Thermostat-how do I know it's working

[Snoopy-2]

I'm running a 98 Johnson 115 hp and was wondering how can I tell if my thermostat is operating properly. The motor does not appear to be running hot and visual water eject hole is working fine. I am not sure the engine is running at the proper temperature for efficiency.

 

[coolbri70]

Re: Thermostat-how do I know it's working

at the beginning the stats are closed, at the end the right side is open

 

[coolbri70]

Re: Thermostat-how do I know it's working

both t stats open

 

[bob johnson]

Re: Thermostat-how do I know it's working

can you hold your hand on a head for 3 seconds?

if so then it isnt overheating ....a cheap infared thermometer is such a fantastic tool......get one.

bob

 

[Bosunsmate]

Re: Thermostat-how do I know it's working

Check to see that it heats up quickly enough, if it doesnt it may mean that your thermostat/s are stuck open or not seating properly so it wont quite get to proper operating temperature for a lot of running conditions.

Put your hand on the heads and check that they heat up roughly the same. Often the starboard bank gets a bit hotter faster, ive never worked out why but they shouldnt be massively different.
Dont rev your engine just let the idle do the warming up, you should notice appreciable heat within 30seconds and be quite hot within at a minute. If that doesnt show up any problems you will probably need to test it after running at wot etc with the infra red gun Bob brought up

 

[Bosunsmate]

Re: Thermostat-how do I know it's working

Also they shouldnt get so hot you cant keep your hands on them for ten seconds or so.

 

[Chris1956]

Re: Thermostat-how do I know it's working

Pull the 'stats out and test them. It should be real easy to do. That '79 motor is significantly different than your motor.

 

[Chris1956]

Re: Thermostat-how do I know it's working

I am not sure where you could get an accurate flow of cooling water to test it's temp. The gratings above the antiventilation plate is probably your best bet, but the water could have cooled down by the time it gets there. So, I would test the 'stats and watch the water pressure gauge.