E32-3 M25 Alternator Bracket Retrofit

My M25 alternator bracket retrofit adventure has finally concluded. I discovered that boat repair is more free form compared to car repair. Sure there's a service manual for the M25 engine, but it only covers up to the exhaust manifold. Sure parts are available on the 40 year old engine, but scattered across multiple vendors, some with cryptic ordering process. Then, there are the mysterious and undocumented previous maintenance/repairs. Working 40 miles away from where most of my tools are was also a learning experience on planning and being organized.

The two harder than usual areas were taking the exhaust manifold off and finding the right parts. In theory once the nuts are off, the entire exhaust manifold/elbow assembly should slide off the studs. However, my exhaust manifold was stuck. Looking back, the heat exchanger was upgraded from the stock 2" diameter to the current 3". A larger diameter heat exchanger strapped to the smaller diameter mount, means the top of heat exchanger interferes slightly with the exhaust manifold/elbow assembly causing the exhaust manifold to bind against the manifold studs. I thought the rusted studs were causing the binding and was afraid to break them by applying too much force. Now, I don't know if that's even possible. Anyway, it took many weekends to remove the exhaust manifold.

Finding the replacement exhaust elbow was another challenge. I couldn't find it on Cataline Direct and couldn't find it elsewhere. Searching the forum turned up many different DIY solutions. Month went by before I finally found the exhaust elbow on westerbeke's website.

While changing the various hoses, I found a few hose clamps with heavily corroded screws. With a magnet, I found that all but one of the hose clamps were magnetic. As a result, when replacing hoses I discarded even the okay looking hose clamps and used 316SS(body & screw) hose clamps from McMaster.

The o-ring that came with the heat exchanger gasket kit didn't seal very well between the Hex screw and the end cap. I ended up using sealing hex head screws from McMaster for securing the end caps.

While finishing up, I broke the corroded siphon brake hose barb on the exhaust thru-hole elbow, and discovered a couple more heavily corroded hose clamps. That lead to replacing the exhaust hose from the water lifter/muffler to the thru-hole and I stacked bronze fittings to replace the original elbow.

On a side note, I used perplexity.ai to help me understand and recommend various repair methods. Graphite paste was recommended as a good thread sealant for the exhaust manifold/elbow assembly. Fast forward a few month and I've switched to using claude.ai for recommendations on thread sealants for the the exhaust thru-hole fittings. Out of curiosity, I asked about the graphite paste again and learned that graphite paste is not a good thread sealant for marine environment due to potential for galvanic corrosion because graphite is more noble than the surrounding metal. Oh', okay.

Time wise, if I know what I am doing, with all parts and tools, probably 2~3 days, but I don't know what I am doing.

Parts Costs:
Alternator Bracket Retrofit kit (CatalinaDirect), $603.80
Exhaust Riser/Elbow (Westerebeke), $412.50
Exhaust Flange (Westerbeke), $134.50
Various hoses, hose clamps, and fittings $500 ~ $600
Tax and shipping is another ~$10% and let's not count the extra tools, wrong tools, extra parts, and wrong parts.