how did you clean the heat exchanger? I've heard anything up to and
including muriatic acid. How old is you exchanger? A new exchanger for
about $150 may be an investment, at least so you can keep your old one
as a spare, but first try to see if you can get good water flow through
it.

Email me directly about the bypass,p lease, and I'll try to send you
pics.

cheers
mickey

I took the heat exchanger off with the intent of sending it to the radiator
shop but it was very clean and all tubes were clear so I gave it a quick
bath in some phosphoric (?) acid I had on hand. It came out very shiny. I
capped the ends and pumped in some air pressure let it sit over night for
each side to check for leaks. I would like to have a spare if you know of a
good used one.
-Allen