Tohatsu 9.9B2 Thermostat Question

[tohatsu9.9guy]

I have a 9.9 Tohatsu 2 stroke, MS9.9B2 i believe, and I think it is a 1992 model. The other day I was trout fishing in my boat and my dad, who has an '89 model 18hp Nissan was in his boat. I noticed that my dads Nissan was pumping water out of the pee hole and out of the hole below the back of the cowl. My Tohatsu, however, was just pumping water out of the pee hole,and not from the hole below the back of the cowl. It was fairly cool outside and the motor ran just fine the whole trip. My motor has been shutting off occasionally in hot weather, and I would think it would be due to some sort of overheating. My question is this: Is water supposed to come out of the hole under on the back of the motor directly under the cowl on my 9.9 or just out of the pee hole? If so, would the absence of water being pumped out there be caused by a bad thermostat or anything else (clog, etc)? Any help would be greatly appreciated. Thanks.

 

[Sea Rider]

Re: Tohatsu 9.9B2 Thermostat Question

Should pee exactly the same as you father's 18 HP, if not probably low impeller pressure, thermostat failure or water passages obstruction issues. Back exit hole does not have pressure as to be felt with hand as the pee port does, water exists by inertia.

Happy Boating

 

[tohatsu9.9guy]

Re: Tohatsu 9.9B2 Thermostat Question

I stuck a spray straw up the port on the back of the motor while it was running and a clump of mud came out. After that it started pumping water out of the port somewhat, but not with a ton of pressure. I think i'll go ahead and replace the impeller and thermostat as well, if the impeller doesn't give it more pressure. It is an 18 year old motor, and i don't know if the impeller has ever been changed. At least it hasn't the 5 years that I have owned it.