Reply To: 1959 Johnson RDSL21 35hp issues

[Tom Alexander]

Definitely gets your hand wet if you put it in the output stream of that upper discharge port, but at idle the temperature is not at all uncomfortable, just warm. I should have put a container in the stream to try to quantify the volume of water! But at about 14-1500 rpm it’s too hot to hold your hand there for any time at all. I don’t think the heat is in the water but actually in the combusted gases coming out there. I wonder why none of the engine pieces are showing this same increase in temp. I guess that water is REALLY doing its job!? OH, I forgot to mention that I have a copy of the Red Book. Down loaded it at the suggestion of one of you great guys a couple of years ago while I was rebuilding the lower end. Lost of info there! Thanks for the cooling flow diagram. I think the RDX-20 and 21 must be same enough to not matter. Well I will try to get this one out on the water, run it up and see what the temperatures look like at various points after a hard run.  Thanks all!  Tom Alex