Overheating during cruising but normal under idle

[further]

Hey all, Was pulling the kids on the tube today at about 3200 rpm for about 30 mins or so, stopped to get the kids in the boat and got a high temp alarm…. Temp gauge went up to about 180ish. I shut down and waited a few mins, started back up and idled to our cove at about 1500 rpm’s and temp dropped on its own to normal during the trip. What would cause this? Impeller was changed about 40-50 hours ago-last season.
TIA

 

[Renny76]

I’m dealing with this exact issue right now. There’s been a ton of troubleshooting but I still have to check to see if the risers or manifold are clogged and do a pressure test on intake plumbing to look for cracks.

 

[Donald0039]

Hey all, Was pulling the kids on the tube today at about 3200 rpm for about 30 mins or so, stopped to get the kids in the boat and got a high temp alarm…. Temp gauge went up to about 180ish. I shut down and waited a few mins, started back up and idled to our cove at about 1500 rpm’s and temp dropped on its own to normal during the trip. What would cause this? Impeller was changed about 40-50 hours ago-last season.
TIA

You need to see if it happens again. Could be something as simple as you picked up a plastic bag on the outdrive water intake and when you slowed down the plastic bag got free.

An IR thermometer gun will help you figure out which part is actually overheating. What year? I don't suppose you have a Diacom to read the codes.

 

[further]

You need to see if it happens again. Could be something as simple as you picked up a plastic bag on the outdrive water intake and when you slowed down the plastic bag got free.

An IR thermometer gun will help you figure out which part is actually overheating. What year? I don't suppose you have a Diacom to read the codes.

That sounds like it may be the issue … possible lake weeds clogged up the intake? There are a ton of weeds this year. Manifolds and risers are new as of last year so doubt that’s an issue. Motor is 2004 but new block in 2016 by previous owner. Consistently runs at normal temp. Going out tomorrow again so will see if it happens again.