Cruising my Donzi back home yesterday I felt the steering wheel freeze up? It would still turn left but right was very stiff. I figured I broke one of the 3 V-belts. Fortunately, I was just coming up on the channel and then slowed for the no wake zone. I was only cruising at 3,500rpm. that's when I noticed the water temp bouncing between 235-240*...... I headed for my dock at idle power for about 2 minutes and shut it down. I do have a Monitor closed cooling system and when I popped the hatch there was anti-freeze in the bilge and the overflow tank was full........ The alternator belt snapped and must have derailed the power steering belt when it let go as it was laying in the bilge. Obviously, there was nothing turning the circulating pump pulley so the reason for the overheat seemed obvious..... Sea water pump/fuel pump unit was fine and works as advertised. I let it all cool down for a couple hours and put the power steering belt back on. I figured I was good to go as it would drive the circulation pump. I fired it up and thought it was good to go but it still got hot?? I let it cool down again and hooked up the remote hose flush plug and turned it on..... fired it up again and plenty of water coming out the exhaust just like normal........ watched temp gauge climb fast again and new it was going hot so I just shut it down...............motor is a 502 with V-belts with aluminum heads/exhaust. I use 93 octane and the motor never knocked one time and runs fine.........

If plenty of water comes out the exhaust I would assume the sea water pump is good? it is newly rebuilt with new impeller with about 12 hours use. Circulating pump is an extra I had about 3 years old that I bought from ebasic power and is a marine unit....... do these have a history of failing? If I get a new one can I use an automotive unit as I am fresh water cooled using anti-freeze?? I would assume that what has happened is the circulating pump failed/broke. anybody see this happen before? TIA TBF

I assume you refilled the AF???? If you're lucky you have a bunch of air in the closed cooling system.

Thanks , I did put some more water in but it did not seem to take very much? I will try and "burp the baby" and take a hose or two off and purge any air out...... Thanks.....

Been busy moving back into my house and replaced all my V-belts today... I filled the heat exchanger and ran the engine for a few minutes to get the thermostat to open, then I was as to put in another gallon of coolant/water..... Runs great once again!!!