Thermostat won't close- Evinrude 50hp 72

[kippstakes]

Just received a replacement head in the mail which came with a thermostat (the head that was in my engine didn't even have one- is this okay? Is it preferable to maybe not have one and just let it flow? Seems like it wouldn't warm up. Anyway...). I tested the thermo in boiling water and it opened, but doesn't seem to want to close back up. What's up? It seems like it would be more likely not to open, and would always close under spring pressure.
Any ideas?

 

[Bosunsmate]

Re: Thermostat won't close- Evinrude 50hp 72

Yes not having a thermostat makes the engine run too cold, makes the owner seem keen on getting carbon deposits hurting the rings, bad fuel economy and risk of cold seizure, etc
Not sure why it wouldnt close, would it be the water pressure in the engine that would push it a bit further to close it?
You could ask the supplier too

 

[Bosunsmate]

Re: Thermostat won't close- Evinrude 50hp 72

How did you cool it after putting it in boiling water?

 

[kippstakes]

Re: Thermostat won't close- Evinrude 50hp 72

Cooled it by open air room temp. It's been sitting on the shelf overnight and still hasn't closed. These are a wax type thermo correct? Do you think wax loses its ability to expand and contract over many years? I guess the only other explanation is that it's binding somehow.
This thing's stuck hard, won't even budge
.

 

[Bosunsmate]

Re: Thermostat won't close- Evinrude 50hp 72

Yes itl be wax in there. Have you a picture of it?
If its the new one you a talking about id send a picture to the supplier and say this is whats happening to it.
You could reheat it and give it a giggle when wide open to check that everything is centred, but i know if i was out boating with that themostat that id be constantly wondering whats happening to it back there.

When i check a thermostat, i normally just heat it up slowly to 3/4 of boiling point

 

[boobie]

Re: Thermostat won't close- Evinrude 50hp 72

Send it back, it's bad.

 

[kippstakes]

Re: Thermostat won't close- Evinrude 50hp 72

Yup ordered a new one today. Nothing worse than worrying about your engine when you're on the ocean.
Thanks for the replies.