Merc 1999 40hp 4 stroke, over heating?

waggler

Recruit
Joined
Dec 27, 2013
Messages
1
This problem started out as intermittent but now after running a few minutes it kicks into protection mode, at this point it appears to be pissing just fine and the water is just warm. If I hit the kill switch just for a second then back to run it resets something and the motor runs normally for a 5-30 seconds, then back into protection mode, repeat the kill switch procedure and runs fine again. This process can be repeated several times but the duration time of it running normal decreases each time. Finally you get a mixture of steam and water out of the pisser mixed with motor oil. That last about 3 seconds followed by a puff of steam. Then I shut the motor down. This progressed to this condition over a few days.
There is no water in the oil, compression is fine, took out the thermostat it appears to be fine, pulled the power head off and inspected the lower exhaust housing and replace the two gaskets, and it still does it. It must be somewhere in the powerhead?? I'm open to any suggestions.
 
Top