Well I tried my hand at silver soldering the easiest one I could get to with really no luck... Not sure if I didn't get it clean enough or whats going on but I couldn't for the life of me get the solder to wet out to the tube.. It should have been clean enough. Most likely wasn't able to get enough heat into it..
I wasn't holding my breath that I was going to be able to fix it, so I'll wait on some responses from a couple local industrial radiator repair shops and see what they say, but at this point, I'm leaning towards replacement with a Seakamp or Mr. Cool unit.
On that note.. I'm seeing that there are both 3.5" and 4" heat exhangers for the 496 but the mercruiser parts diagram shows the same 4" model on all the serial numbers I've checked so I'm not sure whats going on there... Mine matches the dimensions of the 3.5" unit, so I'm wondering if they were supersceded or something and all are now replaced with the 4"... Anyone have any insight on this, or if I can use the 4"??? It seems like it would fit.
EDIT: Nevermind... did a little more digging and confirmed that the 3.5" unit is no longer available and is superceded by the 4" heat exchanger... which for whatever reason is 100 dollars cheaper at mr cool lol... I'll call that a minor win
