Restoring a Kubota B20 Tractor – Part 6

Spring is knocking at the door, and I am not ready! I have several projects already lined up that I want to use this tractor for, so I need to get it finished up! That said, I still want to paint it since it is disassembled and it is a new skill I want to learn.

I separated all the orange bits from the blue bits, so I could cut down on much of the masking and do a better job at the transitions. I had to figure out a way to lift the loader off without being able to use its own hydraulics (which is how they always seem to be removed on YouTube). I put it in a sling with a ratchet strap and lifted with my engine hoist. I put the rear tires back on the tractor, a rolling hydraulic jack under the front, and rolled the chassis out from under it.

Sidenote – I am not sure why I always end up doing these things in the least efficient order! If I had just removed the loader in the very beginning 1) the tractor would still had both axles and rolled out from under it much easier and 2) removing the front axle / engine would have been so much smoother not working around the loader arms.

Then I welded up some scrap steel to support it using the wedge bolt pin holes. I had to add a strap to keep my support pins from wanting to walk out when working on it, and another to keep the main arm cylinder from wanting to expand & tipping my support stands over.

These machines have a lot going on under those fenders!

Now I am sanding out as many of the blemishes as I can. I have some new decals on order, and hopefully will soon be laying down some nice shiny new paint.

It’s been several weeks since the last update, and I really was hoping the next update would be a running engine. Unfortunately I had a setback on that, which I will get into shortly. This one is going to be a double update!

First up is that the engine and chassis painted up very nicely. I painted the engine and each of the disassembled chassis sections separately, and then again after having them re-assembled. This allowed me to get better coverage on each section, and then the additional coats after assembly took care of the scratches from re-assembly that are bound to happen.

Painted Kubota D950 Diesel Engine
Painted Kubota B20 Chassis
Painted Kubota B20 Chassis

The cherry picker / hydraulic shop crane has proven invaluable for this project. Besides the normal engine pulling / installation, I have been able to use heavy ratchet straps to sling larger assembly’s like the entire front end loader and the front axle / chassis sub-frame. With careful control of each ratchet strap, I was able to pitch the assembly just how I needed and then line up the frame bolt holes for assembly completely by myself. Even with the aid of several big guys, I do not think that could have been done very easily without it!

Assembling Kubota Chassis with Shop Crane

Once the engine and chassis were all bolted back up, I wanted to test fire the engine before assembling it any further.

Kubota B20 prepping for engine test

I hooked up the minimum connections needed in order to get fuel to the injection pump, and power to the glow plugs and starter. I did not have the radiator installed yet, so I would only be able to run the engine briefly. I also had a scrap piece of wood handy to suffocate the intake with, just in case I did not get all the governor springs inside the injection pump reinstalled correctly.

I bled the air out of each of the injection lines, energized the glow plugs, and cranked it over. Sadly it wouldn’t start. I gave it several attempts and re-bled the injector lines just in case they still had too much air. Eventually I gave up for that night. Later I took the injectors back out for a compression test. I was seeing compression of about 200 psi on #1 and #3, and only 90 psi for cylinder #2. I double checked the valves were adjusted correctly, as that can also give low compression, but all was good there.

I began to suspect the head was cracked from overheating. I know the engine had a history of overheating before it was taken out of service 9 years ago, and likely ran without coolant on at least one occasion due to the cracked T-stat housing I found.

When I had it apart, the cylinder head was warped (about 8 thousands out). I was able to re-surface it myself following YouTube videos, and brought back to within 2 thousands of being flat, which is the workshop manual spec. I also lapped the valves, and was not able to visually see any cracks at that time.

It did not really make sense to have it sent into a shop to be magnafluxed, as the #2 cylinder was pretty eroded, and these heads are cheap enough that if it was cracked a new head from eBay would likely be the same cost or less than repair work on the head. Given that, and the eroded #2 head area, it would not make sense to spend a lot of money repairing this head. But since I didn’t see any cracks at the time, I was willing to invest in a head gasket to give it a shot.

Later after it was all assembled and I had painted the engine, I noticed a crack on the external surface of the head. It appeared to be only in the water jacket area, so I put epoxy on it and tried to forget it was there to ease my mind! But now that my compression is low, the most obvious answer is there were additional cracks that I had not seen.

The good news is I was able to pull the head fairly quickly, without needing to remove the entire engine again.

Kubota B20 Engine Head Removed

I stripped the old head and cleaned it back up for a second inspection. I used a brighter light and a magnifying glass this time. I did find there are at least two cracks in the combustion area, between the valve seats and web to the recessed combustion chamber. Here is a full shot of the head, and even knowing where to look in the photo, I can’t see the cracks. You can see the large pitting / erosion of the #2 cylinder though, which is why I didn’t want to invest in any machine shop work for this head.

Here is where I epoxied the external crack I had mentioned in the previous post.

D950 external head crack

This is the first internal crack I found. It runs well into the valve recess, across the hardened valve seat, along the lower corner of the valley and down into the recessed combustion chamber. This one actually shows a little better in the photo than it does in person. The camera flash must catch it well.

Kuboto D950 internal head crack

I also discovered this one as well. It crosses the valve seat, and then continues straight into the valley between the ports. It’s harder to see, but its there.

Kuboto D950 internal head crack

I have purchased some penetrating dye and developer to make finding these kinds of issues at home much easier in the future. I may test it out on this scrap head when it comes in just to see what else shows up!

In the mean time I have ordered a Kumar Bros aftermarket replacement head for this engine. The reviews I could find were mostly positive, and it is quite a bit less expensive than a genuine Kubota one. Hopefully the next update will be a running engine!

Click here for Part 7 on the Kubota B20 rebuild.

Restoring a Kubota B20 Tractor – Part 5

Lots of progress to update!

Two of the cylinders cleaned up to within spec after surface honing. Cylinder #2 had some very heavy pitting, most likely from water sitting in the cylinder. It needed to be re-sleeved.

Kubota D950 - Ok Cylinders
Kubota D950 - Bad Cylinder #2 with heavy Pitting

I took on re-sleeving the cylinder myself, and it was much more work than I anticipated. I removed the old sleeve by carefully chiseling a slit from top to bottom. I stuck the new one in the deep freezer before installing, but it still took several hours of work in combination with additional ice packs to finally drive it in. If I ever to another one of these, I am definitely going to use dry ice.

Driving in New Cylinder Sleeve

Another surprise was to learn that Kubota cylinder sleeves are not bored to final size, due to the amount of force they require for installing. I was not able to find a local machine shop that could do the work that wasn’t already backed up several months. I decided to try boring it myself using a neighbors hone that he was sure could also bore. I was skeptical, but to my surprise, with some patience and frequent bore measurements it worked great! This wasn’t the common inexpensive cylinder hones. It had gear driven racks that applied the pressure to the stones and kept them parallel. After several hours of working with it, I had a cylinder within 3 thousands from top to bottom, and side to side, which is within the factory specs.

After flushing all of the honing grit out of the crankcase really well, I changed out all the crankshaft main bearings and seals. I also polished the crankshaft journals.

Kubota D950 Crankshaft

I ordered the rebuild kit that included new pistons along with the rings. Here is a shot of the crankcase all cleaned up right before putting the oil pan back on.

Kubota D950 Crankcase with Oil Pan Removed

Next, I resurfaced the engine head and ground and polished the valve seats. One of the exhaust valves needed replacing due to stem wear.

Kubota D950 Engine Head

While putting everything back together, I think I found the cause for the original overheating problems. The T-Stat housing had a crack all the way through, in a location that was almost impossible to see when the engine was assembled. It was a pretty expensive part to replace, so I decided to braze it with Allumiweld rods, which are made for repairing aluminum.

Cracked Kubota D950 T-Stat Housing
Repaired Kubota D950 T-Stat Housing

And the final post of updates for now, I have the engine re-assembled and have painted it with primer. It will also be getting a coat of the Kubota Dark Grey Acrylic Enamel before installation.

Kubota D950 Prepped for Paint
Kubota D950 Primer 1
Kubota D950 Primer 2
Kubota D950 Primer 3

I am now working on cleaning up and painting the rest of the tractor before putting everything back together again. If anybody knows a good source for Kubota Decals, please let me know!

Click here for Part 6 on the Kubota B20 rebuild.

DIY Solar Generator – Plexiglass Cover and Improvements

In this update to our DIY Solar Generator how-to series, I am going to show you how to build an acrylic Plexiglass cover for the inside of the solar generator, so that we can store things like jumper cables inside the case without worry about shorting out or damaging any of our wiring connections. I will also show you some updates and improvements that I have made since the original videos, including a way to automatically disconnect the solar charger from the battery when the solar panels are unplugged. This will keep the solar charger from slowly running down the battery while in storage, without having to remember to turn on or off a disconnect switch. I will also show you a better solution I have found for the solar cable wire including heavier gauge cable, for less cost, and a built in cord wrap.

Continue reading DIY Solar Generator – Plexiglass Cover and Improvements

How to Drive in Snow on Hilly Roads

In the video below, I demonstrate driving a modern 2 wheel drive, front wheel drive vehicle on some hilly unplowed snowy roads. I also will show why in some circumstances traction control can limit your ability to climb or get unstuck. There are certain situations where turning traction control off can actually help.
Continue reading How to Drive in Snow on Hilly Roads

Restoring a Kubota B20 Tractor – Part 4

I repeated the compression test because I didn’t record the numbers before. In order to perform a compression test (using the injector holes), you will need to remove:

  • Air Filter Housing
  • Metal Injector Lines
  • Fuel Overflow / Bleed Line
  • Metal OverFlow / Bleed Line Rail
  • Injector Nozzles (make sure to remove the copper gasket from the bore for each one as well)

At this point you can test the compression of each cylinder. While cranking the engine, be sure to pull and hold the engine shutoff rod, so the injection pump is not squirting diesel fuel.You can optionally disconnect the glow plugs power wire to conserve battery as well.

The values I read for each cylinder was from back of engine to front (dry):
80 PSI – 160 PSI – 160 PSI

Since the #1 cylinder was especially low, I squirted some oil in the cylinder and repeated (wet).The value rose to 150 psi, which is a good indication the issue is with the piston rings, and not a valve issue.

The service manual spec for allowable range on compression is 337-448 psi, so all three cylinders are well below spec.

Kubota B20 Engine

At this point I pulled the head to check for any signs of damage to either the head, valves, or the pistons.

To remove the engine head on this tractor, you will need to (starting with parts already removed for compression test above):

  • Drain Oil & Coolant
  • Remove Air Filter Bracket & Fuel Filter Mounting Bolts
  • Remove Firewall Mounting Bracket Bolts to Head
  • Remove Exhaust Manifold (optional)
  • Disconnect Fuel Supply Hose to Injection Pump
  • Remove Air Intake Manifold
  • Remove Glow Plugs
  • Remove Top Radiator Hose
  • Remove Top Mounting Bolt on Alternator (and swing alternator out of way)
  • Move Fan Belt OfF Pulley
  • Remove Valve Cover
  • Remove Valve Rocker Arm Assembly
  • Remove Push Rods (inspect to make sure they are all straight)
  • Remove Head Bolts
  • Lift Head Assembly from Engine

The engine is quite crusty with carbon deposits, but I don’t seen any signs of head, piston, or valve damage yet. I will post a follow up again once I have pulled the valves apart and cleaned everything up for a more thorough inspection.

Kubota B20 Valve Cover and Rocker Arms Removed
Kubota B20 Engine Head Removed
Kubota B20 Underside of Engine Head

Click here for Part 5 on the Kubota B20 rebuild.

How to Control a Slide on Icy Surfaces

This video of a pile up in Montreal has been making the rounds in social media. It shows multiple vehicles, including two buses, a police car, and even a plow truck piling up on a very slippery roadway. It also perfectly illustrates both what works, and what not to do. The majority of the vehicles, including the plow truck, did not know what to do. Do you?

Continue reading How to Control a Slide on Icy Surfaces

How To Build a Large Solar Generator – Part 4 – Wiring

This is the fourth part in our series on how to build your own large solar generator. In this part we will be completing the wiring for the generator, including the solar charge controller, AC inverter, LED work lights, and USB outlets.

Continue reading How To Build a Large Solar Generator – Part 4 – Wiring

Restoring a Kubota B20 Tractor – Part 3

Getting back into this project. We have moved since I started this project and now have a garage bay I can use to continue working on the tractor. I was never able to get it to fully fired up. It would sputter and almost catch but never quite start. I finally did a compression check and was seeing low compression on all three cylinders, with one very low. I am guessing there was some engine damage due to overheating issues it was having back when it was running last.

Since it is going to need a rebuild of some sort, we loaded it up on my trailer and brought it back to my house where I can work on it in the garage.

Loaded Kubota B20 onto trailer.

Once back at my house, I needed to figure out a way to raise the bucket and hold it there so it wouldnt guoge the concrete. Many of the hoses are leaking, so I needed an external way to hold it up. I used a floor jack to lift the bucket off the ground, and a scrap board placed into the linkage to prevent the hydraulic cylinder from collapsing back down worked very well!

Lifting and holding bucket up with no power and leaking hoses.

Safely in the garage so I can start the engine tear down.

Kubota B20 before engine tear down.

She has definitely seen some wear, and sitting outside has taken a toll too. These pics will hopefully serve as some good “before” pics once I get it back up and running and cleaned up!

Kubota B20 weathered seat.
Kubota B20 weathered engine compartment.
Kubota B20 weathered 3 point hitch

Click here for Part 4 on the Kubota B20 rebuild.

How To Build a Large Solar Generator – Part 3 – Component Mounting

This is the third part in our project series How To Build a Solar Generator. In this part, we will be mounting all of the components into our case, as well as some of the preliminary wiring.

Continue reading How To Build a Large Solar Generator – Part 3 – Component Mounting

Teardown, Overhaul, & Re-Assembly of Yazoo Mower Transmission

I snapped an axle shaft in my Yazoo Mower (YR-76) that required disassembling the entire transmission in order to get the broken shaft out. While it was out, I cleaned each part, and replaced worn bearings and oil seals. Here is the process I took.

Continue reading Teardown, Overhaul, & Re-Assembly of Yazoo Mower Transmission