1975 Johnson 15hp running HOT. Am I missing something?

[Bombard Brent]

I recently purchased this very clean motor that had sat for >10 years. It started without much effort, but there was no water coming from the blubber hole and the head became very hot to the touch quickly. So...
-I replaced the water pump even though everything looked great.
-I pulled the water cover and found that there was a small amount of blockage around the thermostat. I cleaned and cleared the blockage and replaced the thermostat. The rest of the water jacket from what I could see was pristine.
-With the water cover off, I hooked the hose up to the water tube and turned the hose on. At first, nothing, and then a release of pressure and water (with some crystals) from near where the thermostat sits.

After I reassembled the motor, I ran it on muffs and in a tank. There were dropplets coming out of the blubber hole (almost scalding hot) and the head still felt very hot, although not as hot as it was prior to replacing the thermostat (I could hold a finger to parts for around 10 seconds).

Perplexed,

-I took the lower unit off again and examined the pump. It looked good. I hooked a hose up to the water tube, but I don't get any return (presumably because the thermostat is closed).
-I pulled the head to see if I could visualize any obvious blockage. It was pristine.
-Finally, I opened the water cover and removed the thermostat.
-I started the moter and the result was that there was a spray from the blubber hole and the head did not feel hot to the touch.
-Lastly, I put my new thermostat in a pot of hot water. It started opening around 150 degrees.

My confusion comes in part due to having a 1974 Evinrude 9.9 that has never let me down. It sprays a nice mist out of the blubber hole and the head is always cool to the touch. Am I being overly concerned by the seemingly hot operating temp of this motor? The water pump is good, the circulation appears good, the thermostat works, but jeeze it seems HOT! I am going to put the thermostat back in tomorrow and use a infrared temperature gun to see how hot it is getting unless someone can point out something obvious for me to consider.

Sorry for the long post, but I'm running out of ideas.

 

[Rick.]

Re: 1975 Johnson 15hp running HOT. Am I missing something?

I think your doing all the right things. Let us know the readings you get with the temp. gun. Your 9.9 should not always be cool to the touch. Are you sure it has a working stat.? Best of luck. Rick.

 

[Bombard Brent]

Re: 1975 Johnson 15hp running HOT. Am I missing something?

No, I'm not sure the 9.9 has a working thermostat. Based on the manual (125 degrees low end) I would say it doesn't. However, it has always run well and hasn't fouled a plug. I guess I'm more concerned about overheating than running cold. I will post the temp readings with the thermostat in when I get them. Thanks.

 

[raczekp1]

Re: 1975 Johnson 15hp running HOT. Am I missing something?

hi.
before water enters to powerhead from water pump is flating threw water pipe, and just before enters powerhead, there is a rubber gromet under powerhead.this gromet can lock(swalow) and restrict any water flow.
if this gromet is ok then water just enter to side plate cove/water jacket/refil this chanels and in upper part is a smal hole alowoing water to enters incylinder chamber to cool down cylinders and part of head.if temp reach right level, termostat is opening and water flows out from motor/powerhead

 

[Bombard Brent]

Re: 1975 Johnson 15hp running HOT. Am I missing something?

I replaced the thermostat today after getting my hands on a infrared temperature gun. For some inexplicable reason, there was a significant increase in the water from the exhaust outlet. I took temperature readings as it ran from several parts of the head. The highest reading I saw was 152 F at approximately 3000 rpm. The head was more cool to the touch than it was yesterday with new stat in. So, is there a break in period for t-stats? Don't get me wrong, I'm happy the motor is pumping water and within operating temps, but I can't figure out why yesterday it was too hot to touch, and today it seems to be circulating so much better. Anyhow, just thought I'd follow up with a conclusion. Thanks for the replies.

 

[Rick.]

Re: 1975 Johnson 15hp running HOT. Am I missing something?

My best guess is perhaps you had the water level higher up the lower unit on the second day? Rick.

 

[Bombard Brent]

Re: 1975 Johnson 15hp running HOT. Am I missing something?

I always fill the can to overflowing before I start up my motors. One detail I forgot to mention. While the lower unit was off, I spun the motor upside down and sprayed a liberal amount of Corrosion Block into the water tube. After a couple hours, I turned it right side up, put the lower unit on, pulled the thermostat and ran it in the barrel. Perhaps there was some corrosion somewhere that was blocking water circulation and the corrosion block helped break it up?

 

[Rick.]

Re: 1975 Johnson 15hp running HOT. Am I missing something?

I always fill the can to overflowing before I start up my motors. One detail I forgot to mention. While the lower unit was off, I spun the motor upside down and sprayed a liberal amount of Corrosion Block into the water tube. After a couple hours, I turned it right side up, put the lower unit on, pulled the thermostat and ran it in the barrel. Perhaps there was some corrosion somewhere that was blocking water circulation and the corrosion block helped break it up?

Could be that or it could be that you got the water tube aligned in the rubber grommet on top of the pump better the last time. Good to hear it's improved in any case. Rick.