Mercruiser 140 Overheating

[Uncle Dave]

Greetings All,<br /><br /> After a lengthy refurb of the boat, I got it to the lake this weekend. It runs cool (160) at any speed below 2,000. Go over and it overheats. And heats fast if at 4,100. I did not allow it to exceed 200.<br />During refurb I would crank occasonaly and run for 5 to 10 minutes with no overheating.<br />The outdrive was rebuilt just before I got the boat and I assume the lower pump was replaced.<br />The unit is a 1986 or so and has been in salt water.<br />The out side of engine and manifolds, etc all look like new.<br />Any ideas of where to start frist?<br />Thanks,<br />Uncle Dave

 

[xltier]

Re: Mercruiser 140 Overheating

when u would crank it over and run it,i assume u had water going thru it??

 

[Haut Medoc]

Re: Mercruiser 140 Overheating

Fresh wc or raw water cooled? The pump impeller should have been replaced, but you don't know for sure. If you're running 160 with rwc I would say you have some stuff to look at. Again fwc or rwc?

 

[Uncle Dave]

Re: Mercruiser 140 Overheating

As far as I could tell it was exhausting water. Also as stated it would run at 160 degrees if kept at 2000 or less rpm. But go on plane and it would heat up.<br />There seemed to be water just not enough?

 

[Haut Medoc]

Re: Mercruiser 140 Overheating

You still haven't answered any of the above questions..........................

 

[Uncle Dave]

Re: Mercruiser 140 Overheating

It is raw water cooled and has been in salt a limited amount.

 

[Haut Medoc]

Re: Mercruiser 140 Overheating

Did you have muffs on?