94 Johnson Thermostat

Reply

  #1  
Old 03-31-05, 04:11 PM
FredP
Visiting Guest
Posts: n/a
94 Johnson Thermostat

I tried to sell my boat that has a 90HP 94 Johnson engine, and on the day I "sold" it the engine cooling horn came on., overheating but good flow out of the tell tale, so I was told by the dealer it was a sticky thermostat. Calling that bad luck.
Now I am trying to get it repaired and all dealers are too busy to address my problem until end of April. I have changed the thermostat on my car's many times, but I don't know where to look for it on the marine engines. Any ideas that might help me?! Thx
 
Sponsored Links
  #2  
Old 04-01-05, 12:12 PM
Ed Imeduc's Avatar
Member
Join Date: Aug 2002
Location: Mountain Williams Missouri
Posts: 18,389
Wink

Try http://www.defender.com they have the manuals and some parts for it.

ED
 
  #3  
Old 04-02-05, 04:59 AM
FredP
Visiting Guest
Posts: n/a
Thermostat

Thx for the reply, thats just what I did, replaced thermostat(s), but still overheating. Because of weak telltale I now am in the process of rebuilding the waterpump.
Once I had the lower unit off I attached a hose directly to the exposed watertube and ran the motor (less (lower unit). Water was squirting strong out of the telltale and exhaust, but the motor was still overheating. I am stunned and lost I thought for sure this would work. There is no waterflow diagram in the manuals, so I am assuming the thermostats are in the return path?? I checked for blockage in the cylinders and water runs freely. So the symptom is as if the thermostats still don't open, which I doubt since ther are brand new and I was careful putting them in correctly.
I believe until I can run the motor this way without overheating ther is no reason to assume that putting the lower unit back in will fix the problem???
Help!! I am at the end of my rope!
 
  #4  
Old 04-02-05, 05:51 AM
Member
Join Date: Nov 2004
Posts: 74
Overheat warning

Replace the temperature sensor? Remove carefully - they can break off!
 
  #5  
Old 04-02-05, 06:31 AM
FredP
Visiting Guest
Posts: n/a
Thermostat

thx for reply, I checked sensors with an ohmmeter first; they are both closed at cold and both open at alarm. Both cylinder blocks feel hot; too hot tookeep your fingers on longer then 3 seconds.
 
  #6  
Old 04-02-05, 08:08 PM
Member
Join Date: Nov 2004
Posts: 74
Thermostat

The manual does not have any troubleshooting references to your problem except for probable water pump replacement.

It does refer however to the use of 'thermomelt sticks' to test the engine for operating temperature. Touch a 140degree stick to the lower thermostat housing or the top cylinder. If it does not melt 'the thermostat is stuck in the open positionand engine temperature is too low. Touch a 170degree stick to the same spot, the stick should not melt. If it does the thermostst is stuck in the closed position and the engine temperature too hot.' These sticks are apparently vailable from your 'local marine dealer'. This is a more conclusive test than you have tried.

The manual is very clear that you should never operate a 2-cycle engine out of water or without a prop. the engine MUST be under load. If not, they claim the engine can 'run away' and not be able to be stopped. (Destructive)

I do not think a seizure is involved - it would likely power out and quit. Like turning the key off on your auto (at highway speed).

 
  #7  
Old 04-03-05, 07:04 AM
FredP
Visiting Guest
Posts: n/a
Thermostat

Thx, I am in the process replacing the water pump and do more testing.
 
  #8  
Old 04-03-05, 11:29 AM
FredP
Visiting Guest
Posts: n/a
thermostat

after replacing thermostat and waterpump and putting things back together everything worked fine; my "trick" of running without lower unit was not working
thx for your help!! Fred
 
Reply


Thread Tools
Search this Thread
Display Modes
Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On



All times are GMT -7. The time now is 10:44 AM.