Mercruiser 170 trouble

[cfelton]

Took the V out for the first time this year since I did the gimble reboot thing and solving my cooling issue last summer. We ran it up the Chowan river about 15 miles, ran 165 degrees, all ran perfect. Fished part of the day, caught white perch two at the time, grand daughter skunked us all. Hung out at a nice secluded beach with friends until late in the afternoon, had a blast. On the way back, noticed the temp started climbing up. Slowed down, kept climbing to about 180 so I cut it off. Raised the cover and steam bellowed out everywhere, thought I blew a hose. About this time I see the Coast Guard throw the blue lights on and head my way. Here I am trying to see what happened and they want to check me from one end to the other. All my stuff was in order and they were nice enough to tow us back to 1/2 mile from the ramp, paddled the rest of the way! Found one of the 5/16 bolts in the thermostat housing pulled the threads out of the exhaust manifold and dumped the coolant. Drilled it and tapped it out to 3/8 and put it back on with a new gasket. Seems to be ok now, haven't taken it out since. Hopefully it was just a weak threaded hole in the aluminum manifold.