Still overheating!!! HELP

[calincoltsdad]

I put a new impeller in the raw pump on my yamaha 4.3L V6 inboard and got alot more water flow to the engine. I have more water flow thru the exhaust and manifolds afterwards so I decided to go to the lake to try it. Anyway the temp still crept up slowly to between 175 and 200 so I went back to dock. I dont have the correct thermostat in but I do have the correct temp. range. Could this be the cause of the overheat? I've already checked all risers, manifolds and lines for obstructions. Can I run without a thermostat to see if the engine will run cooler or will marine engines overheat without a thermostat? I dont know what else to do.

 

[spktho]

Re: Still overheating!!! HELP

I would make sure to get the right thermostat. But you can test it out by heating it in water on the stove. Make sure you have a good thermometer to check and see at what temperature the thermostat opens at. I'm not familiar with your engine, so hopefully someone else can help more.

 

[WAVENBYE2]

Re: Still overheating!!! HELP

I dont have the correct thermostat in but I do have the correct temp. range. Could this be the cause of the overheat?

Have you check a manual or dealer to find out what correct thermostat your boat needs? I have a Mercruiser 4.3L V6 and my temp now runs steady at
150*, now that I have a new impeller, The other impeller that was taken out was still in good condition by looks but when running her at cruising speeds for long distances and then putting her at idle speed she would creep up to 190-almost 200* until the new impeller was installed and now 150* steady all the time idle-W.O.T.

 

[Hansolo99]

Re: Still overheating!!! HELP

Can I run without a thermostat to see if the engine will run cooler or will marine engines overheat without a thermostat? I dont know what else to do.

Yes you can run it without the thermostat. It will not overheat however it will run cold so as long as you are checking the temp you are fine to run it like that.

 

[calincoltsdad]

Re: Still overheating!!! HELP

The correct one is a 140. I'm trying to diagnose if I have another problem other than the thermostat. I was told some hotter without one. I've missed a whole month of riding trying to figure this out. What else can I try?

 

[dwmmatt23]

Re: Still overheating!!! HELP

The correct one is a 140. I'm trying to diagnose if I have another problem other than the thermostat. I was told some hotter without one. I've missed a whole month of riding trying to figure this out. What else can I try?

im in the same boat here, haha literally. i got the yamaha 4.3 as well and am looking for a replacement thermostat. do you know of any others that may fit?

 

[buddybarnhill]

Re: Still overheating!!! HELP

your tellin yourself the anserw over and over again you probably dont have anothere problem BUT YOU ALSO DONT HAVE THE RIGHT THERMOSTAT......

 

[1980Galaxy]

Re: Still overheating!!! HELP

don't run it without the t-stat. go get the correct one and put it in.

i just had an overheating problem, too. i changed the impeller and housing, still ran hot. so i took apart the t-stat housing and i had no t-stat in there. i bought a new t-stat and put it in there and it runs good now. i know it doesn't really make sense, you would think that it would run cool without the tstat but maybe the tstat was regulating where the water would go instead of dumping it all in the exhaust.