Exhaust substance on water pump housing

Kenneth82

Recruit
Joined
Aug 13, 2017
Messages
1
My dads 1992 mercury 40 HP wasn't pumping water that well so I tackled the water pump replacement this morning. In the process I found what seems like exhaust residue on top of the water pump housing. It is tan in color and smells like fuel. The exhaust leg seal was torn apart so I'm hoping that is what caused the problem. I am planning on replacing that seal. What I'm wondering is if there could be a problem elsewhere that was causing this, what seems like a large amount, of foamy fuel smelling residue to accumulate? I am a kid who is new to outboard repair and I'm really enjoying figuring this stuff out but I could use some advice. Could it be a seal elsewhere? I appreciate any advice very much.
 

Grub54891

Admiral
Joined
Jun 17, 2012
Messages
6,417
Welcome aboard. The residue is nothing more than unburnt fuel, oil, mixed with water. usually from running on a hose or in a test tank. Under load, in the lake the gunk simply goes away and cleans itself out.
 
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