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Motor running a little hot

Posted By: TexasPescado

Motor running a little hot - 07/25/16 09:27 PM

I just replaced my impeller and thermostats back in April and all was well till I just took it out last week and noticed it was running a little hot. It's a '96 Merc 150 EFI. It seems to be pumping good. Could this be caused by the high lake water temps? It runs a little hotter at WOT than at idle, but either way the gauge reads a little over half way. I've ordered a poppet valve and am going to replace that too just in case, but otherwise I don't know what else it could be. Any ideas?
Posted By: bronco71

Re: Motor running a little hot - 07/25/16 10:13 PM

just checking..... did you build the dam of sealant between the water pump and exhaust passage?
Posted By: gary purdy

Re: Motor running a little hot - 07/25/16 10:51 PM

What do you mean by a little hot. Many times you can actually see better WOT water pressure by closing off the top 2 water intake ports on both sides of the lower unit. I use Permatex black RTV. The warmer lake temps definitely have an effect on everything.
Posted By: TexasPescado

Re: Motor running a little hot - 07/26/16 12:22 AM

Originally Posted By: bronco71
just checking..... did you build the dam of sealant between the water pump and exhaust passage?


No, I did not see that as part of the replacement procedures on any of the instructions I saw for my motor.
Posted By: TexasPescado

Re: Motor running a little hot - 07/26/16 12:24 AM

Originally Posted By: gary purdy
What do you mean by a little hot. Many times you can actually see better WOT water pressure by closing off the top 2 water intake ports on both sides of the lower unit. I use Permatex black RTV. The warmer lake temps definitely have an effect on everything.


The temp gauge is at about 5/8 at idle and 3/4 at WOT.
Posted By: TLW

Re: Motor running a little hot - 07/26/16 10:45 AM

sounds like ya might be a little antsy...

generic temp gauges just give ya something for a "guess" at being hot or cold.. a temp gun will tell ya at what temps are (only true way of knowin' what actual temps are) and can be compared to where tha gauge is reading.. other than that as long as tha over temp sensor and buzzer are workin' should be good...

thats why "temp gauges" are usually an option (or use ta be).... probably used as a "sellin' point" nowdays...
Posted By: TexasPescado

Re: Motor running a little hot - 07/27/16 09:05 PM

Originally Posted By: TLW
sounds like ya might be a little antsy...


You're probably right! Just want to make sure I don't blow it up!...I don't have a warehouse full of powerheads, or a warehouse full of money!

I'm going to change that poppet valve and see if it gets any better. Probably should have done it at the same time I did the impeller, but better late than never.
Posted By: dimitri

Re: Motor running a little hot - 07/29/16 08:07 AM

my 250 pro xs is running around 8 degrees higher temp now that the water is damn near 90 degrees. in april dtats opened around 137. now it's around 145.
Posted By: Angler's Marine

Re: Motor running a little hot - 07/30/16 05:09 AM

With the lake water temps as hot as they are right now your motor will definitely run hotter somewhere around
10 degrees hotter. If no alarm you should be ok.
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