Older Honda 75 4 stroke issues plpease help

[Deldolfan]

I have an older carbureted 4 stroke Honda 75 on the back of a Aqua patio pontoon. Engine has been flawless for as long as we have owned it. Sips fuel and is so quiet. Did have to replace the impeller last year and that's all. This year brother ran it up on a sand bar and tried to power his way out. Said engine did overheat. Eventually got it off and said everything was fine after that. Used it everyday until a few days later he was out again and the engine would run at WOT for about 4 minutes and then die. Evidently anything over idle would do the same. I'm the mechanic of the family and am away from the boat now. He did pull the top cover and noticed the oil was the color of sand so may have a water issue. Will have him check the fuel tank vent, the crankcase vent, and replace the fuel filter. He will send me a picture of the oil and also let me know if it is above the fill level (maybe condensation or another issue). Am I on the right page or is there something else I should have him look for before I get down in a few weeks. Thanks for your help!

 

[Deldolfan]

Update: Brother pulled the dip stick and it was covered with a light tan slime. He said it smelled like gas. But looking at the picture he sent, you could see the caramel colored oil at the bottom an inch before the slime starts so I think it's mostly water contamination. He also said this slime was evident on the inside of the filler cap. Said the oil level was at least an inch above the fill mark. I don't have complete confidence that the guy that services the engine when the boat is pulled in the fall is actually changing the oil and gas filter as he bills so not sure if this is a long developing issue or something recent. I don't know if this points to a different direction but I am now concerned that it may be a head gasket.