25 johnson overheating

[jersey devil]

I just purchased a 1994 25 hp johnson and it started to run hot. It is moving alot of water out of the pisser but if i put my hand in the exhaust water it is hot enough to burn your hand. I removed the thermostat and it seems a little bit better but my question is how hot should the water in the exhaust area be? Thanks in advance.

 

[fixmyevinrude]

Re: 25 johnson overheating

I have a 1991 25 hp. Johnson and the water is fairly warm but certainly will not burn you. I wonder if perhaps your water pump impeller is starting to deteriorate.

 

[jersey devil]

Re: 25 johnson overheating

That is what i was wondering. I guess i will drop the lower unit tomorrow and slip in a new impeller.Thanks for the reply. anyone else have any feedback??

 

[eavega]

Re: 25 johnson overheating

You may also need to check for a properly functioning Thermostat. If it is malfunctioning and not opening up, the impeller will move water, but it will not circulate through the water jacket. If you can, pull the t-stat and test it in a pot of hot water. I think the temp it should pop open is about 145 degrees.

-Eric

 

[tashasdaddy]

Re: 25 johnson overheating

the motor was built to run with a thermostat, just put a new one in it. also while the lower is off. remove tstat, and flush the cooling system with a water hose, thru the water tube. the tstat is suppose to open at 140, full open at 160. if you can get an infrared non contact temp guage, check you block temp. i keep one of these in my boat bag. http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=93983

 

[VaGent]

Re: 25 johnson overheating

My 1986 50 hp Johnson runs hot if I am idleing when coming into the dock to load the boat on the trailer. I have to shut it down for a few minutes & let it cool before I can start it up again. The high temperature warning buzzer goes off big time. The pisser seems to be letting a lot of water through it. I was asked what RPM I was idleing at & according to my tach it's around 450-500 in gear. Is that too low? What should it normally be idleing at? It runs great & it never gets hot until I come in to load it on the trailer.

 

[tashasdaddy]

Re: 25 johnson overheating

VaGent, what you just did is called HIJACKING a thread, very rude, you should have started your own thread. sounds like you have an impeller failing. if you can keep you motor running a those rpms, you have a very healthy motor, idle rpms, should be 600 in gear.