Changing the Thermostat

[jchurch6713]

Has anyone got any experience changing the thermostat on the mercruiser 350 mag mpi? It is a 2001 model.

[moved2ski]

yep, The thermostate is held in a plastic housing inside the thermostate cover. I used WD40 and worked slowly and carefuly to get the old one out with out breaking the plastic. Take the thermostate with you to the auto parts store. It is smaller in size than a standerd 350 chevy. I alos had to use a razer knife to modify a gasket from the standerd chevy gasket. Good luck.

[R&T Babich]

Are you sure you need to change the thermostat?
What are the symptoms?
You may have a clog somewhere or your raw water pump impeller would be the first places I would check.
The thermostat in our engine is probably: 160 deg - 807252T-2 (Mallory Marine thermostat - 9-43002, kit - 9-43157)

[jchurch6713]

Got the problem fixed, put on a new impeller and housing. I did not think that it was the thermostat but I wanted to go ahead and find out what it would take to replace it because I was on a mission to get on the water yesterday. We made it out and the boat ran good other than a vapor lock issue, cooled the engine and was underway again. Don't know how I am going to fix that I just put on a new fuel pump/cooler and pressure regulator. The funny thing is that I had a buddy go out with us on his boat in case I needed a tow or anything and on our way back to the ramp his boat broke and I actually had to tow him back. He has an I/O and we think the shaft on the outdrive broke. It will be fun to fix. As always thanks for all the help.

[dogbert]

We made it out and the boat ran good other than a vapor lock issue, cooled the engine and was underway again. Don't know how I am going to fix that I just put on a new fuel pump/cooler and pressure regulator.

With more ethanol in the gas these days, this problem will only get worse. The easiest way to solve it is to run your blower for a few minutes to change out the air in your engine compartment. That works for me every time.

[TeamAllen]

In addition to running the fan, I let the engine idle for a minute or two, after a hard run, before I shut it down.

Have you checked the anti siphon valve?

[samw]

In addition to running the fan, I let the engine idle for a minute or two, after a hard run, before I shut it down.

Have you checked the anti siphon valve?

X2

[TeamAllen]

I noticed after a hard run my temp gauge would climb a little. Not much, maybe 5 deg. or so. After I brought the boat to idle I would see the temp. gauge dropping. Maybe I need a new T-stat? But, it is just something I noticed.