Yamaha 25DM Overheating/cut out

B

Bob_up_and_down0

Recruit
Joined
Oct 26, 2009
Messages
2
Hi Guys and Gals, I have a fantastic old Yamaha 25DM starts, idles and runs great for about 10 minutes then it boggs down, overheats and cuts out.

I have replaced the impeller, and it pumps water fine in the tank or with muffs on, pumps fine in the sea as well but after 10 mins she loses the tell tale and starts to heat up. Previously the thermostat has been removed. Could it be the head gasket? Am a bit stuck with what to look at next any help/suggestion greatfully recieved.
Thanks
 
9

99yam40

Fleet Admiral
Joined
Sep 7, 2008
Messages
8,877
Re: Yamaha 25DM Overheating/cut out

Water cooled motors need to have the thermostat in place for a restriction to force water into all the passages for proper cooling. They are easy to test in a pot of water to see if and at what temp they open and close and how far they open.
I kind of doubt that is your only problem, but you can never be sure unless you try it though, probably need to pull head to check gaskets and passages for blockage.
 
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