# Spark plug question



## KeepingItSimple (Mar 20, 2011)

1983 merc 25hp
Runs reasonably well. There are some idle issues that I've been trying to work on. I have replaced the spark plugs a couple of times now. After maybe 6-8 trips they look like this. When I change them the motor runs much better. I've never seen an outboard do this before. Any ideas? I am using the plug that is recommended for the motor. Almost like they are running too hot?

These plugs were new a month ago:


----------



## DuckNut (Apr 3, 2009)

Looks like the plug if firing fine but you are getting water under the cowl- either from spray or when washing.

Clean everything and spray it with a corrosion inhibitor.


----------



## Tommysmicroskiff (Jan 19, 2012)

Everything duckNut said plus look for a stainless steel equivalent plug 



> Looks like the plug if firing fine but you are getting water under the cowl- either from spray or when washing.
> 
> Clean everything and spray it with a corrosion inhibitor.


----------



## Tommysmicroskiff (Jan 19, 2012)

Here you go  the 5939 QL87YC

http://www.fishing-catalog.com/other%20products/spark_plugs.htm


----------



## Brett (Jul 16, 2008)

Also check for a gasket leak/bleed dripping from top to bottom.
I've had that happen between the water cover and cylinder head.
Salt deposits will lead to the source.


----------

