Need help! I’m stuck and boat overheating can’t figure out why

[Iwantacarver]

Carver 36 twin 350 gas engines
Keeps overheating wheneve the boat is sitting ag the dock only


When we drive it it doesn’t overheat

Any ideas???

[Cooler]

Many times a weak impeller will not be able to run enough water at idle speeds. Try goosing the engine a few times, while in neutral, to see if you can improve water flow and reduce temp. How high is the temp gauge getting? You may also want to check t-stats. If they are the old bowl style, they may be malfunctioning due to rust deposits. er

[Iwantacarver]

It revs perfect but in idle at rev will still overheat. It’s only when you slow down

[bud37]

A couple questions to clarify...
Do the engines have antifreeze in them or just raw water from the lake ?
Have you checked your impellers?
Did this just start for both engines ?

So to be clear....when the boat is not moving both engines will get hot no matter what rpm they are at?

This will help to sort this out.

[Iwantacarver]

Yes the engines have antifreeze in them and water they are cooled by both.

It happens at any rpm as long as it’s sitting at the dock or going less than 5MPh

[Dustin07]

check thermostats, check the strainers. could a clogged strainer possibly struggle to get enough cool water through the system when sitting idle, but force more water through while under way? I like the above suggestion to check impellers too.

How hot is it getting? what are you doing when you see it overheating to get it back down? where we live, I have to idle out at about 5 knots for nearly 20 minutes just to get out of the harbor so I'd be in serious trouble if I was over heating at slow speeds.

Shoot the elbows with a IR gun to get the temp on them as well see if it matches the gauge. have you felt them to see if they are warm to the touch when the gauge says they are?

for 2 years (on 2 different boats) I have fought cooling issues (although opposite direction, never overheated at idle) so I feel for you. I have done a lot of trouble shooting on this issue over the last 2 years.

[km1125]

First, when referring to "350 gas engines", that could either mean 350CI or 350HP, so it's a good idea to clarify that so others. Based on the size of the boat, I'm guessing these are 350HP Crusaders, which are 454 CI.

I also wonder what the condition and age of the impellers are.

Do you have strainers? If so, check to make sure you're not sucking air in where the cap is. When you're cruising, water is being pushed up into the raw water pump due to the scoops, but when you're stationary the raw water pump has to suck the water up and if there are any air leaks it will suck in air too, reducing the amount of water it's able to pull in.

[Iwantacarver]

It’s 350 5.7 engines
Gas engines 320HP

[Tireless]

Not sure how you made out?

It sounds like your engines are close cooled. I would like to know what the water volume is coming out of the exhaust to ensure you have enough going though the system or is there a circulation issue.

In addition to the things mentioned, like impellers, strainers and whether there is a blockage at the intake, what is your coolent levels in your reservoir. Could you be low in coolent (anti freeze).

Greg

[Iwantacarver]

It’s perfect the coolant level I have bled the system too.