Yanmar 3YM20 vs Beta 20

[donradcliffe]

As an unbiased customer, I would take the Beta hands down. In my experience, the Kubota engines are better built and more reliable. Parts are available from anyone at a reasonable price, compared to Yanmar's system of requiring you to buy from a dealer whose market (and markup) is protected.

While I was in Australia in the 90's, I heard of half a dozen catastrophic Yanmar failures in engines with less than 2000 hours, and Yanmar warranties offered NOTHING. I sail Tuesday nights on a Catalina 320 with a Yanmar 3GM. The owner has spent what a new engine would cost keeping that one running since 2000.

OTOH, I put a Beta 50 in my Beneteau as a repower, and my only problem in 2000 hours was the oil change pump, which Beta gave me a free replacement for. I talked to a friend who bought an Olson 40 with a 20 hp Kubota-based engine. The boat was on the beach after the famous Cabo storm, so he had it towed home and the engine torn down by his trucking company mechanics. They told him it was built like a Swiss watch, and had bearings not seen in other engines under 500 hp. I did the Baja Bash in a sistership. The Kubota overheated so badly it seized. We let it cool, but more water in it, and motored another 600 miles--no permanent damage. If it had been a Yanmar, at a minimum it would have need a new head gasket.

Not all Yanmars are bad--I've motored over 500 hours on several boats with the 4JHTE engines, and they are pretty reliable as long as you give them clean fuel with no air bubbles. They also have a good cooling system and are hard to overheat.

[Snowgoose35]

Originally Posted by Mike Banks

A 3 cylinder diesel engine usually runs more smoothly than a two cylinder--so if vibration is a consideration I might source a 3.

I have a 3YM30 and it purrs.

The 3YM20 is a 3 cylinder as is the Beta 20

[Q Xopa]

Originally Posted by ramblinrod

Regarding replacement parts, Yanmar has the widest dealer network for marine engines in the world....by far.

In the first 20 years or 5000 hours of ownership, if you maintain your Yanmar properly, all you should need is oil, filters, belts, impellers, and possibly a thermostat, all in stock and very inexpensive from your friendly neighbourhood Yanmar dealer, or favourite online discount Yanmar retailer.

I’ve heard lots of round the campfire stories, but I have yet to meet a Yanmar I didn’t like. If I had a choice of two boats to purchase, everything equal, but one with a Yanmar, the other a Beta, it wouldn’t take one second of thought to choose the Yanmar.

The installed base is huge. There are used engines and pard everywhere. I can often get rarely required replacement parts for a 40+ year old Yanmar, within 24 hours, maybe 72 if it has to come up from the US.

3 years ago, was about to pull the trigger on a 3YM30 for my personal boat, when I found a 1985ish Yanmar 3GMF, that I knew /respected the shop that serviced it its whole life. Snapped it up after the shop test, where the engine started for the first time in weeks, in what felt like a fraction of a second Before I actually depressed the start button. I have absolutely the same affinity for the 3YM30. They come standard on many major production boats in the 28 to 35 ft range. Great engines.

Re Stories of ECU lightning issues. Anyone here ever had to replace one? I didn’t think so. (The VP issue is a completely separate thing, grips design file followed by total incompetence). I feel for VP because employees with “P Eng.” after their name shoulda done better.

If any diesel 12 Vdc system gets hit by a direct strike, such as to hurt the ECU, there will be far more issue than just the ECU, like rings welded to the cylinder walls.

By the way, if a boat mechanic tells you that you need a new ECU due to a lightning strike, tell them you will need the old part to send to Yanmar for analysis. 90% chance there is no issue, 9% chance they will replace the bad one as a spare for you, if you ask nicely. (They are truly that great of a company.)

Being an agent is your opinion unbiased?

I am also a Yanmar owner, so I definitely am a biased happy Yanmar owner.

But I also know of many happy Beta owners.

[Q Xopa]

Originally Posted by donradcliffe

As an unbiased customer, I would take the Beta hands down. In my experience, the Kubota engines are better built and more reliable. Parts are available from anyone at a reasonable price, compared to Yanmar's system of requiring you to buy from a dealer whose market (and markup) is protected.

While I was in Australia in the 90's, I heard of half a dozen catastrophic Yanmar failures in engines with less than 2000 hours, and Yanmar warranties offered NOTHING. I sail Tuesday nights on a Catalina 320 with a Yanmar 3GM. The owner has spent what a new engine would cost keeping that one running since 2000.

OTOH, I put a Beta 50 in my Beneteau as a repower, and my only problem in 2000 hours was the oil change pump, which Beta gave me a free replacement for. I talked to a friend who bought an Olson 40 with a 20 hp Kubota-based engine. The boat was on the beach after the famous Cabo storm, so he had it towed home and the engine torn down by his trucking company mechanics. They told him it was built like a Swiss watch, and had bearings not seen in other engines under 500 hp. I did the Baja Bash in a sistership. The Kubota overheated so badly it seized. We let it cool, but more water in it, and motored another 600 miles--no permanent damage. If it had been a Yanmar, at a minimum it would have need a new head gasket.

Not all Yanmars are bad--I've motored over 500 hours on several boats with the 4JHTE engines, and they are pretty reliable as long as you give them clean fuel with no air bubbles. They also have a good cooling system and are hard to overheat.

Im sure Rod or someone else can correct me, but I hear (unsubstantiated), that the Yamnar engines are 'recreational' rated, where as the Kubotas are 'argricultural/ industrial' rated. Which relates to their 'duty cycle'. Ie Industrial rated at higher loads for a greater proportion of their life than Recreational rated engines, that are not intended to be as abused, as much of their lives.

[Compass790]

We have a yanmar engine but I would replace with Beta/kubota if buying new just because of Yanmars predatory parts pricing. However you should not need many parts for a long while if you maintain a new diesel properly.

[ramblinrod]

Originally Posted by Q Xopa

Being an agent is your opinion unbiased?

I am also a Yanmar owner, so I definitely am a biased happy Yanmar owner.

But I also know of many happy Beta owners.

Well, one can surmise what the will. All I can tell anyone is that I had serviced all brands of sailboat auxiliary diesels for years, and after developing a strong preference for Yanmar, I contacted them to become a dealer. The replacement parts business has not been nearly as lucrative as I had hopes, which is likely a testament to the reliability of the engines.

Re: Classification question by another poster. It is true that Kubota does not manufacture a marine engine. Yanmar does. Yanmar produces
Marine Recreational class engines to suit the needs of pleasure craft. They also produce Marine Commercial Engines to suit the needs of larger craft and work boats.

Having breadth and depth to the product range is not a bad thing. They can do this because they have earned a very large portion of the market, and have the sales volume to develop designs specific to narrower market segments.

[Wotname]

Originally Posted by Snowgoose35

I need to repower and will get one of these - I can get both at so close to the same price that its not a decider and they have 1 hp difference in power and 4 ft lb more torque to the Yanmar but for 0.2L / hr greater fuel consumption - its a bit more fuel but again not enough to go one way or the other.

What really matters to me is a) reliability which reports show as very good for both and b) noise and vibration

I've watched video of both and its hard to see a difference but with mobile phone video sound is always poor so has anyone direct experience of both ?

I've heard people be very impressed by the smooth running of the Beta but can't find much about the Yanmar in this respect and my experience is only of the much older 3GM series which are very noisy and rattly - will the 3YM20 be better than the older ones?

Any feedback is gratefully received

Although the specs seem similar on the brochures, I would be asking what injection system is used.

I would only choose old style mechanical injection rather than common rail EFI (if there such a choice is available).

Old style injection is way way way more tolerant of fuel contamination issues. Super clean diesel and cruising can't be used in the same sentence.

If you are willing to take extreme efforts to ensure very very clean diesel is always available, then maybe it doesn't matter.

Originally Posted by ramblinrod

The Yanmar 3YM series incorporates common rail EFI technology. Vastly superior in efficiency, reliability, and emissions reduction. You will not see black soot from the exhaust of one of these engines, coating a white transom, even if overloaded (poor prop selection).

While all you say is true, I would suggest that the reliability factor flies out the porthole as soon as one fails to keep the fuel supply ultra clean.

[gulfcoastsailor]

“An engine mount has to be removed to change the raw water impeller“

Not true on mine.

[Captain Bill]

Auxiliary parts such as starters and alternators are Not marine grade on Yanmars and are not even made by Yanmar. Mine are both made by Hitachi. They are not even painted by Yanmar. I had an exhaust elbow go bad and dump saltwater on the starter on one of my engines. It eventually failed. When I took it off and turned it over it still had the Hitachi label and part number on the bottom. I googled the part number and found that it is used on small lawn tractors from many different manufacturers including Kubota. So is the alternator. These are standard parts, not "marine grade". I have over 5000 hours on my Yanmars and the only thing I've had to do to the engines besides normal maintenance is replace the rear main seals in both engines. I have had to replace the heat exchanger on one engine which developed a leak and saltwater corroded an hole in the gasket face. While Yanmar may have an extensive service and parts network, I have had several instances where normal maintenance parts were not available anywhere in the US and had to be shipped from Japan with delays of up to 3 weeks, while sat in a boatyard running up daily fees for lack of a $20 seal, which according to Yanmar should be replaced every two years. Most of my problems with Yanmar have to do with the saildrives, which is not relevant to the OPs choice.



I have known a few people that have repowered with Betas and all of them are happy with their choice. When it comes time to repower my boat I will definitely be going with Beta.

[bounty hunter]

Originally Posted by Snowgoose35

I need to repower and will get one of these - I can get both at so close to the same price that its not a decider and they have 1 hp difference in power and 4 ft lb more torque to the Yanmar but for 0.2L / hr greater fuel consumption - its a bit more fuel but again not enough to go one way or the other.

What really matters to me is a) reliability which reports show as very good for both and b) noise and vibration

I've watched video of both and its hard to see a difference but with mobile phone video sound is always poor so has anyone direct experience of both ?

I've heard people be very impressed by the smooth running of the Beta but can't find much about the Yanmar in this respect and my experience is only of the much older 3GM series which are very noisy and rattly - will the 3YM20 be better than the older ones?

Any feedback is gratefully received

does it matter to you that the Beta '20' only outputs 17-odd hp? whereas the yanmar is 21hp

the Beta '25' is a more direct comparison in terms of output

[ramblinrod]

Originally Posted by Wotname

Although the specs seem similar on the brochures, I would be asking what injection system is used.

I would only choose old style mechanical injection rather than common rail EFI (if there such a choice is available).

Old style injection is way way way more tolerant of fuel contamination issues. Super clean diesel and cruising can't be used in the same sentence.

If you are willing to take extreme efforts to ensure very very clean diesel is always available, then maybe it doesn't matter.



While all you say is true, I would suggest that the reliability factor flies out the porthole as soon as one fails to keep the fuel supply ultra clean.

Clean air and fuel is important to every ICE on the planet. I don’t 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.

[a64pilot]

No, it has everything to do with fuel cleanliness and how long an injector will last.
Why a common rail needs perfectly clean fuel is due to fuel pressure, they run on average about 30,000 PSI. An average mechanical engine runs at about 800 PSI.
This very high fuel pressure will take any particle and actually cut the nozzle of an injector like a water jet cuts steel.
Couple that with the fact that a Common Rail’s injector tip hole size is so incredibly small means it’s even more easily damaged.
It takes insanely high pressure for the Magic of Common Rail to work, like multiple injection events per cylinder firing etc. one reason they can run so smooth and idle so quiet is the a common rail can inject a tiny pre-shot of fuel early to get a fire going so that the main injection event burns smoothly and doesn’t “Diesel”.

Jamming the pressure up so high means you can get all the fuel needed in a very short time, plus as each injector is individually managed and fired also enables things like adjustable timing to be simply a matter of programming, and lots of other magic like skipping cylinders and limp home modes etc.

Common Rails are a completely new type of Diesel and can do things like make Diesels real hot rods and make them as quiet as a gas motor. Just listen to any new Diesel pickup truck.

However it requires incredibly clean fuel, or you will be changing fuel injectors, and sit down when you price them, because they are mechanical marvels, that doesn’t come cheap.

[FlyingScot]

Originally Posted by bounty hunter

does it matter to you that the Beta '20' only outputs 17-odd hp? whereas the yanmar is 21hp

the Beta '25' is a more direct comparison in terms of output

I don't see that in the specs.
Yanmar 21bhp vs Beta 20bhp. If you referring to maximum continuous power, Yanmar doesn't allow continuous full throttle operation either. This model seems to want 100 rpm less. My 3YM30 wants 200 rpm less.

[FlyingScot]

Originally Posted by a64pilot

No, it has everything to do with fuel cleanliness and how long an injector will last.
Why a common rail needs perfectly clean fuel is due to fuel pressure, they run on average about 30,000 PSI. An average mechanical engine runs at about 800 PSI.
This very high fuel pressure will take any particle and actually cut the nozzle of an injector like a water jet cuts steel.
Couple that with the fact that a Common Rail’s injector tip hole size is so incredibly small means it’s even more easily damaged.
It takes insanely high pressure for the Magic of Common Rail to work, like multiple injection events per cylinder firing etc. one reason they can run so smooth and idle so quiet is the a common rail can inject a tiny pre-shot of fuel early to get a fire going so that the main injection event burns smoothly and doesn’t “Diesel”.

Jamming the pressure up so high means you can get all the fuel needed in a very short time, plus as each injector is individually managed and fired also enables things like adjustable timing to be simply a matter of programming, and lots of other magic like skipping cylinders and limp home modes etc.

Common Rails are a completely new type of Diesel and can do things like make Diesels real hot rods and make them as quiet as a gas motor. Just listen to any new Diesel pickup truck.

However it requires incredibly clean fuel, or you will be changing fuel injectors, and sit down when you price them, because they are mechanical marvels, that doesn’t come cheap.

Both the Yanmar 3YM20 and the Beta 20 are indirect injection.
http://www.betamarineengines.com/dow...C-SOM-0314.pdf
https://www.yanmarmarine.com/theme/y...heet_3YM20.pdf

I would not want common rail on a sailboat. The increased efficiency doesn't offset the complexity and increased difficulty of service.

[Cheechako]

Compare RPM vs HP curves also. Yanmars are famous for rating at high rpm, thus making a lower HP engine appear to be higher HP. (Well... that's one way of saying it) I don't know about the Beta. I hated running my 3600 rpm Yanmars at 3400 rpm.