Honda 150 heat alarm revisited

[Thanh]

Hi all
New to the site,
I got a used 2008, mounted it and ran it. Heat alarm goes off at high throttle. Call mechanic and he says new impeller and housing so got that done. Test run and no change. Then did internet research and change 4 temp sensors (1 was pretty caked), checked t-stat with hot water (all good). Test again and no change. Opened the side and check the high pressure relief and ran a garden hose in the T-stat opening with the lower unit off to back flush. Test run and same thing. Anything else?? I did not change t-stat or relief valve assy. Should I? My next move would be taking off the lower unit and check the connect of the water tube and up, remove all hoses and check for debris stuck. Forgot to mention my piss indicator is strong running. Shops are a month+ out for appt.

Can someone explain how the pressure relief travels? I have an idea of how it works. The reason I ask is the picture on Boats.net has the part spring down and pop upward but the actual way it is placed is with the spring up and pops downward. With spring pretty firm, I can not figure that it would create enough water pressure to open the relief valve.

Thanks in advance
Thanh

 

[johnnygjr]

have you run a compression test on cylinders, after running,check plugs for possible water droplets,sign of gasket issues,checking water tube good idea along with backflush. IS engine really running hot? place hand in telltale,should be able to keep hand in stream indefinitely, Place hand on head for a six second count,if no burn it's okay Infrared thermometer can be used instead of human factor. Not sure of honda relief valve system but john/rude poppet system works at high rpms to provide extra cooling at higher speeds. Check your water intake screens for debris

 

[Thanh]

I got it used. The guy is a backyard mechanic. He check Compression and I took his word. Water on the piss stay cool, never gets hot. I read somewhere on this sight that it Ts off before the head or something. Intake screen clean. Just got a Infrared gun and will confirm if running hot. Not sure if I need to reset ECM.