3.0 GLPJ overheat

[tobywaz]

Hi,
I have a 2008 3.0 GLPJ engine that is showing symptoms of what I can understand to be a high speed overheat scenario. It ran great last year and when I took it out the other day my temp gauge spiked to ~210 degrees before I throttle from 4,000 rpm's down to idle speed. I thought the thermostat was stuck and motored back home. I pulled the water pump impeller and replaced with brand new one. Old impeller was not missing any vanes. I ran it again and it overheated again. I replaced the thermostat and tried yet again with same overheat. I pulled the thermostat and it still overheated. This is a freshwater boat that I have owned since buying the boat new. My question is does my exhaust riser or exhaust system have a "flapper" in it? It seems to me I am not getting enough water flow out of the boat to cool the engine. Is it typical that the bottom of the exhaust pipe that has the what I will call screen in it or plate with drilled holes to collect debri and cause this type of issue. Any help would be appreciated.
Thanks

 

[vwbugman69]

Does it cool back down when not on plane?

 

[tobywaz]

No it overheated will at the dock regardless of what rpm I run it at. I am thinking my exhaust pipe might be clogged.

 

[tobywaz]

Got it back from the shop, exhaust elbow was plugged with small rust debri. Runs great now at 160 degrees. Will keep an eye on it in the future for possible replacement.