Running hot

[Undead357]

I have had my boat docked at a marina for 8 days without running it while i was on vacation.I took it out and it started running hot,i can idle it down some and it runs normal temp but if idle too long it runs hot in a no wake zone.I brought it home powerwashed it down and put in a new thermostate,idled it for thirty mins. and no prob.is there anything else i should check before i launch it? The boat is an 85 contender I/O with a 5.7 litre chevy motor. mercruiser outdrive.Any help would be greatly appreciated thanks...

 

[Chris]

When is the last time you changed the impeller?

From my experience, a worn impeller is the most common cause of cooling issues.

-Chris

 

[dave]

when you run an engine at home on the hose the water pressure from the hose is enough to keep it from overheating even with a bad impeller in the drive, chris is right check the water pump in the drive.

 

[Fun Times]

When it comes to a overheat situation you'll always want to start with a new rubber impeller in most cases, Then work your way up to the engine.

You may also need a new impeller housing as well.

Good luck with it.

 

[Fun Times]

Also if you find any rubber impeller blades missing you will want to try to find them upstream in the cooling system, If not then they could cause a blockage in the water flow to the engine/oil cooler.

 

[Undead357]

Thanks for the info.I did check the impeller it looked good.I am going to get a water pump kit this winter to have just in case.I took it out and it ran at normal temp,must have been the thermostat...

 

[Chris]

That sounds like a good plan.

Impellars are actually supposed to be a regular maintenance item, but most people unfortunately ignore them until they start running hot.

Make sure you install it running in the correct direction and always make sure you have lots of water when you run it on a hose. If they are run dry or without sufficient water, they quickly burn up and then you're back to square one all over again.

Let us know how you make out.

-Chris

 

[Undead357]

Thanks Chris i am ordering two kits and taking your advice,i'm going to change it when i do the winterizing. That will be a good habit to get into and its always good to have a spare in the garage !!!