Yanmar engine issues

[Fr J Hackett]

I would be looking at whether the boat / alternator is fitted with a smart regulator, it sounds like it is relying on an internal regulator.

Balmar Voltage Regulation Technology - Balmar

See stage 1 "Start delay"

 

[greeny]

Not read all the previous posts in detail but think I've got the basics. Any reason why you couldn't remove the belt for a short while and test engine without the alternator? Or is there some technical reason why this is not possible.

 

[Rhubarb]

Not read all the previous posts in detail but think I've got the basics. Any reason why you couldn't remove the belt for a short while and test engine without the alternator? Or is there some technical reason why this is not possible.

Greeny, you’re bang on the money!
When the alternator is disconnected the engine performs perfectly. Ie starts immediately and can go to full revs 3600 without difficulty. So it is not a fuel, air or drive belt problem.

 

[Rhubarb]

I would be looking at whether the boat / alternator is fitted with a smart regulator, it sounds like it is relying on an internal regulator.

Balmar Voltage Regulation Technology - Balmar

See stage 1 "Start delay"

It’s the standard Hitachi alternator as supplied with the engine. All of which is still under warranty, so I’m interested if anyone else has the problem?

 

[burgundyben]

Greeny, you’re bang on the money!
When the alternator is disconnected the engine performs perfectly. Ie starts immediately and can go to full revs 3600 without difficulty. So it is not a fuel, air or drive belt problem.

Is it an electronically controlled engine or one with a mechanical fuel injection pump?

(I work in engine development and power electronics, I have a pretty good understanding of these things)

 

[Rhubarb]

Just watched yr video -I think it's quite tough on the engine to start from cold at full throttle (I assume it was from cold & you don't get this problem on a hot start?) What happens if you start with the lever vertical, then after say 30s gently inch it up?

Hi Adjag,

Can I enquire how you keep your boat? Ie are you attached to shore power most of the time?

We keep ours on a swinging mooring and anchor a lot. The Fridge can therefore pull our domestic batteries down to 70% over a couple of days and that is when the problems really show up. Ie the batteries are asking the alternator for everything it has got.
Even once the engine has revved up, if you try to use it for manoeuvring the response to the throttle is sluggish ie you need to apply the power 10 seconds before it is needed. This is really not good in any close quarters situation.

 

[Rhubarb]

Is it an electronically controlled engine or one with a mechanical fuel injection pump?

(I work in engine development and power electronics, I have a pretty good understanding of these things)

Hi BurgendyBen,

it’s mechanically controlled and I believe that is the root of the problem. The ‘tail is wagging the dog’ here. The alternator only knows what the batteries are demanding and is blissfully unaware as to what the engine is being asked to do / is doing. Ie the secondary system (the alternator) is interfering with the primary system (the drive system). An electronic control system would be the obvious solution but Yanmar didn’t fit one.

 

[greeny]

Greeny, you’re bang on the money!
When the alternator is disconnected the engine performs perfectly. Ie starts immediately and can go to full revs 3600 without difficulty. So it is not a fuel, air or drive belt problem.

Not really, could still be a fuel problem. Talk with Burgendyben, he sounds more knowledgeable than I am.

 

[Rhubarb]

Not really, could still be a fuel problem. Talk with Burgendyben, he sounds more knowledgeable than I am.

Can you clarify, how it “could still be a fuel problem “ when the engine performs as expected when the alternator is disconnected?

 

[Fr J Hackett]

It's clearly an alternator regulation problem.

 

[Fr J Hackett]

It’s the standard Hitachi alternator as supplied with the engine. All of which is still under warranty, so I’m interested if anyone else has the problem?

regardless of whether anyone else has a problem or not as they might have recognised the issue it's not a problem and changed to a smart regulator. By disconnecting the alternator you removed the additional loading on the engine at start up. When the alternator is connected it takes time for its internal regulator to sense the battery condition and reduce the output when the battery is fully or close to fully charged. It is not particularly detrimental but can easily be rectified by removing the internal regulation and fitting a smart regulator. I don't think in fact I am pretty sure this is not a warranty issue. There is nothing fundamentally wrong but there is a better way of regulating your high output alternator.

 

[Adjag]

Hi Adjag,

Can I enquire how you keep your boat? Ie are you attached to shore power most of the time?

We keep ours on a swinging mooring and anchor a lot. The Fridge can therefore pull our domestic batteries down to 70% over a couple of days and that is when the problems really show up. Ie the batteries are asking the alternator for everything it has got.
Even once the engine has revved up, if you try to use it for manoeuvring the response to the throttle is sluggish ie you need to apply the power 10 seconds before it is needed. This is really not good in any close quarters situation.

Hi
We keep it in a marina on shorepower, even then it's a bit sluggish for first 30s or so. If we've been anchored a for a few days then I need to leave it idling (or fast 1000rpm idle when it'll do it) for maybe 2mins. It's never bothered me as I like to let the engine warm up before using it in anger. But, unlike you, when it's warm it gives power straightaway eg other day I misjudged sailing past a bouy (engine had been off for abt 3hrs) and got power straightaway (thank goodness)

 

[burgundyben]

Hmm. Curious.

I'll think about it.

 

[Rhubarb]

It's clearly an alternator regulation problem.

I wouldn’t disagree. But it’s the standard Yanmar setup ( less than 2 years old) and allegedly there is nothing wrong with the alternator itself.
Barrus (Yanmar’s Uk agent) say that there is nothing wrong with the Setup and blame Jeaneau for putting too many batteries downstream of the alternator - apparently it’s only for charging the engine battery! Makes you wonder why they fit a 125amp alternator as standard.
That’s why I’m interested if anyone else with the 3ym20/125a alternator has similar problems, because I do wonder if it’s a voltage regulation problem on our alternator.

 

[Fr J Hackett]

I wouldn’t disagree. But it’s the standard Yanmar setup ( less than 2 years old) and allegedly there is nothing wrong with the alternator itself.
Barrus (Yanmar’s Uk agent) say that there is nothing wrong with the Setup and blame Jeaneau for putting too many batteries downstream of the alternator - apparently it’s only for charging the engine battery! Makes you wonder why they fit a 125amp alternator as standard.
That’s why I’m interested if anyone else with the 3ym20/125a alternator has similar problems, because I do wonder if it’s a voltage regulation problem on our alternator.

Well it's far to large for just charging the starter battery so Barrus are trying to deflect a little a however they are correct that there is nothing wrong with the set up and as I have said I don't think you are going to get any change out of Jeaneau. If you want to change and remove the delay in achieving max revs then a smart alternator is the way to go it will have the added benefit of reducing alternator belt wear. Even at 1000 revs you should have some drive from the engine.

 

[Rhubarb]

Hi
We keep it in a marina on shorepower, even then it's a bit sluggish for first 30s or so. If we've been anchored a for a few days then I need to leave it idling (or fast 1000rpm idle when it'll do it) for maybe 2mins. It's never bothered me as I like to let the engine warm up before using it in anger. But, unlike you, when it's warm it gives power straightaway eg other day I misjudged sailing past a bouy (engine had been off for abt 3hrs) and got power straightaway (thank goodness)

Can I enquire how many battery banks and batteries you have? We have 3 banks and 5 batteries. 1 engine, 2 domestic, 2 windlass.

Could I be so bold as to ask you to disconnect your shore power and run down your domestic batteries to less than 80% and time the startup?

Like you, we like to warm the engine up before use, but this has hidden the problem for some time and unlike you we have no confidence that if we misjudged our position that a quick engine start and burst of power would happen/save us.

As no one else seems to be complaining we wonder if there is a problem in our individual boat.

 

[Rhubarb]

Well it's far to large for just charging the starter battery so Barrus are trying to deflect a little a however they are correct that there is nothing wrong with the set up and as I have said I don't think you are going to get any change out of Jeaneau. If you want to change and remove the delay in achieving max revs then a smart alternator is the way to go it will have the added benefit of reducing alternator belt wear. Even at 1000 revs you should have some drive from the engine.

You seem to be implying that the problem is acceptable? Both Barrus and Jeaneau have agreed that it is not expected or acceptable performance. As the boat / engine is under warranty, why do you think it is my problem to fix?

 

[greeny]

Not really, could still be a fuel problem. Talk with Burgendyben, he sounds more knowledgeable than I am.

Can you clarify, how it “could still be a fuel problem “ when the engine performs as expected when the alternator is disconnected?

Because an engine with no load or low load will rev it's b******s off using less fuel than an engine on load trying to achieve similar revs. Putting more load on the engine i.e. re connecting the alternator which sounds like a large lump of load extra and there may not be enough fuel going in to fuel it. That's my understanding but I may be wrong. That's why I said talk to Ben. However I do agree with you that it sounds like the alternator is too big for the engine. My Ben 323 had a 3ym20 but with a 60 amp alt. Never had a problem. At least not one I ever noticed.

 

[jwilson]

It's still hard to believe that a single battery charging alternator is swallowing most of the power from a 18 hp diesel.

Will it quickly give a good burst of revs and power to the prop in gear with the belt removed? Not just rev in neutral.

 

[Tranona]

Can I enquire how many battery banks and batteries you have? We have 3 banks and 5 batteries. 1 engine, 2 domestic, 2 windlass.

Could I be so bold as to ask you to disconnect your shore power and run down your domestic batteries to less than 80% and time the startup?

Like you, we like to warm the engine up before use, but this has hidden the problem for some time and unlike you we have no confidence that if we misjudged our position that a quick engine start and burst of power would happen/save us.

As no one else seems to be complaining we wonder if there is a problem in our individual boat.

Perhaps it is something to do with your charge splitter. I had a similar setup with my Bavaria 33, albeit with a 30 hp engine. 5*95ah batteries in 3 banks, one for engine, 3 for house and one for bow thruster/windlass. Volvo D1 30 with a 115amp alternator charging through a 3 way Cristec splitter. Never any problem such as you describe because, I think the splitter first charges the start battery (which takes minutes, or even seconds, then the house and then the forward battery, In reality the house is the only one that really demands a big charge. Do you have a battery monitor which will tell you how much is going into the house bank on start up?

As a sort of aside Yanmar used to fit an alternator cutout for startup on the 1GM when fitted with a saildrive because the added drag of the saildrive oil was enough to make starting and cold running difficult. Maybe it is something to do with the fuelling at low revs and the minimal power the engine produces that tips it over the edge compared with a Volvo. BTW I never consciously needed the glow plugs on the Volvo as it always started immediately after turning on even in UK winter weather.