Johnson 150 overheating woes

[sidmcneil]

I have a 1992 Johnson 150 that overheats at idle (quickly). The heads get to 200 degrees pretty quick on the muffs. I put in a new water pump kit-didn't work, new thermostats on both sides-didn't work. Not sure what to do now. Anyone got any suggestions?

 

[sidmcneil]

Re: Johnson 150 overheating woes

Ok, for an update and more indepth explanation: the first time the warning buzzer went off, I took it to the shop for a new impeller. They replaced that, but when they tanked tested it, they said it got hot really quick and that they thought I needed new thermostats. The ordered new thermostats, put them in, and still no help. I brought it home for the weekend and he said he would look at it more on Monday. I just hooked it up to the muffs and ran it, and when I did, it didn't pee at all for about 30 seconds, then trickled after that. I felt the water coming out of the pee hole and it ws cold at first, then got hot (within 30 seconds). I also noticed that most of the water was coming out above the skeg. I turned the motor off, felt of the heads and they were too hot to touch for more than 2 seconds. There was also some smoke coming out by the pee hole. I am not a mechanic, just need some advice on what could be causing this problem. Help please!!!

 

[Chris1956]

Re: Johnson 150 overheating woes

It sounds like you have an obstruction in the cooling system, that is if the shop replaced the waterpump impeller and the thermostats correctly. Does your motor have the plug just under where the powerhead meets the midsection (in the back)? If so, that is the flush port. You might remove the plug and put a garden hose in its place. If you use gentle water pressure, you can see if water circulates. It also may blow out any debris. Pull the thermostats and see if water comes out there, the the intake grates on the lu, the grates above the antiventilation grates, etc.

When I kept my mercruiser in the water. the barnacles used to go into the intake passage below the waterpump, and clog things up. I had to remove the intake grates and use a screwdriver to clear them out. You might check this area on your motor.

If that doesn't work, you should pull the heads and look for debris.

 

[clint]

Johnson 150 overheating woes

I agree with previous post. You have to have an obstruction of some kind? After new water pump and thermostats you should of been good to go. I do also suggest to remove heads and check for blockage. Good Luck!
Clint

 

[gregr1971]

Re: Johnson 150 overheating woes

i had the same problem after a waterpump install, removed the lower unit, and the mechanic did not line up the water tube correctly, when he installed the lower unit ,he bent the tube up from forceing the gearcase on. you may look at that. also ,check to see if the gromment to seal the water tube in the waterpump housing is there.