported head new valves etc? Any and all information is great!

 

Just replaced one valve that had so much carbon build up it was rediculos

 

Carbon could build up enough to keep the valve from seating and cause a leak. Try sea foam and do a retest after a bit.

 

Seafoam in the gas tank? Oil? Dump some down the spark plug hole and crank it over by hand?

It seems like anything going through the combustion cycle won't be able to clean off the exhaust valves very efficiently.

 

...seafoam, lol, i dunno man i wouldnt run that stuff in it. just think it's gonna get pumped thru ur turbo bearings too. i dunno i dont ever see any real studies of anyone who tore a motor apart and then put it back together and then ran that stuff to document how well it actually works...or not, i just dont trust it. neone else?

 

Anyone else?

 

I saw seafoam recommended in several places and tried it out to solve an issue with the same symptoms. It didn't seem to help.

Somebody else recommended Marvel Mystery Oil and I'm running with that right now. I've had it in for some 700 miles and the symptoms are slowly getting worse. (Likely not due to the MMO, but still not getting better

I'm afraid I'll have to pull the head before I do too much damage to the engine waiting. still, so many people have recommended it you'd think people see results, so maybe you'll have better luck than me.

I'm also curious to hear answers to your question about just replacing the one valve or getting more done while the head's off, since I'll likely be doing the same. How about just new springs, retainers, and valves?