New Yamaha 315 hp diesel with hydra drive

[hamadi]

You are absolutely right and the warranty conditions should be clearly specified. "general rules" are used by experts investigating abnormal engine failure.
I didn't mean to be alarming. Engines on the market have low rate of failure otherwise they wouldn't sell.
The point is we hardly find clear information for duty classification except for AIFO and ZF gear systems. I believe opacity is kept on purpose to reduce unfortunate boater claims.

[hard1]

It's an interesting subject. From personal observations I believe these Yamaha/Yanmar lumps are pretty tough considering they are not specifically designed for the marine market. And for them to survive as long as they do in a RIB for example, is nothing short of miraculous. For instance, the sump on a 240 Yamaha (and for that matter probably all the other models too) is made from untreated mild steel, same as for the road version. Mild bloody steel which is typically 3" above the bilge in most RIBs? It's a joke! I've seen at least 2 rot through following bilge pump failure (not an uncommon event) causing not only a minor localised ecological disaster but a £3k bill to repair a £10 part. I think owners should be more aware of similar potential fragilities if not pampered and closely monitored.

Having said that, they are cracking lumps.(!)

[hamadi]

These engines are marinised and several internal parts are different from the ones on road vehicles. Piston rings and other internal parts are made of different alloy to be more corrosion and wear resistant.

[Jelly]

The hard boat I mentioned was the Osprey 26' fisherman
www.ospreyboats.com
Rgds
Jelly

[hard1]

Originally Posted by hamadi

These engines are marinised and several internal parts are different from the ones on road vehicles. Piston rings and other internal parts are made of different alloy to be more corrosion and wear resistant.

Even so, a mild steel sump?

[hamadi]

Since we have only scarce information about the 4.2 l I got the following links related to engine trouble (315hp Yanmar)

http://www.freeboards.net/index.php?...&showtopic=261

http://www.freeboards.net/index.php?...&showtopic=327

http://www.freeboards.net/index.php?...&showtopic=105

[jackcastoff]

Hamadi, Interesting discussion. I have just bought a yamaha 420 to put in my pacific 22. It is rated at 240 hp. Subsequently on finding out the engine needed rebuilding, I tried to purchase the parts from a yamaha dealer but the bill for the pistons only was in excess on £2100.

I then sourced all the parts through a toyota and the majority of them were the same. The price of the pistons went down from approx £300 each to £80 each.

I too found out about the problem with the 1hd toyota block having lower end failures and toyota doing alot of warranty repairs. It seems amazing to me that yanmar have bought out a 315 hp version of the same block which i think was designed to do approx 160 hp in a car!

The most punchiest engine that i have come accross in the same range is the yanmar 4lha. 3.4 litres 240 hp. I would be very interested to find out what car that block was originally in. I have not heard about any failures with it either. I just wonder what sort of power we will get when these blocks are subjected to common rail diesel injection technolodgy.

[Richard B]

Originally Posted by jackcastoff

...designed to do approx 160 hp in a car...

little bit more as far as I know - a bit over 200bhp.

[jackcastoff]

Richard : Yes, i looked it up and you are correct. I presume that is the newer 24 valve model. I also presume that the higher hp yanmar block uses the 24 valve, as opposed to the 12 valve model the older yamaha 420 (like mine) has..... Interesting that the engine mounts have been a problem on the yanmars, my one has had the feet on the bellhousing welded up after what looks like they could have broken off. Although they look like pretty light duty cast aluminium.

[Richard B]

Originally Posted by Jelly

The hard boat I mentioned was the Osprey 26' fisherman
www.ospreyboats.com
Rgds
Jelly

On Saturday I met a guy who was delivering that boat to Eastbourne. He had some very complimentary things to say about the engine and reckons that there's no turbo lag at all.