cooling water in Honda 50

rjmcnabb

New member
I have been plagued by poor telltale flow since I got Luna. Sid, our island guru, has done two Saltaway treatments, each of which helped a bit, but no cure. Next, he replaced the impeller, although when opened up the existing impeller was OK. Then he took off some kind of cover and could do some actual scaling of water channels. This week, water flow was intermittent and since I don't know how the thermostat works (on-off versus some proportionate kind of flow) I watched and waited: eventually, the water was quite hot, but I could stand it on my fingers, soI took her out. As soon as I took the rpms above idle, the overheat alarm sounded; drop back to idle and it went silent, water flow ragged, water hot but bearable. When I had the boat back in and secured to the dock, I revved her again (~2000 rpm or so) and this time the alarm sounded, the telltale stream was strong and the water was STEAMING! I shut her down and let her cool overnight before I tilted the engine to drain. I guess the next step is to try a new thermostat, but I don't see how a faulty thermostat could give these symptoms. Any advice will be appreciated, because my summer on the water is just "pissing" away. :sad
Thanks,
Rod
 
Hate that over heat alarm!! But, be glad it is there. There is always the possibility that the alarm sensor is goofy. Something for your mechanic to check. Stuck thermostats have happened to me on a couple of my older two cycle Evinrude motors. T-stats are normally pretty easy to access and should be replaced as one of the first attempts to fix your overheat problem. If the passages are blocked, there shouldn't be a variation in the pee stream. It is either good, slow, or bad. It should only be varying with RPM to some degree. If it is varying at constant RPM, then, of course the impeller is the first thing to be looked at, but you say it was replaced. Was it replaced properly? Mechanics vary from thugs to real technicians. I hope yours is the latter. Gunk in the water inlet screen at the bottom of the drive can give symptoms like yours.

The pee stream on my Suzuki motors is never more than slightly warm. If the pee stream is steamy hot, then there is definitely a t-stat issue or plugged passages. My experience is that if you have any active pee stream, even pretty slow, that your water pumping system is good. When he opened the motor up and cleaned the passage you talked about, was there, in fact, crud in there? If so, that means there is crud in places that he isn't able to easily get to.

Good luck, and please keep us posted on the ultimate solution for the knowledge base of all us CD boaters.
 
I agree, likely cause a stuck thermostat. I have replaced thermostats and impellers regularly on our Honda 40's and the pee stream varies from slightly strong to fairly weak. Neither has ever had a really strong stream. The stream water is normally slightly warm to the touch but never what I would call "hot". I flush the engines after every trip and use salt-away often.
 
A bit of an inconclusive update here, but might be useful, Jack in Alaska:
turns out the thermostat was bad, opening much too hot. However, running without the thermostat, the alarm came on after about 15 min. In all this the top cylinder (up where the sensor and thermostat are) was much hotter than either of the other two; best explanation for this seems to be a blown head gasket (guru and my wife's Googling skills agree on that.) :( Alas. Not something, forward to which, I am looking. :wink
 
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