Cooling system on 140MC/IO

[Boatbudd]

I have a problem with over heating at idle and have read of several possible problems/solutions; however, I would like to understand how my engine cooling system works. I believe the engine is a Chevy. I know how a car engine works, but need to know the basics of how the water is supplied to the engine cooling system. There is a "tank" on the right side of the engine that is attached to the engine near the thermostat.

 

[NHGuy]

Re: Cooling system on 140MC/IO

Go in to the "Must Have Technical Information" at the top of the Mercruiser forums, and find your motor. Sounds like you have a heat exchanger system to keep outside water out of the block. Look up cooling and find "closed cooling" as opposed to raw water cooling.
Also with poor cooling at idle there's a good chance you just need to redo the outside water pickup impeller in the drive. There is a nice tutorial for it in there. Here's a link to it... http://forums.iboats.com/attachment.php?attachmentid=113737&stc=1&d=1316021371