Overheating problem on Volvo Penta 4.3L carb motor with less than 100 hours on it

Claytorman

Recruit
Joined
Aug 16, 2011
Messages
1
I really need some help on this one. My boat is a 2008 with the 4.3L Volvo Penta/SX drive with carb. I went out today and the engine overheated. The temp alarm went off and when I finally figured out that it wasn't my depth finder freaking out, the temperature gage was at 225F. Luckily, I was only 100ft from the loading ramp. I let it cool off a while and loaded it on the trailer. I got home and found that the blue cap to the flush port was undone. I flush the lake water out after every trip, I swear that I remember putting it back on, but maybe I didn't get it tight. I read in the manual that this can cause air to get in the system, thought my problem was solved. Ran it with the water hose connected and it heated up again. I had a spare impeller, so I put that on. I found one blade had a chunk missing, luckily it was lying in the housing. But finding the blade chunk makes me think that there was no water flow, otherwise it seems like it would have been inside the engine. Anyway, new impeller still did not solve the problem. It is still getting hot.

Should I try a new thermostat next? The boat only has 98 hours on it. If I really had zero waterflow for a time, could this have damaged the thermostat. The engine water pump seems fine, no leaks from it that I can detect.

Before I replace the thermostat, could I remove the hose going to it and see if I am getting good water flow?

Thanks
 

Maclin

Admiral
Joined
May 27, 2007
Messages
6,761
Re: Overheating problem on Volvo Penta 4.3L carb motor with less than 100 hours on it

It is probably not the thermostat, so you are on the right track thinking to check the raw water flow first. Maybe the impeller install did not go as well as it could have.

Along the lines of your findings after the overheat, there could be a problem with the fitting that the cap fits on leaking due to cracks, or the cap itself may be cracked and acts like it is going on but then expands later and pops off.
 
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