My son started sending me photos of potential yachts he is interested in. I am happy and we are talking about possibly East Coast 31s, Traditional 30s, Cavalier 28,30s, Northshore 27s, something simple that won't be trouble and will be okay to sell if he wants a bigger boat later. (Or he can steal our family cat after he remembers his mojo)
I can build and rig boats so none of the rigging and hull stuff worries me, but I haven't ever owned a diesel. For the 40 years of boat ownership I have only ever had multis with outboards. I love my 4 stroke Yammies - they are super reliable and compared to diesels, awfully cheap. You can bring them ashore and work on them and there are heaps of parts available. They don't have stuffing boxes and saildrive seals or alternators (well they do but I don't care if they work or not), they don't need super clean fuel or rust out their exhaust manifolds or somesuch. I get worried about having to buy a totally new motor if we get this wrong.
But I see boats with Buhk 10s and older Yanmars and I remember being around family boats that had problems with diesels starting, or overheating or just thumping away. On Seabreeze people say that Buhks are hard to get parts for. I can strip a motor down to a crankcase if I can remove it from the boat - but I will need seals and spare motors for parts would be nice.
So what should we be looking for, and keeping away from, when looking over 30-40 year old monos when it comes to diesels?
ThanksPhil

Yanmars are pretty easy to get parts for. Look for evidence of good instalation and servicing to start with. If its filthy and rusty expect servicing to be poor as well.
Generally if a diesel starts without excessive cranking its likely in decent condition as far as compression and fuel system.
Make sure you see it start from dead cold.

I just replaced a late 80s Sole 10hp 1 cyl (Sole marinised Lombardini diesel with Ronim gbx) with 2005 year built low hours Beta 13.5hp 2cyl (Beta UK marinised Kubota diesel TMC gbx) I got for $1200 18months ago. Big job but worth it. The Kubota based diesels are marinised by Beta (UK, Aust agents), Nanni (France, Aust agents) and WM Diesel at Mona Vale. I was very lucky to get the Beta - have to be fast with cash when they come up. Beta Taren Pt are also the Bukh agents but are selling way more Betas than Bukhs these days. Parts readily available. 2 cyl diesels far less vibration than single cylinder.

Realise off topic but Cav30s are excellent. I used to have a fractionally rigged one with sail drive. Best to get shaft drive if you can. Santana 30s also great but older.

So what should we be looking for, and keeping away from, when looking over 30-40 year old monos when it comes to diesels?
ThanksPhil

In general, what you see is what you get.
If it is a rusted heap that the owner says, "Oh, It usually starts right up. This is strange". It is a rusted heap.
Doesn't matter if it's a Yanmar, Volvo , Bukh or whatever.

If it is clean and tidy and starts up and runs. That's is what it is.
I reckon you will recognize a dog when you see one Phil.


The middle ground is probably what you will come across the most.
Looks Ok but does't start/run well.
Looks bad, but runs sweetly.
This is where the brand makes a difference and I would go Yanmar in this situation simply because it is Japanese.

gary

? You can find something with a outboard well in the cockpit/lazarette,but not a bracket off the stern !
Or handy enough to install one,without jeopardising structural integrity ?
Mason

There are two types of diesel in yachts. There are marine diesels and then there are converted industrial engines. The small marine diesels have the big flywheel on the front. I have owned both and I think as long as the engine has at least two cylinders, either will do. Two-cylinder Bukh or two-cylinder marine Volvos are just as quiet and smooth as the cement mixer motors if they use the same sort of water mufflers, engine mounts and shaft couplings.

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Kankama said..
On Seabreeze people say that Buhks are hard to get parts for.

My only experience with a diesel was a Bukh 10, single cylinder with a flywheel. I made the fatal error of trying to fix a leak, and things went downhill at a rate of knots. Parts are expensive. I found that I could source them from the UK or a shop in Auckland. The shop in Auckland had one of the last two exhaust elbows in the Southern hemisphere - the old one had cracked. Someone with more experience and knowledge might have done better. For more details, see my blog, e.g. theboattinkerer.blogspot.com/2022/08/episode-40-conceding-defeat.html

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Planter said..
? You can find something with a outboard well in the cockpit/lazarette,but not a bracket off the stern !
Or handy enough to install one,without jeopardising structural integrity ?
Mason

Yep my Clubman 8 is great in that regard. Boat looks like it has an inboard and controls are like an inboard. No obstruction in cockpit floor. Weight is way further forward than transom mount
Some don't like steering in reverse due to offset to one side but you just have to be aware of it's characteristics.

Phil - My amateur mechanic quick marine diesel checks If it takes a long time to start like 30 seconds+ cranking somethings not good. Check its compression with a gauge. Check the CSV fuel filter to see if the fuel is clean. After it starts check its cooling water is exiting the engine. You can also check its sea water intake filter if it has a clear top to check that cooling water is coming in. Listen to it and slowly increase and decrease revs and check for out of place clanks, whirring or vibrations. ie worn bearings, shot valves. Run it hard in gear against the mooring for a bit or out on the water. Check no black smoke from exhaust. A little is OK flat out. Do the same astern to check gear box. Feel the gear box temperature. They often have their own cooling system. Once the engine is hot try stopping and starting it again. A classic is that diesels start when cold but not when hot. You also want to check that the engines stop mechanism works. While its running check under the engine for drips of oil or water, a sign of seals or gaskets shot.
Then leave it idling in gear a long time and feel if the block is too hot. You can check with a temperature gauge. Then crank it up and leave it running at cruising revs and also check if its block is hot. Make sure the cooling water exiting the boat isn't mixed with steam or oil!

Good summary. For an excellent ~200 page intro to diesel basics at $30 see here; more than 350 illustrations, 8,000 copies sold. I have nothing to do with the book's seller or author, but have bought one.

www.whitworths.com.au/marine-diesel-basics

I once looked at a steel Van der Stat.
It had a ten minute dipstick. Ten mins to find it, ten mins to get it out and ten mins to replace. BTW the oil was as black as night.
I walked.....If it is too hard to check/service/replace the usual maintenance items, it probably hasn't been done.

Thanks everyone - some great tips