Yamaha D150 overheating

[Dim Fiefelmann]

Last weekend put it in and cruised 1/4 mile to the house. When I got there the temp. Alarm when're off. Shut it down and let it cool. 5 minutes after restart same thing.

The water pump was replaced last spring. The tell tale seems a little weak. Pulled port T-stat housing, glory be, no thermostat in there; ditto on starboard . Checked PCV and found a corroded mess.

Just got all new parts and a water pressure gauge.

Question is do I need any lock tight on the housing bolts ? Also do I put gasket sealer on the new gaskets?

Should be on the water by next weekend.

[007]

Don't put any gasket sealer on the new gaskets, you may have to take them off later to clean your thermostats and I wouldn't use lock tite either.

[evansmarine]

Sounds like the popit valve, I would flush from each head thermostat valley through each head until you have good flow coming from popit to make sure no blockage or build up stuck or crap that needs to flow out not to create issues later. Use marine grease on all rubber gaskets and nothing on other paper type. If its fuel injected, the computer need thermostat to keep temps around 143 for proper fuel air mixture and efficiency on economy

[buoy37]

Last weekend put it in and cruised 1/4 mile to the house. When I got there the temp. Alarm when're off. Shut it down and let it cool. 5 minutes after restart same thing.

The water pump was replaced last spring. The tell tale seems a little weak.

I recently had the same problem. Running on the top end would set the alarm off. It has happened twice.

[coachlaw]

I'd follow Evan's advice. Also I had the same situation with my 60 yammy and I had to have my head pulled off and have the engine washed out of sediment. Flushing is good, but some stuff still gets stuck in there. My tell tale was fine, but my alarm went off. I know my engine is different from yours. Also, I've heard nothing wrong with running sans a thermostat in our environment.

[FishNette]

Also, I've heard nothing wrong with running sans a thermostat in our environment.

Huh??? I think there is something wrong with this sentence...

[Ibtsoom]

Yamaha D150 overheating

Means take the thermostat off and run without it.

[007]

Means take the thermostat off and run without it.

That's what he means. You can do that with pre-computer outboards.

[007]

Just to add something.... I had a late 80's model Evinrude 200 that would over heat if I ran too shallow and the only "on the water fix" was to pull the starts and clear any debris from them and that did the trick til I had to do it every trip. Next and last fix was to take out the thermostatsaltogether and had no problems from there on out.