One exhaust manifold hotter than the other

[rwmoon]

I just bought a boat that had been sitting for two years. We ran it on a hose at idle for a while and everything seemed fine. When we were looking at the motor one of the exhaust manifolds (riser?) was hotter than the other. Is there something that would prevent cooling to one side if there is no RPM's being applied to the motor? Or should I assume that there is an issue and go ahead and take it to the shop? I don't want my first trip to the lake to end shortly after it starts and while my brother-in-law mechanic didn't seem all too concerned it is bothering me. I know the block was replaced before it had been sitting because it was not winterized properly and the new block has ~10 hours on it.

Motor is a mercruiser 4.3L - Boat is a 2001 Crownline 180BR.

 

[alldodge]

Howdy

This is normal for running on a hose. The hose can not supply as much water as needed and water flows the path of least resistance, so one side gets a little more then the other. You can also find similar when running in the water, just not near as much of a difference

 

[tpenfield]

In my experience, I have found that the top of the exhaust elbows are usually within 5-10 degrees F of each other. They should be in the 95-100 F range when the engine is running at idle. . . warm, but you should be able to leave your hand on it. One of them is too hot to touch, then it would be something to look into.

 

[Bondo]

Is there something that would prevent cooling to one side if there is no RPM's being applied to the motor?

Ayuh,.... Welcome Aboard,..... It could be as simple as the side angle of the parkin' lot, or the angle the hull sits on the wagon,...

 

[rwmoon]

So I took it out on the water for the first time and same result, one manifold was cool, so cool i wouldn't say it was warm at all, and one was hot enough that I could only put my hand on it for a few seconds.

What are the possibilities here? Thanks!

 

[alldodge]

Is this an open or closed cool motor?
What's the engine serial number, and is it salt of fresh water?

Need to remove the hoses going to the manifolds and back flush. If the impeller ever came apart look for pieces in the thermostat