Marine: Boating, Sailing, PWC, GPS and Navigation - 228 mercruiser overheated

My 1979 Century 3000 with 305 chevy v8 228 mercruiser alpaha drive overheated yesterday. the water temp went up to around 220. I shut down, checked for obstructions on the intake ports on the outdrive, found none. Then I waited a while until the engine cooled. I started up and at slow speed started to go up the lake and the temp started rising again into the 200 range so I shut down and waited again. I started again and the temp dropped down to 150 and stayed there as if nothing had happened.

Now, I am afraid this will recur again.

Questions: first, any idea why the temp would act as it did?

should I replace the water pump now?

is there an audio alarm available, to supplement the temp gage, which I cant monitor all the time while pulling a skier etc.

thanks

Ed

It could be a stuck thermostat that eventually opened. It can't hurt to replace it.

Check the engine's water pump (not the drive's) for leaks and a loose pulley. Either symptom is a sign that the pump is failing.

Also, pull the boat and run it with ear muffs to make sure you have a good flow of cooling water coming from the outdrive. If you can't remember the last time the drive's impeller was replaced, it's probably time to do that as well.

thanks for the advice, i actually never thought about the engine water pump, i guess i just figured the impeller pushed the water all the way......