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Question RE: Mercruiser 470?

S

Shawn Rowden

New member
Hello, we are looking into buying a boat with a I/O mercruiser 470. They said it was a "closed loop" engine and ran it for a few minutes without water to it. They told me over the phone that it was okay due to the closed loop engine. My question is, can this really okay? I'm a newbie to the I/O boat engines but I know with the outboard and inboard we have owned you always needed the muffs or a fake a lake set up. Thanks for your help!
 
With that setup, running without any water won't hurt the engine in terms of overheating, HOWEVER, it is very likely that the raw water pump impeller is damaged. Not designed to run dry. Damage can occur in less that 30 seconds of running dry. You won't notice the damage until the boat is in the water and running for more than a few mins. Runng the "stack" dry, i.e., no cooling water in the exhaust path will cause damage to the rubber parts which are designed to be wet at all times and never see more that 150 degree temperature (water cooling of the exhaust by direct injection of water into the exhaust stream).

Take BONDO's advice. Pass on this boat. At best, 470s are problamatic.
 
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