L275 alternator not charging. Diagnose & overhaul questions

[timsch]

Looking at my alternator today and following the service manual check as shown in Fig.68. My connector is flipped from the way it's shown below, with the vertical one on the left side, so I looked at the wiring diagram in the manual that shows the wiring to these connectors and see that I'm supposed to be checking the one that goes to the black wire and the one that goes to the green/white wire. Those measured 0V. I checked the one to black vs the one to white/blue for the heck of it and I got 6.3V. Battery voltage measures 12.5V, and the same 12.5 measured from the alternator (+) connection to an engine ground.

My knowledge of overhauling these things only goes as far as checking brushes and cleaning the rotor. Any pointers on what these readings might indicate will be appreciated. No telling how long since it's been apart, if ever. 1500 hours on it.

 

[Russell King]

I suggest you take it to an alternator repair shop and get it tested and rebuilt if that is needed. The regulator is (probably) external and underneath the dash (cowl).

On my L185 the alternator was not repairable but they provided a rebuilt alternator and I got the regulator from the dealer.

 

[timsch]

I removed and started disassembling the alternator today to do an inspection - at least look at the brushes. It was filthy. I was not able to get it all of the way apart, unfortunately. I'm getting separation this far, but it's hanging up. Not sure of what is holding it , but didn't want to force it.

From this, I'm guessing the bearing would may be stuck. Anyone dealt with this before?

Here's the end view:

 

[Russell King]

I have had similar issues with alternators and it ends up the bearing is stuck to the shaft AND the housing. I got them apart eventually but it was tedious.

From the looks of what you show, it may not be repairable.

Good luck though!

 

[timsch]

Maybe not, but far be it from me not to give it a shot. Did you do anything other than tapping and prying away on it? Was the bearing in that recessed area of that end cover? If so, I could probably spray some penetrating fluid down in there.

 

[Russell King]

It has been some time since I wanted to repair an alternator so I can’t remember exactly what I did!

But yes, it was the bearing in the recess that was stuck. I imagine that at that time in my life, I would have just hit it and wiggled the rotor and used WD-40 in copious amounts.

You might try to secure the stator through the mounting and adjusting bolts and then trying to attach the rotor shaft to a bar and try to jack or pry them apart. I vaguely remember having alternators hung from the rafters somehow and pulling on the stator.

 

[Hugo Habicht]

From this, I'm guessing the bearing would may be stuck. Anyone dealt with this before?

Remove the front bearing from front housing, put the front housing back and turn the nut (1) over a slieve as a spacer to pull the rotor out.

 

[William1]

Slide hammer to pull the rotor out.
I'm guessing but a plastic hammer against the bolts may pop the windings out. I assume you got the brush holder out already.

 

[timsch]

No, I haven't made it to the brush holder. If I'm not mistaken, it's attached to that larger stud shown in the bottom pic. Between my slide hammer and Hugo's suggestion, it should come out.

 

[William1]

No, I haven't made it to the brush holder. If I'm not mistaken, it's attached to that larger stud shown in the bottom pic. Between my slide hammer and Hugo's suggestion, it should come out.

Should work. As you tighten the nut, rap on the shaft/nut with a plastic hammer, the shock will aid in breaking the bond. Don't just crank down on the nut.

 

[lmichael]

Brings back memories. When I was a Cadillac Dealer Tech back in late 60s/early 70s I was still seeing cars in my stalls from as old as the late 40s up to brand new. If I rebuilt one alternator (Delcotron)I must have rebuilt well over 100, and same goes for the old "Generators". Starters, water pumps and so on. Back in those days you didn't "replace" you rebuilt.

 

[lynnmor]

Back in those days you didn't "replace" you rebuilt.

This new generation drives me crazy, Throwing a good unit away when it only needed a small part borders on insanity.

 

[Russell King]

Remove the front bearing from front housing, put the front housing back and turn the nut (1) over a slieve as a spacer to pull the rotor out.

Much more elegant removal process than my youthful procedures!

 

[bird dogger]

@timsch Once you get the alternator apart, there's many tutorials (both youtube and written) on checking & testing the alternator parts individually and as a whole working unit. For example: a good general cleaning, making sure the isolators are in good shape, testing the diodes in the diode plate, etc.

A friend and I encountered a similar issue with an L2550 alternator and the tractor's charging system.
You can see that write up here. The old alternator definitely needed a good cleaning and checking. The owner opted to purchace a new alternator. But with the new one installed, the charging system still was not up to speed. The voltage regulator also needed some attention and adjustment. See our fix in that other thread mentioned.

A new alternator from Kubota was outlandish in price. We found one online for a fraction of that price and barely more than if we had started to replace diode plates, bearings, etc. on the original alternator.
It looks like a replacement for your's can be had for $100 from Iron Wing as just one example. Something to keep in mind if you have to start throwing too many parts at yours.

But don't be afraid to inspect your voltage regulator if its similar to the one I worked on as mentioned above. Your symptoms could also be a combination of issues related to both the alternator and its regulator.

 

[Hugo Habicht]

Much more elegant removal process than my youthful procedures!

Thank you, but your method with the levers is possibly easier and faster and I remember vaguely having it done this way too. I try "smooth" (*) action first before applying hard hammering. But the latter is often required.

WD40 or similar oil is always very helpful, thank you for mentioning that!

(*) quotation marks borrowed from @Runs With Scissors

 

[lmichael]

Where do you find parts to rebuild them at?

 

[Hugo Habicht]

Where do you find parts to rebuild them at?

For example: Generator spare parts online shop

 

[lmichael]

Not exactly in my neck of the woods

 

[Hugo Habicht]

Not exactly in my neck of the woods

I know ...

Was only an example, but I am pretty sure that similar web shops must exist in the USA. If anything else fails you can use a forwarding company, I used one a few times to get Kubota (or other) parts from the USA to Europe. Since those parts are pretty small and light, shipping cost should be reasonable.

 

[lmichael]

So a quick search shows pretty much nothing for places to buy the parts. So in all likelihood if/when the day comes I need it, I'll likely just order one from DB Electrical. I know a lot of purists hate the aftermarket stuff. But honestly I've been buying their products for a VERY long time now and whether starters or alternators I've never had one give me any issue at all. Actually my Kubota is running a DB Electrical starter I installed before I discovered it's not the starters that "fail" but the need for a "helper" relay.
I think somewhere I still have the old starter disassembled but I have to say, the workmanship and quality level of the DB seems as good or dare I say better than the OEM.
I've put there stuff in a couple Toyotas I've owned, an old Saturn SL2 I had (that got rear ended and totaled by a Jeep Grand Cherokee) that car had a DB starter and alternator. Both were doing great for many thousands of miles. Until it got "clocked" by that Jeep at about 210k miles