overheating 40 Johnson

My 40 Johnson run in salt water(not sure what year, model # J40ELCUD) was running fine until it sat idle for 5 months. Now it overheats and little or no water is coming from the tell-tale. I replaced the water pump and it still doesn't work. As it heats up in the first minute of running the tell-tale goes from shooting some water to spitting and then to steam. I took the lower unit off and put a wire up the water pipe, still nothing. The telltale hose has no blockage either. I can run water thru the system with a hose just fine until the engine heats up and then, in less than a minute, it stops spitting water. Somebody suggested to me that the thermostat might be bad. Does that sound reasonable and how hard is it to replace? What are the other possibilities and solutions. Thanks a lot for the help. Splash2

Re: overheating 40 Johnson

Moving to Johnson Troubles.

Re: overheating 40 Johnson

splash2 - First a big welcome!!<br /><br />Replacing the thermostat would be the next step. You might also want to drop your lower unit after you have the thermostat cover off and backflush the motor from the water pickup tube.<br /><br />I have also seen older salt water engines that had a high enough buildup of the salt water crud as to be an obstruction in the water passage. I doubt that this is your problem as you do get good water flow on startup.<br /><br />If you have an OMC shop manual it will have a diagram of the water flow. - - You do have a manual - - ?

Re: overheating 40 Johnson

Splash,<br />I use my motor in salt water all the time, since I live in Hawaii. After changing your thermostat one product you should try is Salt-away I use it after every outing and motor stays clean inside. You flush the motor with it and it should clean it up quite a bit. It might take a couple of applications and the total cost is about $30 for the applicator and a quart of this stuff.