overheating Johnson

[Green Willie]

I am frustrated to the hilt. I haven't had a chance to get my boat out this year yet (back surgery), I fired it up today (Johnson 90 horse with earmuffs going full blast) and it overheated after about 5 minutes. This is the third year in a row for it to do this. I back washed the cooling systems in the event that little creepy crawler (spiders) had set up inside (had that happen before) and all of the tell tales/ports were squirting full strength. Does anyone have any idea why this is happening. Every time, I take it in to the shop, they tank test it for 30 minutes without a problem and it runs great for me in T-Bay. So, what gives? A few years ago, the motor was running rough, so I took it in, and I was told that it was running too cold and they put higher temperature thermostats in the system. It runs great now, but do you think that heat sensor is off now, or is there a connection? Looking for thoughts, experience?

[Lou]

I am frustrated to the hilt. I haven't had a chance to get my boat out this year yet (back surgery), I fired it up today (Johnson 90 horse with earmuffs going full blast) and it overheated after about 5 minutes. This is the third year in a row for it to do this. I back washed the cooling systems in the event that little creepy crawler (spiders) had set up inside (had that happen before) and all of the tell tales/ports were squirting full strength. Does anyone have any idea why this is happening. Every time, I take it in to the shop, they tank test it for 30 minutes without a problem and it runs great for me in T-Bay. So, what gives? A few years ago, the motor was running rough, so I took it in, and I was told that it was running too cold and they put higher temperature thermostats in the system. It runs great now, but do you think that heat sensor is off now, or is there a connection? Looking for thoughts, experience?
I think a lot of motor will over heat with muffs. A run in the river
would give you a better test. It could be a sensor.
If it pee's and doesn't boog down, I wouldn't think, it would hurt/
Have you checked the pump? How log ago was it changed?

[snit]

I agree..."muffs" are for idle only is what I've always been told.

[Green Willie]

I think a lot of motor will over heat with muffs. A run in the river
would give you a better test. It could be a sensor.
If it pee's and doesn't boog down, I wouldn't think, it would hurt/
Have you checked the pump? How log ago was it changed?

Thank you for the response. This motor is about 10 years old, but has few hours, and has been serviced several times. It was running rough, but Greg, at Greg's Marine Service in Garibaldi, said that the factory thermostats were too cold for our water. So they changed them out, and it fixed the problem.

It has had the overheat alarm go off, and I took it to Greg, they tank tested it for 30 minutes with no problems. I'm just nervous about dropping it in T-Bay.

The tell-tale is peeing full strength, and all of the water ports squirt normally. I also backwashed the system with water, and back blew the system with my air compressor.

Mike

[budnate]

my OMC V-4 motor has done that twice with the flusher on it in the past, makes you cringe...there should be more than enough water than just laying in the lake on the hose, I think they trap air somehow from the force of water up in there somehow and then the stats dont have any water to operate from...then bam the buzzing starts...I have thought about mine many of hours as to why?.. only thing I can think of.

a old mechanic years ago showed me how to drill a itty bitty hole at the base of the thermostats to bleed air just in case, I now do it on any stat I install boat or car...best insurnace policy a guy can do. and it dont affect how things run temp wise.

B.