Engine Running a Little Hotter.....

[capecodder116]

260 Mercruiser, closed cooling system. Was out yesterday and noticed the temp gauge was running a bit higher than normal at 3K R.P.M. I'm ruling out the thermostat wondering if it's time to change the exhaust elbows..?? Anyone know what the life is on the elbows..?? Also about the exhaust manifolds....can anyone confirm only anti-freeze circulates thru them. Thanks....

 

[Bt Doctur]

Heat exchanger getting clogged, risers getting scaled up (4-6 years) .As far as the manifolds go we need a pic of the hoses. Most full systems include the manifold with a engine mounted pump. If you have 2 hoses on the manifold (top and bottom) there AF cooled .and one hose on the riser for raw water exit

 

[stonyloam]

With a closed cooling system the outdrive water pump impeller is critical, so that should be the number one suspect. The thermostat or exchanger could be a problem, but it is far more likely to be the impeller. If it has not been changed in the last three years, change it.

 

[capecodder116]

Thanks for the responses....!!

Bt Doctur; I'll check the hoses on the manifolds. So if manifolds are AF cooled no need to mess with them? What is the procedure for checking/unclogging the heat exchanger..?? I see there are removable end caps. About the elbows, if I put infra red temp gun on them, any idea what temp should be...?

​Stonyloam; replace the raw water impeller every other year. Was done 2016 season.

 

[Bt Doctur]

So if manifolds are AF cooled no need to mess with them

I never said that, sometimes they do force hot exaust gas into the cooling system from pinholes in the casting.
If the boat and motor are whats listed the impeller will have a hard time cooling everything in a full system.
Put a IR on them and tells US what the readings are

 

[Alumarine]

When you say a little higher than normal, what is it reading?
What was it reading prior?

 

[tpenfield]

Exhaust bellows will probably not affect the issue. If you boat in the salt, then I would check the condition of the heat exchanger. Any marine life growing inside the outdrive water duct?