murcruiser 488 190hp 3.7

[chadharrop]

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?

 

[guyaverage]

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.

 

[stonyloam]

Re: murcruiser 488 190hp 3.7

I am thinking that i might have to rebild motor over heated and now is knocking.

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.