thermostat problem

[jon middleton]

Hi

My 3.0 mercruiser is overheating , i have removed the thermostat and ran the boat and the engine temp is normal at 175f. I have installed a new thermostat and have run the engine and the temperature is high again at 200f? what can the problem be??

i have tested the thermostat in a saucepan and it opens fully at 165f .

please help!!

thanks

Jon

 

[bigskiohio]

Re: thermostat problem

175 sounds hot for no thermostat my 2.5 with will idle at 140 alot less on muffs and no warmer them 165 running on water.

 

[Bondo]

Re: thermostat problem

what can the problem be??

Ayuh,.... Change the Impeller,...
That's Always the 1st thing to do wit an Overheat diagnosis...

 

[jon middleton]

Re: thermostat problem

Hi

I have changed the impeller last night and is still doing the same things, overheating with thermostat in and running at just under 175f with it taken out. The exhaust elbow is cold when the thermostat is in and is warm when I run the engine with out the thermostat.
the thermostat housing is hot to touch when the thermostat is in place and engine running?

Do I have a blocked thermostat housing? or something more sinister?

Any help would be great!

Thanks

 

[bigskiohio]

Re: thermostat problem

start it and pull the hose coming from outdrive at the front of motor and check your flow. should be pretty good flow. is it in the water or on muffs i have checked that on the water i dint know how that would be on muffs water pressure.