The Kubota L2550 that slipped through my fingers!!

[bird dogger]

But not before we fixed a couple of small issues.

Last spring, a close friend and former co-worker suffered a serious stroke on his rural 28 acre homesite. It became evident he and his wife wouldn’t be able to continue living there. With their two children living out of state, we’ve helped out as much as we can where/when needed.

Through the summer, a couple of us friends helped haul and store goods and tools, equipment, etc. My locksmith buddy and I re-keyed all the entry doors & dead bolts, shed doors, etc. since the place was now vacant. I had volunteered to service his tractor and get it running. The battery was dead and the charging circuit wasn’t functioning. I told the daughter that should they decide to sell the tractor separately, I’d be very interested in having first shot at buying it. Along with my tractor and the L2550 together, they made short work of the mowing and cleaning up the huge lot before listing the property.

Here's some thumbnail pics of this very nice L2550 tractor:


One of the good friends that helped with the mowing and other tasks asked if I knew what the status of their tractor would be. I told him I already had dibs on it if they decided to sell it separately. He stated he would also be very interested in it.

As nice as this L2550 is…..I really didn’t need another tractor. When the family finally decided to sell the tractor outright, I decided to pass on buying it, knowing it would go to this other good friend of the family. I told the happy buyer if he ever decided to sell it, it had to go to me at that time. LOL! He agreed.

We hauled the L2550 to my place to figure out and fix the charging system issue. The battery wouldn’t hold a charge overnight. With the tractor running, the alternator essentially showed no output voltage. Both the alternator and voltage regulator looked original to the tractor. We suspected either a bad rectifier module in the alternator or possibly a voltage regulator issue being the culprit.

There were also a couple of loose wires hanging from the wire loom right below the voltage regulator. Hmmnn….? The voltage regulator was extremely clean inside. We burnished the contacts, ohmed out the coils & resistor, found no shorts to ground in the wiring, etc. So, it went back together and back onto the tractor.


I disassembled the alternator to thoroughly check the rectifier diodes. They were all good. There were no shorts from the stator coil to ground. Same for the rotor’s coil to ground. However, there was a thick buildup of brush graphite & gunk on the two slip rings from the alternator brushes. The brush holders also needed a good cleaning to allow the brushes to move freely. The brushes also looked well worn to the point where there was very little or no contact pressure on the slip rings from the springs in the brush holders.


All cleaned up and put back together, we thought it may work again until new parts could be located. But at rated engine rpm, the output voltage was only equal to the battery voltage, or no charging voltage at all… or negligible at best.

A wiring diagram showed one of the two loose wires had to have been for an original battery’s electrolyte level sensor. It’s unclear if the other wire was also associated with that sensor. But they didn’t appear to be associated with the charging circuit.

Since a new rectifier & brush holder assembly was almost as expensive as a new aftermarket alternator, a replacement alternator was ordered. The replacement alternator arrived and was installed with no issues. We crossed our fingers for the live test. Again, no cigar. There was still no apparent charging voltage above battery voltage. All the wiring, connections, and grounds had been checked and found good. We decided to call it a day and regroup again later.

That night I started thinking about the voltage regulator and how they were originally tested and the voltage level set. I remembered helping another buddy do that on his old truck way back when. I have some old truck motor repair books and found the section on regulator setup, testing and repair. Woohoo!! After boning up on the topic again, I was hoping to find an adjusting screw on the voltage regulator relay to re-set the voltage….as in crank it up a little.

Stay tuned for the "Rest of the Story"

 

[bird dogger]

Another option was to bend the tab on the voltage regulator coil to increase spring tension on the coil’s clapper arm.

Bright and early the next morning: I found the regulator had no adjusting screw for setting the voltage level. And the tab to be bent for more spring pressure looked too stout to be safely bent without the proper tool, or at all. If the tractor belonged to me, I would have tried it with a needle nose pliars. But I didn’t want to damage it either, considering the tab could break off completely. The yellow arrow points to the tab that could be bent to adjust the voltage.


With the tractor running, you could feel the coils buzzing even though you really couldn’t see them moving. Except when you turned the key off or on, could you see one contact operate like it should.

This time, though, I cleaned between the clapper arms, tension springs, etc. Also, anything that was a pivot point was cleaned.

Now with a meter on the battery, the voltage jumped up to 13 volts at rated rpm! Not the best, but at least things were starting to work! Still, there’s the question of how to increase the spring tension on the voltage level coil to try bump up the charging voltage. The book says to be careful using very minor tweaking of that tab for the desired end result.

Then it occurred to me to just put a thin shim between the tab and the spring tensioner for testing purposes. Some brown builder’s paper was handy. Doubled over once, then twice for 4 layers thickness was placed between the tab and the spring. Starting the tractor and increasing the rpm had the voltage reading 16 VDC and climbing! Pulling the paper out had the voltage drop back to 13 VDC. Reduced to a single thickness of paper for a shim, the voltage output was a steady 13.8 to 13.9 volts depending on the rpms. Perfect!!


I called my buddy and told him I fixed your tractor’s charging circuit but you won’t believe me if I tell you how. He insisted, so I told him I fixed it with a piece of paper! He didn’t believe me….but said he'd be coming over in a few minutes to see for himself.

He was amazed that such a small change in the spring tension from that paper shim could make that big of a difference. Maybe that spring steel had lost a little tension from all the buzzing over the 2400 tractor hours? Or maybe a little wear in all its joints caused less tension? Or a combination of those things? Who knows??

But since it was now charging at 13 volts without the shim, he decided to leave it like that to see if that would suffice for now. If it doesn’t work out, we’ll adjust that tab later….. or just add a shim again for more spring tension.

The battery also quit draining overnight now that we had everything functioning properly again. The original alternator will be kept as an emergency spare. Since this tractor lacked the optional package of warning lights for the dash, I think a little LED battery voltage level indicator will be added to it in the near future.

The original owner had been very particular with his tractor (other than the charging issue which may have only recently occurred) as there isn’t one leaky hydraulic fitting. No oil leaks at all, anywhere!! Only a little wear in the paint in the operator’s station from shoes on the floorboard. And the seat had been replaced.

When you turn the key, the engine is running instantly! A coat of wax on the original paint would have it looking showroom floor ready again!

Since my buddy will be using it occasionally in the wintertime, I also made a set of winter front covers for it before we hauled his tractor to its new home. He’s extremely pleased with the tractor now!!



Even though I let it slip through my fingers, the tractor is where it belongs……..for now, anyway!

I'm hoping he'll keep up his end of the bargain if he ever decides to sell it. I suspect I'll be in a retirement home at that point. Maybe I'd have someone trailer it past the window so I could just look at it!

 

[jyoutz]

That’s a nice looking old machine. Glad that you got it running.

 

[bird dogger]

That’s a nice looking old machine. Glad that you got it running.

Thanks, and yes it is very nice older machine. I think original owner actually purchased it right around 1990. So, 30 plus years ago. It was really tempting not to pass it up!

But the new owner has a nice lakeside cabin on a prime walleye lake. I forsee a great fishing weekend in the near future!! LOL!

 

[number two]

It looks so nice,I would have bought it just to show it off!

 

[bird dogger]

It looks so nice,I would have bought it just to show it off!

Agreed!! But in the end, it was the right thing to do.....even though it hurt. LOL

 

[Leonwillis]

I helped my neighbor out this summer when her deceased husband’s 1986 L2550 lost the drive clutch I was extremely close to my neighbors the husband’s was Jim he was a my best friend great guy he was a volunteer firefighter for 30 years anyway this poor tractor was bought by this camp called camp nuhop in 86 my friend Jim worked their so he ran it since new so when the camp wanted to sell it he bought because his 2 daughters were in 4H with horses so he used it constantly to move hay, manure, and in the winter to plow the drive way also when ever a storm would come through he would use it to clean up his property and his neighbors property so this poor old girl was properly sacked out it as 12,000+ hours on it but yet it starts no questions asked every time even in winter and does everything they ask of it these old kubota are some of the best old tractors and I have noticed from being on Facebook Kubota forum (trying to find a smoking deal) that it always seems to be the L2550’s that have a back story of being so worked hard but yet loved so much it really shows how much a little piece of orange iron can have such a impact on people