150 Merc Offshore, Over heating problem, Plz Help!!!

[Ant-Knee]

Hello All,

I have a 98 merc 150 outboard 2-stroke motor on my boat,


I have changed the impeller, Stats, Poppet valve, Temp Sensors Both..
But the motor still seems to over heat ( 230 - 240 Degrees ).. But when at idle the temp is normal..
Only seems to heat up one i get going.. The faster I go, The hotter she gets.. If I slow down the temp comes down..

The hole cooling system is new, What else would cause this???


Thanks,

Ant...

 

[schematic]

Re: 150 Merc Offshore, Over heating problem, Plz Help!!!

how are you measuring the temp?
what RPM are you getting at WOT?

 

[Ant-Knee]

Re: 150 Merc Offshore, Over heating problem, Plz Help!!!

I have the warning buzzer, and a temp gauge, ( Both New )
The gauge gets up to 240 degrees then the alarm sounds,
Temp comes right back down once I ease off the throttle..

At idle temp is at 150 - 160 never gets any higher at idle. Bump the throttle up to about 2000 rpm temp starts to rise right away.
really starts to get hot at 2500 - 3500 rpm.

Thanks Ant..

 

[Faztbullet]

Re: 150 Merc Offshore, Over heating problem, Plz Help!!!

Sounds like the poppet is slightly stuck open or the seat is missing..Could be salt build up in block blocking /restricting water passages...has it ever run correctly or did problem just start after the part replacements?

 

[Ant-Knee]

Re: 150 Merc Offshore, Over heating problem, Plz Help!!!

It was over heating before all new parts...
Is there a way I could flush the system?

Thanks,
Ant...