Heat Exchanger cooling for Bukh

I have just had to re-build my Bukh Diesel for Voila following some rust particles temporarily jamming up the raw water cooling system at the exhaust elbow outlet. This led to a damaged head gasket which led to salt water in the head, valves, and cylinder.

Taking the engine apart, I was really shocked to see what salt water had done to the head and the cylinder block. I was able to salvage them both, but did not want to subject them again to salt raw water cooling, so I embarked upon working a second pump to drive the coolant around and install a heat exchanger. For the record, Bukh's workshop manual for this engine says that it cannot be done. Wrong!

Yesterday I put the boat in the water for sea trials with the new kit, and am happy to report that everything works perfectly. In summary, I turned a new pulley out of T6 aluminum of 4" diameter to fit on top of the flywheel, fixed by the nut that holds the flywheel. I made the pulley so that it sticks up a bit giving about a 15mm clearance between the belt and the top of the flywheel to allow room for a knot to pass through if one has to use the rope pull for emergency starting. A new Orberdorfer centrifugal pump was purchased on Ebay for $115 and mounted via aluminum brackets fashioned from 3/16"x 3" L aluminum stock and fixed to the port side of the engine using 8mm female threaded bosses already provided on the block. A new heat exchanger was custom built with integral expansion tank by San Juan Engineering and Manufacturing in Bellingham, Wa for $250. Dimensions are 9" long, by diameter of 3", with a total height of about 8" including radiator cap. This mounts on aluminum brackets fixed to the front of the engine using the existing steel mounting bracket of the engine. It is fixed to the engine by four 8mm nuts and going onto about 30mm studs in the engine block. I double nutted those studs to remove them, and replaced them with 50mm studs so that they could be used to hold two strips of 1/4" x 2" aluminum to which I fixed the heat exchanger/expansion tank combo. This was necessary in order to get the expansion tank to be at the highest elevation of the cooling system. A belt of A section x 27" drives the second pump off the top of the flywheel. The rest was simple plumbing done with standard 1/2" heater hose from our friendly auto parts supplier at Triton.

With nothing to copy, I went through some trials and made some errors along the way, so my process of evolving this was not as simple as it will be for the next person. If anyone is running in ocean waters and has concerns regarding the longevity of their little Bukh, this set up is a good idea. Anyone interested can contact me for more details and photos. Even with Bill's help, I have not been able to post pics, however I will work on this. I have not taken pics of the set-up installed, but will do this tomorrow. It is most comforting to know that my engine is now not breing eaten away by the minute.