Over heated!

[Phantom383]

Have had my boat in several small inland lakes with no problems so I decided to take it out on Lake Michigan to do some perch fishing.
Everything went well going out but coming back in I blew antifreeze all over out the Radiator cap & shorted my system out so I waited for a tow.
Motor hit 240!
Any Ideas?
It's a Merc 485 I 4.
The water pump pumps water in the driveway with the muffs on but I'm wondering if that is forceing water into the system that way?

 

[stonyloam]

Re: Over heated!

When is the last time the impeller was changed? Since you overheated it you need to do a compression check and cooling system pressure test borrow the tools from Autozone. Good luck.

 

[southwest395]

Re: Over heated!

I agree with stonyloam. Probably need to impeller and hopefuly at that temp you did not worp the head or the block. Hopefuly worst case is just a head gasket good luck

 

[Silvertip]

Re: Over heated!

Running on muffs of course water is being forced into the system. Water gets through the hose to the engine under whatever the city water or well fed water system pressure is. Even with no water pump water would still make its way through the engine.

 

[Phantom383]

Re: Over heated!

The whole motor and lower unit and water pump were rebuilt last year.
Going to see if I can rotate the motor by hand and go from there.
Thanks for the input.
What is the kit from AZ?

 

[stonyloam]

Re: Over heated!

What is the kit from AZ?

Their lend a tool program, they will lend you the pressure test kit and compression tester.

 

[Phantom383]

Re: Over heated!

That would hook to the radiator cap then?