Johnson 25 - no cooling at idle or low RPM

F

Fadrowski

Cadet
Joined
Jun 24, 2003
Messages
9
I own a Johnson 25 model #J25TELCEM and when it idles or is running at low RMP no water comes out the water pump exit tube. It looks like steam is coming out instead of water. When I increase the RPM a little, then water starts coming out and it is initially super hot (almost boiling hot). When I run it at normal use RPM's, the water stream is steady and the water coming out is luke warm.<br />Does this mean something is wrong with the water pump or is this normal. I don't want to overheat the engine if this is not normal.<br />Thanks,<br />Bill
 
F

Fouled Plug

Ensign
Joined
Jun 29, 2001
Messages
935
Re: Johnson 25 - no cooling at idle or low RPM

No, this is not normal. When was the impeller last replaced? Sounds like its time for a new one.
 
X

Xcusme

Commander
Joined
Apr 21, 2003
Messages
2,888
Re: Johnson 25 - no cooling at idle or low RPM

Bill, Fouled Plug is right, it's time for a new pump/impeller. If you're seeing steam, the motor is already overheating. The powerhead is approaching 212 degrees to produce steam. It's not a bad idea to check and or replace the thermostat too. Sometimes, debris will be backed up behind the thermostat too, holding it open.
 
M

Mucka29

Petty Officer 3rd Class
Joined
Aug 31, 2003
Messages
87
Re: Johnson 25 - no cooling at idle or low RPM

hey!<br /> i had the same problim with a 25hp rude, check your head gasket
 
W

werdna

Seaman
Joined
Sep 9, 2003
Messages
57
Re: Johnson 25 - no cooling at idle or low RPM

i would say scrap your thermostat. both of my motors have come standard without a thermostat, as in Aust (i dont know what the weather is like in your part of the world) the motor is a nice warm temp to start with, so there's really no need to have a thermostat in it. i asked my mechanic if i should have one and he said no...<br />Andrew
 
F

Fadrowski

Cadet
Joined
Jun 24, 2003
Messages
9
Re: Johnson 25 - no cooling at idle or low RPM

Thanks for the advice.<br />Had the water pump impellar changed and it cools properly now, with the steady stream of water at idle, low RMP's, and at running speed
 
G

G DANE

Commander
Joined
Nov 24, 2001
Messages
2,476
Re: Johnson 25 - no cooling at idle or low RPM

Not to start arguing, but I dont think ANY of these motors came out without thermostat.<br /><br />They run much better with it in, warms up better and stays at a consistant running temparature. Leave it in.
 
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