Mercruiser I/O thermostate problems

[glmtrophy2352]

Was wondering if anyone was having problems or has heard of problems with mercruiser thermostates for 5.7 engines. I am on my fourth one and they all seem to go bad after one or two uses (engine run on muffs at idle)when first replaced they work fine no overheating but day or two later run the boat and it wants to run engine hot but manifolds are Ok temp. Am using heat gun to check and temps are getting to about 180-190 without thermostate opening (140degree) or am I missing something?

 

[chewy7097h]

Re: Mercruiser I/O thermostate problems

The thermostat controls the minimum operating temperature, not the maximum. You are overheating somewhere else - impeller, water pump?

 

[Bondo]

Re: Mercruiser I/O thermostate problems

Ayuh,.......

I gotta believe you have Issues, Other than a string of Bad T-stats......

I've Never heard of such a thing.....

Am using heat gun to check and temps are getting to about 180-190 without thermostate opening (140degree)

Don't you have a Heat Gauge,..?? What's It say,..??

 

[Don S]

Re: Mercruiser I/O thermostate problems

From your other posts, I gather this is all happening on muffs.

Back it down into real water and start it up and see what happens.

 

[glmtrophy2352]

Re: Mercruiser I/O thermostate problems

Headed out to the lake Wed. AM. will post Wed Pm on how it turns out.