Yanmar engines

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Sailfree

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I understand that most boat engines are marinised diesel engines made by other manufacturer - many being Kuboto plant engines based.

I therefore assume pistons etc can be bought more cheaply from say the Koboto source.

Any truth in this and does anyone know what a Yanmar 4JH3-TE , 75HP is based on?

When I asked this before I was told that Yanmar design their own (except larger engines based on Toyota)

Surely though if i want say a piston Yanmar did not decide on a unique size but took one from another engine?
 
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Yanmar make diggers and generators and industrial engines.
I'd guess many parts are common.
You can get Chinese copies of some Yanmar small engines, and pattern parts for engines.
 
The difficulty will be the simple practical matter of obtaining the exact physical specs of the Yanmar standard part and trawling other sites for the same info on their pistons, and matcing them.

You may strike lucky and find someone selling pattern parts but even for the common Ynnies this is far from easy or comprehensive.

You might try posting on some of the US boating forums as they have a vastly bigger support network and knowledge than we do in UK.
 
Next door neighbour is a John Deere groundcare dealer - a lot of the larger JD machines he brings home to play with are Yanmar powered. Mind you I doubt that JD parts are exactly bargain basement.
 
Sailfree said:
I understand that most boat engines are marinised diesel engines made by other manufacturer - many being Kuboto plant engines based.

I therefore assume pistons etc can be bought more cheaply from say the Koboto source.

Any truth in this and does anyone know what a Yanmar 4JH3-TE , 75HP is based on?

When I asked this before I was told that Yanmar design their own (except larger engines based on Toyota)

Surely though if i want say a piston Yanmar did not decide on a unique size but took one from another engine?
Click to expand...
My local engineering shop with a Churchill crank grinder used to have a Hepolite catologue, every engine that you can think of was in there with all the dimensions of the pistons
 
I had a broom with some yanmar’s 6 cylinder 435’s they were the same Toyota Land Cruiser
 
Sailfree said:
I understand that most boat engines are marinised diesel engines made by other manufacturer - many being Kuboto plant engines based.
Click to expand...

Not true albeit a common misnomer.

Engine makers are designers, integraters and assemblers. They rely upon a network of suppliers for many of the components such as pistons, bearings, springs, valves, clutches, fuel injection equipment, turbo etc. A marine engine will likely have a different power delivery curve compared to a road or other stationary engine application. It will also have different duty cycle, rating and durability specs.

The engine maker will work with its suppliers to optimise component specs for the application. Mahle, for example, is one of the largest suppliers of pistons. I can’t imagine that there is much commonality of part across their customer base, albeit many may start from the same casting or forging.

The part number should be the individual identifier. Getting hold of it and being able to cross reference it to the makers p/n and any like-for-like alternative is a challenge.

Some engine makers buy complete engines from other manufactures. This is usually where a gap in their own product range exists but not big enough of a market to develop their own product. The little Volvo engine made by Cat/Perkins is an example. Volvo will present a product spec to the supplier and will have a big influence in ensuring that the engine meets their requirements and hence carries their name.
 
Servicing a RIB with a 150hp Yanmar outdrive unit. Local Yanmar guy had not seen one, so Iooked carefully around it and found it was a Toyota engine, easy to find parts.
I understand that parts for the small older engines are available in OZ, were they are common in small ag machinery.
 
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