Internal Regulated Alternator Conversion

[TX mower]

This not for everyone, maybe of interest if you need to replace your voltage regulator, alternator, acquire a tractor with major wiring kludges, or just like simplified electrics.

This all in the context of a 336D but some (many?) other Yanmar models are identical or very similar - up to you to determine similarities or differences and adapt as required for your specific situation. I have done this mod on my Yanmar and it works perfectly. Even if doing this on a 336D it's up to you to verify everything matches your tractor.

Background

• The 336D shares the 35 Amp alternator and external mechanical voltage regulator found in several '60s and '70s Datsun/Nissan cars/small pickups.
• Datsun/Nissan later went to an internally regulated (IR) alternator of identical capacity, yielding simplified wiring and more reliable operation (the IR alternator uses a solid-state regulator system)
• The Datsun 1200 Club Forum has popularized and fully documented the upgrade from the older alternator+mechanical regulator system to the more modern IR Alternator system
• This post builds on that information and documents my implementation on the Yanmar 336D application

Cost and Fitment

• As of this date the price of the Hitachi LR-135 IR Alternator I used is $47.79 including the core charge but not including shipping from RockAuto (note too that 5% off codes for RockAuto are widely available via internet search)
• That price is competitive if not better than many of the Yanmar voltage regulator only replacements or alternator only replacements, while serving to replace both the alternator and the voltage regulator
• That's for a Hitachi alternator remanufactured by AC Delco and shipped in AC Delco packaging with 24-month warranty
• The alternator is complete with pulley and for me was an exact physical match bolt-on with zero modification required to any of my Yanmar mounting brackets / adjuster; the threaded adjuster-bolt hole in the alternator casting was exactly as OEM Yanmar
• See this link for the RockAuto detail page including dimensional data to verify mounting fitment for your situation RockAuto ACDELCO 3341571 = Hitachi LR-135
• In addition to the alternator, the mod requires a few inches of wire and 4 standard crimp-on male 1/4" blade connectors (to DIY two 'jumpers' installed at the OEM Yanmar 6-blade voltage regulator harness connector upon removal of the OEM regulator)
• Yes, the OEM Yanmar 336D 'charging warning lamp' will continue to function exactly as original.

Instructions
See and study the attached Figures 1 through 4 .... post-up if you've any questions.

 

[TX mower]

Going Overboard

For me, the above mod was prompted by an 'iffy' OEM voltage regulator. I also was dealing with very 'crispy' wiring insulation throughout my 336D.

I'm an inveterate long-time car and motorcycle modifier with fairly decent experience with electrical systems. I like 'em KISS whenever possible.

In 30 years of ownership/use of my 336D I've never worked in the dark, never used any of the lights, never touched the horn.

So, after 'proving' the IR mod described above with my OEM harness and jumpers I undertook a total electrical system overhaul on my tractor, including installation of mechanical gauges for water temp and oil pressure (eliminating the electrical sending units and 'idiot lights' for those functions while keeping the 'charge lamp' warning light).

It's amazing how simple and clean the wiring can be on a tractor when all it needs to do is start the engine and charge the battery (while retaining all the original starting-safety interlocks).

Compare this to Figure 1 (OEM wiring) in the post above:

 

[California]

... I have done this mod on my Yanmar and it works perfectly.

The 336D shares the 35 Amp alternator and external mechanical voltage regulator found in several '60s and '70s Datsun/Nissan cars/small pickups.

Datsun/Nissan later went to an internally regulated (IR) alternator of identical capacity, yielding simplified wiring and more reliable operation (the IR alternator uses a solid-state regulator system)

The Datsun 1200 Club Forum has popularized and fully documented the upgrade from the older alternator+mechanical regulator system to the more modern IR Alternator system

Thank you! This is a new and valuable addition to the 'common body of knowledge' this forum preserves. When I bought the YM240 I stupidly killed the old mechanical regulator by pressure-washing a solid mud mud-dauber nest out from under it. I didn't realize it wasn't water tight, and had big resistors mounted externally beneath it. That smoked the alternator. All user error, not a Yanmar fault. I read here that '72 Datsun 35 amp alternator and regulator were identical so I bought those, I think $29 and $18 at the time. No problems since. Incidentally Datsun's Air Conditioning version alternator for that year is 50 amp but it's fatter so it needs a longer adjustment strap and longer belt. Replacing like for like is simpler.

I wish I had known of your preferable upgrade back then.

That's good to know! :thumbsup:

 

[TX mower]

.... Incidentally Datsun's Air Conditioning version alternator for that year is 50 amp but it's fatter so it needs a longer adjustment strap and longer belt. ...

Building on that, here's the spec page for the later LR-150 (50 amp) alternator with some dimensional data if anyone wants to pursue a higher-output IR Alternator upgrade: RockAuto ACDELCO 3341578 = Hitachi LR-150

It's actually a few buck less than the 35 Amp version, and though the mounting foot spacing, pulley offset and pulley diameter appear the same as the 35A unit I used, there may be other (overall O.D.?) dimensions that require additional mounting mods of the sort you mention.

Even if one seeks to add aux lighting, these days I'm not sure if more than 35A is necessary given the wide availability of very low-current-demand LED lighting. But in any case, there's a higher output IR Alternator option if anyone is interested.

Conveniently, Hitachi used the "LT" prefix designating the older externally regulated alternators (LT-135, LT-150) and "LR" for the physically similar Internally Regulated counterparts (LR-135, LR-150).
_____

Aside .... mildly interesting to me is the lack of any 'master wiring protection' in the Yanmar applications (at least none I've found on my 336D). I.e. I've not found evidence of a fusible link or fuse on the main 35A alternator feeds in the OEM 336D application.

Maybe not strictly necessary, I suppose the fire-risk is low on a diesel tractor, but as a matter of habit I included appropriate fusible links on the main feeds when I built my new replacement harness (shown in the figure in post 2 above). At ~$4.50 each from my local NAPA, just cheap insurance, IMHO, and they're a zero-maintenance / extremely robust item. They'll harmlessly melt IF there's a ground-fault on either of the main circuits - acting much faster than a fuse to hopefully prevent trauma to anything else.

 

[California]

I've not found evidence of a fusible link or fuse on the main 35A alternator feeds in the OEM 336D application.

Maybe not strictly necessary, I suppose the fire-risk is low on a diesel tractor, but as a matter of habit I included appropriate fusible links on the main feeds when I built my new replacement harness ... just cheap insurance

Very good advice.

I turned sharp, and the hitch pinched the lampcord going back to my watering-trailer pump. All of the cord from the battery to the back burned off the insulation instantly and glowed fiery red.

Luckily I was wearing gloves so I just yanked the burning wires to get the alligator clips off the battery.

... A moment of pure panic - "Am I going to burn up the whole tractor before i can even climb off it?"

I added a fuse in the next iteration.

 

[kenmac]

Re: Going Overboard

For me, the above mod was prompted by an 'iffy' OEM voltage regulator. I also was dealing with very 'crispy' wiring insulation throughout my 336D.

I'm an inveterate long-time car and motorcycle modifier with fairly decent experience with electrical systems. I like 'em KISS whenever possible.

In 30 years of ownership/use of my 336D I've never worked in the dark, never used any of the lights, never touched the horn.

So, after 'proving' the IR mod described above with my OEM harness and jumpers I undertook a total electrical system overhaul on my tractor, including installation of mechanical gauges for water temp and oil pressure (eliminating the electrical sending units and 'idiot lights' for those functions while keeping the 'charge lamp' warning light).

It's amazing how simple and clean the wiring can be on a tractor when all it needs to do is start the engine and charge the battery (while retaining all the original starting-safety interlocks).

Compare this to Figure 1 (OEM wiring) in the post above:

View attachment 574891

So, with this diagram, I will not have to do all the jumper wires like you show in Fig.____2 alternator mod ?
Or, Am I still going to have to add all the jumper wires at the Voltage regulator like is shown in fig. _____2 ?

Is the T connector already being used on the OEM alternator, or will I have to make just a 2 wire connector there ?

Just ordered the rock auto alternator. I'll see if I can get it wired up when it comes in.

Thanks for the info ! Hopefully I can figure it all out

 

[TX mower]

^ Great anecdote, California, though I'm sure not fun at the time.

It's unfortunate that too many folks have no comprehension of (or respect for) the tremendous, and tremendously dangerous, high-current that a 12VDC automotive battery is capable of dumping given a good path to ground (including the human body, with resultant very serious burn potential).

 

[Sawyer Rob]

I've been putting "one wire" alternators on tractors for many years... It's a easy low priced conversion...

SR

 

[TX mower]

Re: Going Overboard

So, with this diagram, I will not have to do all the jumper wires like you show in Fig.____2 alternator mod ?
Or, Am I still going to have to add all the jumper wires at the Voltage regulator like is shown in fig. _____2 ?

The "Going Overboard" schematic in post 2 is a complete custom replacement DIY-from-scratch harness which as shown eliminates all of the OEM lighting, electric gauges and horn.

For your 'typical' situation I suggest you please ignore that and after confirming that your 3110D wiring matches my 336D, follow the instructions in post 1 (including jumpers).

Please understand I'm trying to be very careful, and asking readers to do the same, to avoid pitfalls for everyone. Though I suspect many Yanmars are similar I do not know that the wiring colors or pin-assignments, particularly at the voltage regulator harness connector, are all identical.

Is the T connector already being used on the OEM alternator, or will I have to make just a 2 wire connector there ?

Assuming that your 3110D matches my 336D, you'll find your alternator harness already has a "T" connector with the "S" and "L" wires correctly situated - just plug it into the replacement IR alternator.

Just ordered the rock auto alternator. I'll see if I can get it wired up when it comes in.

Thanks for the info ! Hopefully I can figure it all out

Drop me a PM I'll try to get back with you ASAP to try to help if needed. I'll be glad to reply by phone if you include a number and OK 'call-time window'.

 

[kenmac]

Re: Going Overboard

For me, the above mod was prompted by an 'iffy' OEM voltage regulator. I also was dealing with very 'crispy' wiring insulation throughout my 336D.

I'm an inveterate long-time car and motorcycle modifier with fairly decent experience with electrical systems. I like 'em KISS whenever possible.

In 30 years of ownership/use of my 336D I've never worked in the dark, never used any of the lights, never touched the horn.

So, after 'proving' the IR mod described above with my OEM harness and jumpers I undertook a total electrical system overhaul on my tractor, including installation of mechanical gauges for water temp and oil pressure (eliminating the electrical sending units and 'idiot lights' for those functions while keeping the 'charge lamp' warning light).

It's amazing how simple and clean the wiring can be on a tractor when all it needs to do is start the engine and charge the battery (while retaining all the original starting-safety interlocks).

Compare this to Figure 1 (OEM wiring) in the post above:

View attachment 574891

Guess I'm confused. Do I follow this diagram above, (ym 336 simplified wiring) or follow the others you posted Fig 1 fig 2 fig 3 fig 4 ?

Thanks