How to kill mold on billge/engine surfaces

ratdude747

Chief Petty Officer
Joined
Sep 30, 2023
Messages
425
Went to change my fuel filter today and discovered fluffy white mold all over the starboard side of the bilge around the gas tank and on the thermostat housing:16206.jpg

IMG_20260303_145729.jpg

For this situation, what's the best solution? Or will it resolve itself with time and use once the season starts?
 

Chris1956

Supreme Mariner
Joined
Mar 25, 2004
Messages
28,600
Bleach kills mold mildew and lots of other stuff. If using on fiberglass, you can use it full strength. If on vinyl or cloth, dilute it maybe 7::1 and see how it performs. Also, don't leave the solution on the vinyl or cloth for too long.

There are other mold killing marine products, however, if the surface is bare fiberglass, wood, plastic etc. bleach works really well.
 

ratdude747

Chief Petty Officer
Joined
Sep 30, 2023
Messages
425
Bleach kills mold mildew and lots of other stuff. If using on fiberglass, you can use it full strength. If on vinyl or cloth, dilute it maybe 7::1 and see how it performs. Also, don't leave the solution on the vinyl or cloth for too long.

There are other mold killing marine products, however, if the surface is bare fiberglass, wood, plastic etc. bleach works really well.
It's on braided fuel hose surfaces (filler and vent hoses), the painted fiberglass bilge wall, and a gasket joint between a painted cast iron thermostat housing and a cast aluminum intake manifold.
Per further review some of this was "dormant" in the past... seems the current temperatures and abundance of condensation has woken it up?

Bleach is what my mom used when we de-molded some of my dad's toys we recovered from grandpa's basement when I was a kid. But, I wanted to make sure that such is the right call here.
 

Scott Danforth

Grumpy Vintage Moderator still playing with boats
Staff member
Joined
Jul 23, 2011
Messages
52,095
Starbright mildew and stain remover

Or

CLR mold and mildew remover
 
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