Johnson 15hp '86 Thermostat - Two Thermo's listed?

[BaitThrower]

Hi all, another quick question. Got an '86 Johnson 15hp and the parts diagram lists two thermostats, one for early production 86 models and one for late production 86 models. I ordered a new thermostat in from the USA based on a parts list here in Oz which gave me the late model thermostat I believe. When I pulled the thermostat out of the motor (after I already ordered the new one) I discovered it is the early production (older) thermo. They are a different design but same flang diameter. Later model has slightly longer shaft though....

Does anyone know if they are interchangeable?

 

[tashasdaddy]

Re: Johnson 15hp '86 Thermostat - Two Thermo's listed?

i would say not. or they would not have changed it.

 

[BaitThrower]

Re: Johnson 15hp '86 Thermostat - Two Thermo's listed?

I asked a local delaer today and he said it probably would work ok because the newer stat supercedes the one that was in my motor...

Anyway I put the new one in and as far as I can tell, it should work as it is not obstructed by anything and is held in the same manner as the old one. In fact, the newer stat design looks like it will be much less prone to blockage and buildup,which is perhaps why they changed it?

 

[BaitThrower]

Re: Johnson 15hp '86 Thermostat - Two Thermo's listed?

As an update, I went ahead and installed the thermostat I had which apparently is compatible although a little different in the design. Started her up today and with my IR temperature gun recorded the temp on the head of the motor.

At continuous idle she gets up to around 160 degrees F but at fast idle the water flow picks up and cools her back down to around 145 degrees F which would be in line with the thermostat opening at 143 degrees.

So basically, it appears the newer thermostat is working fine, and I am a happy camper!