1996 Johnson 8 hp 2 stroke 'gunk' in exhaust

[WarthogMan]

My 1996 Johnson 8 hp 2 stroke has tannish grey 'gunk' coming out of the exhaust below the cavitation plate. I pulled the lower unit and the 'gunk' was all over the cavity in the mid-section. I checked the impeller and it was in need of replacement. I also noticed that when it was running the water pump periodically seemed to quit pumping water and then exhaust would come out of the weep hole. I'm going to replace the impeller but I think the bigger problem is that water is mixing with the exhaust somewhere. Does this sound right? Should I change the head gasket or is there a more likely place where this might be happening? Any insight would be greatly appreciated.

 

[racerone]

Re: 1996 Johnson 8 hp 2 stroke 'gunk' in exhaust

This has been observed many , many times.---------Water does indeed mix with the exhaust and it has to for cooling !-----What you are seeing is normal especially after idling in a barrel.--The nature of a 2 stroke engine.--Is the thermostat installed ?

 

[WarthogMan]

Re: 1996 Johnson 8 hp 2 stroke 'gunk' in exhaust

Thanks, Racerone. That helped a lot. I was running it in a barrel. What do you think about exhaust coming out of the pee hole when the water pump isn't pumping water? I'm in the process of replacing the water pump so I guess this shouldn't be a problem but I want to make sure there isn't some other problem that needs to be addressed. The reason I know this happens is that the old water pump would have periodic gaps for a few seconds where the water flow would quit and hot exhaust would come out of the pee hole. Thanks again.