Oily, dirty water leak

[SML Boomer]

I have a 1988 100HP Evinrude that has developed a leak from the exhaust gasket or maybe the powerhead base gasket. The liquid is black and oily but is mostly water and accumulates on top and in the crevices behind the thermostat housing. It has progressively gotten worse over a few months. I can clean everything off, make a short run, and then see seepage on the port, lower corner where the exhaust cover and powerhead bolt to the base. If I do a longer run the liquid will eventually fill up the crevices and spread pretty much all over the top of the thermostat housing. From your experience, which gasket is the most likely problem? If it is the exhaust I can tackle that today.

 

[ezeke]

Re: Oily, dirty water leak

Sounds like the exhaust gasket(s). Have you overheated recently?

 

[SML Boomer]

Re: Oily, dirty water leak

I did overheat briefly in Florida when hydrilla pluged up the thermostats. I replaced the water pump, thermostats, and the intake screens on the lower unit. This motor has the flatback exhaust cover. Other than warpage is there anything in particular I need to look out for when replacing gaskets?

 

[ezeke]

Re: Oily, dirty water leak

Nothing really outstanding. Relace both of the gaskets and clean the metal as well as possible. I use a high temperature gasket sealer on those gaskets unless the gasket face says not to. Permatex 1372 is good to 600 degrees. http://www.permatex.com/products/Au...72_High_Temperature_Form-A-Gasket_Sealant.htm