Merc 140 Alpha 1 thermostat deep fried. question with photos

[chadnort]

Im hoping this is what caused my overheat on the lake last Saturday. Was out for about 30 minutes and the temp gauge hit 250F. What looked like steam was coming from the exhaust, shut down and cooled off but after an hour she would not start. Im replacing the thermostat and impeller, charging the battery and crossing my fingers. Question is, how concerned do I need to be about what is not in the picture? I'm refering to the various metal bits that have obviously broken off the thermostat. Will it just end up exiting with the exhaust, or rusting away? Do I need to dig it out or is it OK to let it be? Again any post is welcome...

 

[Fordiesel69]

Re: Merc 140 Alpha 1 thermostat deep fried. question with photos

I had one brand new DOA out of box. Overheated instantly but did not fall aprt. Engine is toast if it would not turn over.

 

[cr2k]

Re: Merc 140 Alpha 1 thermostat deep fried. question with photos

More likely the thermo was fried due to the impeller. Make sure you find each and everyone of the impeller pieces or you will be back doing later.
Also check your exhaust tubes without water they fry from the inside.

 

[chadnort]

Re: Merc 140 Alpha 1 thermostat deep fried. question with photos

Replaced thermostat and charged battery. Motor ran fine with no heat issues at least on muffs anyway. I guess as long as the thermostat parts made it past the water shutter (assuming its still there) I should be in the clear. Again, I will replace the waterpump/impeller unit at end of season or beginning of next...

 

[EddiePetty]

Re: Merc 140 Alpha 1 thermostat deep fried. question with photos

"..... I will replace the waterpump/impeller unit at end of season or beginning of next... "

WAIT A MINUTE...WAIT A MINUTE!!!!!!

You had a drastic overheat and you're not even gonna inspect the impeller pump !?!?!?!?

Remember now, when on the muffs the cooling water is being pressure fed into the impeller pump, so in theory, you wouldn't even need an impeller.

 

[Fordiesel69]

Re: Merc 140 Alpha 1 thermostat deep fried. question with photos

Your impeller is now toast even if it was brand new a week ago.

You are forcing city / well water pressure into the drive. It will cool even with a destroyed impeller.