1991 force 150hp outboard overheating

[deltafish]

I have a 1991 150hp outboard that is overheating. I am a beginner outboard mechanic. I changed the thermostat, water pump and impeller. It seems to me like the water is not making it to the top of engine. Also I noticed at idle the top 2 exhaust ports sometimes stop blowing any water out at all and then it overheats or at least sets off alarm. Does anyone have any ideas? Please.

 

[scout-j-m]

When you replaced the impeller do you make sure the key was installed which connects it to the drive shaft?

 

[Stitz80]

I recently replaced my water pump and it was doing the same thing and I check it again and the copper tube wasn't connected to the pump properly. Once I put the tube it worked fine

 

[Frank Acampora]

Did you replace both gaskets on the stainless plate when you replaced the impeller? Also, sometimes the engine gets sand in the water passages. You may need to try and blow it out and finally you may need to actually remove the head and clear the water jacket around the cylinders.

 

[jerryjerry05]

No Title

The owner complained of a buzzer going off????
He bought it used and the seller said they hardly used the pontoon.
Towed in all 3 times he used it.
Get yourself a heat gun.Under$20
Start it and check for hot spots.

 

[deltafish]

I am tearing it down again. I will try to back flush from thermostat housing,clean and clear water tube, double check impeller to make sure i have in right direction. changing thermostat again in case 1st one defective. I dont know what else I can do anything else probably out of my wheel house and skill level.

 

[HotTommy]

Check the compression. It can tell you if you have a problem like a blown head gasket or a failed piston ring. My 150 started overheating after a ring failed and debris started rubbing against the cylinder wall with each cycle of the piston.