I got back to the boat and picked up the manuel. It looks like if I disconnect the raw water lines on either side of the heat exchanger that should eliminate all but the exhaust elbow as a problem. I will also take the advise to change out the zinc and clean the exchanger while I am at it. Thanks again to everyone. This old farm boy is used to working on tractors and trucks but still learning all the little ins and outs of the boat engine.
Cabo Rico 38