Boat overheating at full throttle

[jec3u]

My boat is over heating at full throttle but not at idle and I'm not sure whats wrong. I just got the boat in April. The guy I bought it from didn't run for a year and half. I changed the impellar and the t stat but it still does it. It did have water in the oil when I first got. I changed it out but not sure if I got it all. Im just not sure where to go from here. Any help would be great.

 

[Bondo]

Re: Boat overheating at full throttle

Ayuh,... Welcome Aboard,...
What are We workin' on,..?? 3.0l,..?? 350,..??

 

[jec3u]

Re: Boat overheating at full throttle

Thank you. Its a 3.0 I believe. 4 cylinder

 

[jtyree]

Re: Boat overheating at full throttle

Thank you. Its a 3.0 I believe. 4 cylinder

This happened to me and after much headaches found some old impeller pieces wedged into the upper half of the outdrive water jacket. I had pulled the water hose coming from the outdrive and it seemed to be flowing fine but I actually found a technical service bulletin in the manuals section that had an output volume and mine was only about half. If you pull the outdrive and look back into the water port all the way in the back, that is where my problem was. Hope this helps.

 

[Don S]

Re: Boat overheating at full throttle

You really need to find out for sure. Engine serial number will help. Year and a picture may help also.

 

[jec3u]

Re: Boat overheating at full throttle

Alright I will check that this afternoon. The old impellar was missing alot of pieces. The boat itself is a 90 model Im not sure about the engine but the serial number is 6209407 and the model number is mcm 140. 181cid

 

[Don S]

Re: Boat overheating at full throttle

Your engine is a 1982 140.

The old impellar was missing alot of pieces.

Those missing pieces may be why it's overheating. They could be stuck in the exhaust elbow and preventing water flow.

One other thing about impellers that are in pieces, if they were destroyed due to running without water, the chances are high that the pump housing and base were melted or damaged. If this happens the pump will not seal, and will suck air and overheat.

 

[jec3u]

Re: Boat overheating at full throttle

Alright I started checking some things and the hose from the outdrive to the t stat housing was being blocked by pieces of the impellar. I cleaned all of that out and after that I turned the water on and the water flowed good. I'm about to take it out and find out if that was the problem.