one greasy plug

[Marty Levenson]

I was checking my plugs yesterday and noticed the aft plug had a fair amount of thick greasy deposit on it. The forward three plugs looked clean and dry. wondering what could cause this?

thanks!

[Dave Neptune]

Marty, do a compression check. The aft cylinder #1 usually runs a bit rich due to the design of the manifold and a bit darker plug there is not uncommon. But oily residue indicates blowby.

If the plug was just wet you could have a weak ignition spark or faulty plug. Are you running stock plugs?

Dave Neptune

[Marty Levenson]

compression

Thanks, Dave. Will do. The engine is a Moyer rebuilt from May 2015. Seems a bit soon for rings?

Plugs are all the same type but forget which.

I do have the adjustable main jet (new this spring) - seems the front three plugs are well set, so doubt that's the issue.

[Marian Claire]

I once had a plug go bad. Caused the plug to be wet and fouled. I believe that led to stuck rings, oil usage etc. Try a new plug and see if it helps.
Dan
S/V Marian Claire
Just to confuse things here is that old post. http://www.moyermarineforum.com/foru...ead.php?t=4964

[Dave Neptune]

What Dan said and add a bit of 2-stroke (TCW-3 is best) or MMO to the gas so you are t around 100:1. The added oil will get to the cylinders and will often work sticky rings loose.

If you have an EI open the gap to about .045. This will create a bit more heat around the tip of the plug and aid in not fouling. If points try around .040. While you are doing this identify the fouled plug and place it in another cylinder. This will confirm a bad plug or bad cylinder.

A dry then wet compression check will yield good info too.

Dave Neptune