murcruiser 488 190hp 3.7

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chadharrop

Cadet
Joined
Mar 26, 2011
Messages
9
I am thinking that i might have to rebild motor over heated and now is knocking. How big of a job is this ? i have the out drive off and i am putting a new water pump in today. i will be starting this boat to today to see if it still knocks when is being cooled the right . i have been told this motor will make noise if not cooled right and fast. i did not overheat it to bad. What are my best options?
 
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guyaverage

Petty Officer 2nd Class
Joined
Aug 4, 2008
Messages
101
Re: murcruiser 488 190hp 3.7

Any overheat on this engine is a bad one. At a minimum you are probably going to need a new head gasket. Monitor your oil and antifreeze levels closely after you start it.

What was your oil pressure like before and after it started knocking? Does it sound like a rod knock? Or a lifter? Not too sure the overheat and knocking sound are related, you probably have two different issues going on.
 
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stonyloam

Vice Admiral
Joined
Mar 13, 2009
Messages
5,832
Re: murcruiser 488 190hp 3.7

chadharrop said:
I am thinking that i might have to rebild motor over heated and now is knocking.
Click to expand...

Yeah 470s don't like to be overheated. I would think a lower end knock (rod or crank) would more likely result from lack of oil rather than overheating. I would look to the top end, especially in a 470. Get it running on muffs and do a compression check and a cooling system pressure test. That will tell you a lot. You can borrow the tools for both tests from Autozone (free). Good luck.
 
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