Overheat at idle after impeller change

[mrichmond]

My '84 V6 150 Evinrude is overheating after changing the impeller. Any suggestions on what the cause is? I do not have a water pressure guage to check the flow but there is water coming out of the pee hole. Any help would be appreciated. Thanks in advance.

 

[OBJ]

Re: Overheat at idle after impeller change

Question(s)...when reassembling, are you sure you got the water tube in the impeller housing outlet? Did you remember to put the impeller key in? Got a good pee stream?<br /><br />Or...is one head or both heads overheating? Each head has a t-stat which means one head could overheat if that t-stat sticks closed. Put the muffs on and check to see if one or the other head is causing the problem. If its' been a while since the t-stats were serviced, might consider replacing both. If both heads overheat and you have a good pee stream, check t-stats.

 

[Dhadley]

Re: Overheat at idle after impeller change

And the deflectors in the water jacket.<br /><br />If all you really changed was the impeller, you might think about replacing the housing liner and wear plate.

 

[68wetboat]

Re: Overheat at idle after impeller change

regarding the t-stats.....how do I check if my 1968 Johnson 40hp has them....I have the service manual...but am not finding t-stat info in it...any help?

 

[mrichmond]

Re: Overheat at idle after impeller change

It seems that both cylinder banks are getting hot and only at idle. The water tube seems to be seated correctly and it ran fine wide open for two hours after the change. It only overheats at idle. When i replaced the impeller it was a full kit (included the housing and wear plate). When the engine is first cranked you can feel the pee stream go cold then warm as the thermostats open and close. Where do I go from here? I have read other posts about sucking exhaust gase back through. I am pulling the lower unit tonight and need some direction on which way to go.

 

[Dhadley]

Re: Overheat at idle after impeller change

I'd look at the deflectors if youre convinced the T-stats are working.

 

[mrichmond]

Re: Overheat at idle after impeller change

I have the manual, but I can't find anything about the water deflectors. Where are they? Thanks.

 

[Dhadley]

Re: Overheat at idle after impeller change

In the water passage around the cylinders behind the heads. They are small pieces of rubber. As they get old they swell and can actually restrict water flow.<br /><br />Since the motor's been hot it's probably a good idea to change the head gaskets anyway. The part number for the deflectors is 322411. You'll need 6.

 

[mrichmond]

Re: Overheat at idle after impeller change

Thanks for all your help. Will post results after I perform the post mortem.

 

[Dhadley]

Re: Overheat at idle after impeller change

Cool! Keep us up to date!