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Wotname 16-11-2019 21:42

Re: Yanmar 3YM20 vs Beta 20

Originally Posted by Dockhead (Post 3017241)
It's simple -- indirect injection uses a pre-chamber, and direct injection does not.


The thing I like best about direct injected diesels is they are much easier to start. My 4JH3 HTE starts if you just look crossways at the starting key -- does not require even a full revolution even in subzero weather. I have never used the air heater and I'm not sure it even works.

Previous indirect injected diesels I've owned have been more challenging to start, and required the use of glow plugs.


Thanks for the explanation.

I don't think the claim that indirect injection makes the engine hard to start is universally true. I don't dispute that it may be true in some instances or for some engines..

E.G. Both of the 2GM20 engines I had started in the same manner as your 4JH3 HTE. Look sideways at the key and think start! They have pre com chambers and no glow plugs.

Perhaps it makes a difference if engine has lost some compression and/or has a compromised electrical supply to the starter motor. I can't speak to those conditions 'cause I haven't experienced them on an IDI engine!

ramblinrod 20-11-2019 10:16

Re: Yanmar 3YM20 vs Beta 20

Originally Posted by ramblinrod (Post 3013099)
Clean air and fuel is important to every ICE on the planet. I donít believe there is any difference in sensitivity between common rail and cam driven pumps, an injector orifice is an injector orifice. How the injector is driven has no connection to the fuel supply IMHO.

Thanks to those who questioned.

I have been very busy winterizing boats as a result of recent cold snap, and have not been able to post.

I stand corrected on two counts, a result of posting from memory, while rushed to perform boat winterizing services, without any fact checking on my part.

First, the Yanmar 3YM series does not incorporate common rail fuel injection technology, as I previously stated.

There has been a lot of discussion surrounding this technology, and I erroneously associated it with the Yanmar 3YM line. I knew better, it was simply "a momentary lapse".

Under this false presumption, as my experience with the 3YM line is that they are very, very reliable, I responded that the common rail technology is no more susceptible to fuel contamination than mechanical fuel injection.

This should have simply read, the 3YM is not prone to fuel injection problems or any more sensitive to fuel contamination than any other small rec boat diesel.

That said, it is true that common rail technology engines (which the 3YM is not) may be more sensitive to fuel contamination than mechanical fuel injection engines, from the perspective that the fuel pressure is much higher, and orifices may be smaller.

But the truth is, as I stated, that all diesel engines require clean fuel and air to perform reliably; meaning that regardless of fuel injection technology it is or utmost importance to feed clean air and fuel to every diesel engine. A slug of dirt or water can stop a diesel of any technology, dead in it's wake, and I have performed many repairs on poorly maintained, non common rail engines, to prove it.

The advantages of common rail technology are numerous, and like every design or purchase decision, there are pros and cons.

To me, for the larger Yanmar rec boat engines, the benefits of improved performance, fuel economy, ability to modify the fuel injection parameters if needed, and carbon emissions reduction, warrants consideration despite the possible higher sensitivity to fuel contamination (which should not be present in the first place). This could prove very important to the average boater as environmental regulations become more stringent, as we all know they will.

The same holds true for turbos. Yes they add moving parts which, and as such are an additional potential failure point, but improved performance, better fuel economy, and emission reduction is the benefit.

Notwithstanding, the 3YM series does not incorporate common rail technology, so this is simply not a consideration when evaluating a repower opportunity with one.

Based on my experience with these engines, from the vessel to the corporate level, given a choice between a Beta and Yanmar repower, even with the Yanmar was 20% more expensive (which they usually are not) I would choose the Yanmar every time BEFORE I became a Yanmar dealer, solely based on my experience servicing ALL diesel engines used in marine applications for rec boats from 20 to 50 ft.

Sorry for any confusion my previous post may have caused.

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