Reply To: 1961 Johnson 40 (RDSL-23) stops pumping water

[jdunham]

I was also concerned about an intake clog so I ran it without that plate/screen installed and there was no change.

Need2fish, I am not sure what you mean by outputs? I did my pump flow check with the thermostat out and cover off and water spews out at first and then just stops. Not knowing the water path well, it looks to me like that should be a direct shot from the pump, into the jacket around the cylinders, and then out the hole in the head. With the cover on it should either be directed down to the return side of the pump or out the exhaust.
I also checked at the output near the top of the block that normally feeds the automatic choke, same thing. water at first and then just exhaust puffs.

I have never removed the powerhead, but i suspect that it is a replacement. The block itself just has that flat red primer on it, no top coat present anywhere. All of the other parts are (were) white. If it is not the original powerhead it was replaced more than 30 years ago prior to my father acquiring the motor. I asked him about overheating issues today and he said that he never had any trouble that he could recall.
Would this blockage you mention be something that should be either present or not? As in an installation error or is it something that might develop over time.

The lack of water spitting was just what prompted me to look into it more deeply when I thought it was running hot. The lack of water flow at the thermostat housing and auto choke supply is what really has me concerned. The motor does have the over temp sensor on it which I think is just a switch that will close when it gets hot enough. I dont know what temp that will happen at and I dont trust it yet.

I will track down a thermometer, I know I have one somewhere. My primary concern there is that if the jacket is empty there is going to be less heat transferred to the outer surfaces which could give some false numbers. How hot do I dare let things get? I see the thermostat is 140ish F.

Am I wrong in my thought that without the thermostat installed and with the cover removed, the pump should just spew water out the top? Or that with them both installed, there should be a constant stream from the auto choke supply barb?