High speed Overheating

[sibnai1]

so, I did the outdrive impeller a couple weeks ago and used my baby approx. 6 times since then and she ran really really well, however I took her out today and she was overheating at high speeds, the gauge climbed past 200 (was probably @ 225) before I saw it so I shut her down and let her cool off, both risers were extremely hot to the touch so I opened up the sunpad area and the engine compartment and let her cool off. Once she was cool I headed back in and realized that at low speed she was not running hot she can idle infinitely without overheating. I'm guessing blockage as there was a lot of milfoil in the water on my way out, I'm guessing I'll have to look at the thermostat, should I start pulling the risers possibly because of other than milfoil blockage?? Maybe the circulation pump on the engine?? Can I back flush and blow out blockages by using the engine flush spigot on the transom by the swim platform area?? Thermostat housing (cholesterol and plac reducing the water passages)issue??? I was able to stay out just putting around and enjoying the weather so all was not lost but I want my baby purring again. She is raw water cooled, bah humbug!!! Thanks in advance for any and all advice and suggestions!!

 

[Bt Doctur]

Impeller is the first thing to have checked/replaced. A severe overheat will destroy the plastic coupling tube at the pump base.
Not to mention the chance of blowing the head gaskets. A compression test should be next.

 

[sibnai1]

Impeller is the first thing to have checked/replaced. A severe overheat will destroy the plastic coupling tube at the pump base.
Not to mention the chance of blowing the head gaskets. A compression test should be next.

Thanks for the advise BT Doctur I'll give it a look!!