The problem is when you are dealing with engine manufacturers (ie Volvo). You can't cross reference the engine to anything else. It's a Vulva and that's it. But if the model is old enough, it is possible that a generic diesel repair shop/parts supplier will be able to reference jobber parts for it at much lower cost. Someone will have to take a trip into the boonies and ask about their engine, and then post here.
BTW, who's in charge here? Who has the god-like authority to start a sticky?
Volvo is Swedish for "You're Screwed." Seriously, some Volvo stuff is good, some is junk, it's all expensive. I have an MD6A in my sailboat. It's not a bad engine, it's the parts that kill you. $165 for a valve?#$$@$$@ c'mon. $107 for a set of rings? Are you kidding me?
The best thing going right now is Kubota. Followed closely by Isuzu. The reality of it is that marinizing isn't that complicated. It basically boils down to water cooled exhaust, heat exchanger, and raw water pump for a diesel. Past that it's all about space constraints and service points.
I've learned alot by looking at bigger boats. The big cruising boats (power) don't mince words about using big truck engines. There are a number of places that make manifolds for them. Seems to really take some digging though.
If you are determined (and hey we are Sailors aren't we?) you can get a Kubota engine. Japan has very strict emissions requirements. So the engines get yanked after 3 years and sent here. A few companies specialize in this and the engines aren't very expensive. Parts are DIRT Cheap. Beta Marine and Universal/Westerbeke use Kubota pretty extensively. So if you buy the block you can get the other few parts from them. Rumor is that Beta won't sell them to you... or you'll pay $1000 for the exhaust manifold.
I honestly don't know why you have to have a water cooled exhaust manifold. That just seems to be begging for trouble. I don't understand why you can't run a hot exhaust with a injection elbow 5" away.
the stock Kubota Z500 (Westerbeke 5411/M15) exhaust manifold is $80. That's a brand new price!
Moyer marine is another source that deserves kudos. He specializes in Atomic Bombs... but he will readily admit that the same things apply. His prices are very reasonable for the things you can't make yourself. Although why on earth would you pay $45 for some galvanized pipe and nipples? umm here sailor sailor sucker.
Anyway, Moyer has solved alot of these issues for the Atomic 4 so you can apply them to other small marine blocks.
I really don't see why someone isn't selling a conversion kit with instructions.
My experience so far is that most "marine experts" border on scam artists. There are some gems out there, but probably 60% of the "experts" are shifty and overpriced. I had two "experts" condemn my MD6a as "dead"... that was 2 years ago. It is certainly cranky, but not dead.
As for tractor repair.... most small construction equipment uses the same power plants. little 20 to 50 hp kubota etc diesels. If you are willing to tear down the engine and bring the head and block to a shop, there are machine shops that specialize in this and will do the "hard" specialized work for reasonable prices. By hard work I mean the milling and valve grinding.
The trick to identifying your Kubota block is to look for it's serial number. Kubota has a nice page on this. The japanese page is much better (link surprssed by forum)
The dipstick has the model number engraved on it for some reason on Kubotas. This is the simplest place to find your model. The first character of the serial number denotes the year of manufacture. The second is the month. My block is Z500-2Bxxx Meaning Z500 engine, 2002, Feb. xxx serial.
Another great resource : (link surpressed by forum)
Grey market tractor is a whole other post. But this is a list of engine models and oil/air filters. As a bonus it has the tractor model numbers. When you go to the dealer life is alot simpler if you tell them you have a tractor. Although you may choose to tell them you removed the engine for another purpose such as pumping water... (under your hull). lol.
Fuel and Air filters may be changed by the marinizer, so double check them.
I had hell finding the Fram Oil filter. (rymes with Morrison) does a great job of hiding that along with westerbeke. Cost at Autozone $6, Cost at discount retailer $9+shipping.
I actually prefer to use a automotive alternator.... Autozone has a lifetime warranty. lol.
One other tidbit. Use an impact wrench to get your pulley nut loose. It will make very short work of it. Just watch your fingers and don't touch the contacts on the back. Some alternators bite when provoked.