Heat exchanger question
I just replaced raw water impellers, and one of the impellers was badly damaged.* So I pulled the raw water bonnet off the heat exchanger to pick out the parts of the impeller.* I put everything back together and ran the engine (after replacing belts, filters and impeller) to bring it up to temp and an all around check.* I noticed a slight weep at the base of the heat exchanger bonnet, and assumed I needed to replace the gasket, since I had opened it up.* When I took the bonnet off, I had engine coolant coming out into the raw water side.
I pulled the heat exchanger and took it to a condenser shop.* They disassembled the tube bundle from the exchanger and pressure tested the tube bundle, which passed the test.* The technician noted that the O rings for the tube bundles look flat, so the plan now is to reassemble and pressure test the entire unit.
While the heat exchanger is in the shop, I did a "leak down" test on the other engine - filled the expanson tank to brim full, ran the engine up to about 2/3 throttle fro about half an hour to get up to temp, and then shut down.* At the end, lots of pressure in the expansion tank, no loss of fluid.* So, based on this rudimentary test, it looks like the second system is good.
One added note; this has been a fresh water boat for its service life; I purchased it on Lake Michigan, and have been cruising the Columbia River myself.
So the question is what to do.* Am I approaching end of life (its a 1994 boat), or just seeing bad seals, perhaps from the 6 month winter dry layups.
A replacement unit is $2 boat units, and significantly about a week away, which is getting close to my planned departure for the offshore run to Canada.
Any thoughts, advice?