Overheating motor

[spinalcracker]

I have a 1968 Mercruiser 120 with a pre alpha outdrive. I replaced all the bellows, shift cable and outdrive this summer. I have a temp guage that is yellow then green then red. When I start the engine muffs/lake the temp will raise up to the line between the green and red. If I run the engine at 3500rpm for a minute or 2 the guage will be in the red, then I go back to idle and it will return to line between green and red in a min or 2 of idle. I have a new inpeller when I redid the outdrive and just replaced the thermostat thinking that was the problem. What else do I need to check/change or does this motor run this hot all the time?? Water is coming out of the prop when the engine is running so I think water is circulating through the motor.

 

[spinalcracker]

Re: Overheating motor and shift cable questions

Re: Overheating motor and shift cable questions

could this be from a kinky intake hose maybe? Still doesn't seem right since I have good water pressure to the motor.

 

[Fishermark]

Re: Overheating motor and shift cable questions

Re: Overheating motor and shift cable questions

You will be better off to edit this post to deal with only one question - then start another post for the other problem, as it may get confusing....

On the shift problem, you need to do a test of the shift spool It is a simple test. Here is a video I took of doing the test on my outdrive. That turned out to be the problem on mine.

 

[Don S]

Re: Overheating motor and shift cable questions

Re: Overheating motor and shift cable questions

Have you checked the exhaust elbow to see if it's plugged up?
I would also get one of those IR temp guns and see what your engine is actually running at. Take the temp right at the temp sender and compare the digital readout to your green/red mark on the gauge. Be rough to fix a temp problem when you don't really have one and the gauge is wrong. Don't forget, that gauge is 40+ years old.

 

[spinalcracker]

Re: Overheating motor and shift cable questions

Re: Overheating motor and shift cable questions

thanks Don will try that tonight