johnson 150 xp thermostat replacement

coffeelover484

Recruit
Joined
Jun 14, 2011
Messages
4
I bought a 1989 johnson 150 xp tracker that when running is very warm to the touch but the spit tube is pushing good water pressure. l can't dind the model number plate on the engine to see what thermostats I need. can anyone help me. And should replacing the thermostats be the problem or is there a normal issue. the guy I bought the engine from said these engines do run hot at idle but cool down when running at higher rpms. FACT OR FICTION?
 

Will Bark

Lieutenant
Joined
Aug 1, 2010
Messages
1,470
Re: johnson 150 xp thermostat replacement

Yes, when the boat is running thru the water above idle there is more water going thru faster and it will run cooler than in a barrel or on the hose.
 

coffeelover484

Recruit
Joined
Jun 14, 2011
Messages
4
Re: johnson 150 xp thermostat replacement

yes but should the engine be too hot to touch at idle or is there a problem
 

Will Bark

Lieutenant
Joined
Aug 1, 2010
Messages
1,470
Re: johnson 150 xp thermostat replacement

Should be able to put your finger on it for a count of three or more. You can get an infrared thermometer at Lowe's for $30 which will tell you the temps. Mine at idle is about 150-160 degrees.
 

emdsapmgr

Supreme Mariner
Joined
Dec 9, 2005
Messages
11,551
Re: johnson 150 xp thermostat replacement

That engine will sound an overheat horn at 212 degrees. The horn will silence when the powerhead gets back down to 175. Normal idle should be around 140-150. You may see 155 at idle in late summer in warm lakewater. The telltale is a sign that the impeller is pumping water. It does not mean that the water is circulating through the powerhead. If one of the stats fails shut, the incoming water cannot circulate and you will get an overheat on that side. Rent or borrow a laser temp gun. Once on plane, the thermostat pressure relief valves open, flooding the powerhead with cool water-the powerhead temps will go down dramatically.
 

kenmyfam

Supreme Mariner
Joined
Aug 10, 2006
Messages
14,385
Re: johnson 150 xp thermostat replacement

Salt water motor by any chance ???
 

coffeelover484

Recruit
Joined
Jun 14, 2011
Messages
4
Re: johnson 150 xp thermostat replacement

thanks will check it out still waiting for an adapter harness t hook it up to the boat to test at home but it ran and started no problem when I bought it and I will get a laser temp gauge thanks to all
 
Top