1997 Thermostat question

[jlw1972]

97 Johnson 115 Xflow Bubble Back

I bought a boat with this motor on it. The motor had broke rings on 3 cylinders. I rebuilt it .020 over and replaced everything except rods and crank as they were undamaged and the crank checked out fine. I rebuilt the carbs and fuel pump also. Just wanted to rebuild everything to say it was all done right. Put a new t-stat kit in also, noticing that it DID NOT have one in it when I bought it. Water passages in block were blasted out with a pressure/steam washer, water passages in heads were also cleaned to like new condition. Today when I cranked it for the first time, after running for a minute or two it got hot. Alarm went off and I shut it off. I decided to take the T-stat out. After removing it, everything was fine as for as temp is concerned.

Here's my question. I know that a T-stat was put in this motor for a reason when it was designed. Why will it not work?? I live in lower Alabama, Is it a regional climate issue? Something that is only needed in colder climates?? The situation just doesn't make sense to me. What's the deal??

Also,.. who ever designed these motors and decided to put the T-stat down there where it is, Needs a boot broke off in their ***!!

They should have come up with something different. If you know what I mean.

 

[boobie]

Re: 1997 Thermostat question

When you cleaned the block , were all the water deflectors in place and in good shape ??

 

[jlw1972]

Re: 1997 Thermostat question

Yes sir. 2 on each side. 4 total. I never moved them from their original location.

 

[Faztbullet]

Re: 1997 Thermostat question

Did you install them correctly a you can reverse-stat??

 

[Boatdoc58]

Re: 1997 Thermostat question

It is an obvious question, but did you replace the water pump kit and when you were running it was it on the "ears" or in a tank submerged above the water pump ? It sounds as if you did the job correctly and have many $ into it. Also check the plugs to see if it is running lean.
As you know the water pumps in outboards are "pushing" pumps as they are usually submerged completely when operating.With the ears there is always a little bit of air that mixes with the incoming water and can cause hot spots due to lack of water flow. If you must use ears tape them tight against the pick up. We ALWAYS tank motors after a water pump job to make sure they are operating properly.

 

[jlw1972]

Re: 1997 Thermostat question

No, I havent replaced the water pump yet but the one in it isn't that old. Doesn't have many hrs on it.

Tstas were installed correctly.

 

[anzomcik]

Re: 1997 Thermostat question

Did you run it on a hose with muffs? If so you need to have the hose running WFO, I was use to not having to have the the water cranked with my smaller motors I would run on muffs, and did the same with my 115, only to find out I needed the hose to be full blast to get water through the whole motor block. I was getting over heat alarm until I opened the hose all the way

 

[Bosunsmate]

Re: 1997 Thermostat question

Theres a little hole in the thermostat valve body, if that blocks the thermostats will never open.
Check to see if one head is running hot and the other not.
You can also drop the gearbox and attach a hose to the inlet tube if doing that keeps the motor in correct operating temp then your water pump is fading out