Steve:
My boat came with those TAMD40s, 145hp, with 3000 hrs. In the next 6 yrs I put on another 1500 hrs. In that time I had to fix 1 starter (cheap) and I had some problems with the rubber boot on the aft end of the Heat Exchangers and some of the high pressure fuel lines started getting pinhole leaks. By then the engines were 20 yrs old, so I didn't expect them to be perfect, or to be cost-free. Still, the amount of $ spent on these items was neglegible.
The only other diesels I had owned by then were in my sailboats, and weren't so old, so I had nothing to compare the reliability with in my own experience, but I am in a club with a number of highly mechanically inclined folks with whom I talk engines, so based on that, I had no issues with cost or reliability.
I have moved up to the 200hp TAMD41s that I put in in 2000. I was able to sell the 40s for almost the same as I paid for the 41s, so at least the buyer shared my confidence in those engines.
The main difference between the 40s and 41s, from my experience, is in fuel efficiency. I got an immediate improvement of about 10%, and greater hp, so I was able to run at a slower rpm, saving another 5+%. The HE design on the 40s requires attention to the fittting of the rubber boot on the aft end. If you can keep that part from deflecting, you won't have the overheating that was the main irritation I encountered. If parts are expensive compared to other brands, I wouldn't know, as I haven't bought for other brands, nor did I buy any serious parts for the Volvos, due to their general reliability.
My present engines have cost me, in the last 12 years, other than what I put on the engines and knew about at the time of installation, oil filters, fuel filters, zincs (I should look at the air filters and impellers soon), oil, fuel, but $0.00 has been spent on parts.
I keep my boat in Vancouver BC, where cold weather starts happen, so I have also noticed an improvement in cold start smoking. Once running temp is achieved, neither engine is particularly smoky, especially when compared to other brands of the same vintage.
IMHO cold start smoking is related to the year of manufacture and not to the brand name of the engine.
Anecdotally, the worst, smokiest, made the whole dock disappear in thick smoke on every start engine was the pair of CAT 3208s in a Canoe Cove 41 built in 1973. Thankfully that one is gone from our club now, so we rarely see anyone with a serious smoking issue.
