waterpump queston

[Rumley]

If a thermostat fails and the engine overheats can this cause the waterpump in the outdrive to overheat and melt???
when i changed my impeller before my first ride there was signs of it overheating and partially melting. i ran the boat for 15 mins and it overheated, i have removed the thermostat and it looks like it hasnt been changed in a long time and am also changing all of the hoses because there is lots of rust flakes inside partially clogging the hoses.
anyway back to my question, do i need to pull the foot again and check the impeller to see if it has melted or should it be good??? thanks to anyone who can help...

 

[zx9rstv]

Re: waterpump queston

You said when you changed the impeller the first time. The old one was a little melted and overheated? Then after changing the impeller to a new one, the motor overheated after 15mins? Did it overheat prior to changing the impeller? Did you change the whole waterpump with a new waterpump kit? or just the impeller?

The impeller should still be pulling raw water in regardless if the tstat is opening up or not. Remember the tstat opens to let the ouside water flow through the engine. The water at the impeller shouldn't be super hot because it's what is pushing the water up to the water pump then through your tstat. There isn't cycled water from the engine that goes back to the impeller.
If you've run the outdrive out of the water , or not hooked up to running water on muffs even for a few seconds.
it can damage the impeller. So if you haven't done that I'd say you should be ok. but to be on the safe side. once you replace the hoses and tstat, run it on muffs, or on the trailer backed into the water for a good 10-15 minutes to make sure you're not over heating.

 

[Brentathon]

Re: waterpump queston

Overheating can definitely damage the impeller/housing, as well as other things. My over temp episode melted the impeller housing.
I would always play it safe when it comes to engine cooling......overheating is probably the most common cause of killing an engine.

 

[Rumley]

Re: waterpump queston

I had not run the motor prior to changing impeller. I bought the boat in winter. I talked to a few mechanics and they said that if the tstat isn't opening then the water isn't circulating so it can melt the impeller. Regardless tomorrow I am going to change the full waterpump not just the impeller this time. As well I am changing all the hoses because they are starting to crack and are filled with junk.

Does anyone know which thermostat should be put in it? It is an 88 350 mag 4bbl carb. On the diagrams from merc it is standard cooling design 2, but it shows that it could be a 140 or 160 Bodensee. What does Bodensee me? And how do I know if it is that or not? As well is there a disadvantage if it is supposed to me the 160 and I put in the 140? It will run cooler but is that going to do damage or lose performance?

Appreciate all the help anyone can give me