2004 Johnson 150 Overheating

[Florida Tim]

I have a 2004 Johnson 150 which is overheating. Model is j150cxsob. Recent water pump. Mechanic open thermostat housings on top of head and ran motor briefly, flowed well. He has already gutted the thermostats since we live in Florida and really do not have cold water to worry about. Wants to overheat when running on a plane, no particular rpm, I do not run that fast, maybe 4000 +/-. Problem is intermittent. Goes into safe mode and begins to run like I hit hard bottom. Can shut down, key off then on, and reset and will go a little more before doing again. Engine head is too hot to touch so I think that I really am overheating and not just a sensor problem. BTW, got the motor without a lower unit. Mechanic put one on from prior year(s). Has run fine but not sure what the proper water pump is.

Any suggestions?? Or do I need to pull the heads? Does this engine have deflectors inside? Thanks for any help.

 

[cr2k]

Re: 2004 Johnson 150 Overheating

Thermostats do so much more then control the water temp. They also regulate flow and some back pressure is needed to force flow through some areas.

 

[Florida Tim]

Re: 2004 Johnson 150 Overheating

Thanks cr2k for the reply. Can anyone tell me if the water flow through the engine comes out of the thermostate housing and down through the head or the reverse? Thermostats are located at the top of the heads. Does seem like I have some sort of water flow issue through the engine.

 

[boobie]

Re: 2004 Johnson 150 Overheating

If that mechanic gutted the thermos, I'd question anything else he did. Find a new one. The thermos have to be in there to keep the mtr temp up at idle which is about 140*. I haven't seen any water here in FL that hot yet.

 

[Florida Tim]

Re: 2004 Johnson 150 Overheating

In all fairness to my mechanic he did save an island camping trip for the boy scouts by gutting the thermostats. And he has been able to get my carbs to stop leaking when they have warped. I can understand the need for back pressure at lower rpm. But I just cannot understand why at planing speeds I continue to have this problam.