Importing and modifying a new mini excavator from China

[dfkrug]

Only a 10hp? The unit must be pretty small. I would be thinking a Kubota or Yanmar
in the 23hp range.

This mini-X is Really Small, just like the Kubota K008. There are dozens of makers of excavators,
and thousands have been made big-and-small, especially after the mid-90s. It is surprising to me
that EPA rules for tiny diesels (SORE) have made it so restrictive that makers are abandoning them.
It also seems that 700+cc in a Yanmar or Kubota 3-cyl should put out more than 10hp. The bigger-
is-better crowd is not going to like this machine. But the owner that needs to squeeze into a tight
backyard or inside a building will see the advantages. Hauling one is also possible in the bed of a
large PU.

But back to my XN08. Since I received my unit partially disassembled for shipment, I did not fully assemble it
until I finished all my mods and testing. Complete pix and 5 videos on my Utube page will be linked at the
end of this thread.

My seller provided accessories and spares at what seems like their cost. In the pix I show a larger bucket, a
ripper tooth, a mechanically-linked grapple, spare filters, and even a toolkit and box. The toolkit contains a complete
set of open-end wrenches 8-30mm and even a grease gun with needle tip. You can see the main spool valve
spare that I traded for my missing engine. It actually costs a bit more than the ChangChai engine. I got 2 spare
bucket cyls at only $50 each, for example. The standard bucket comes with bolt-on teeth. A mechanical thumb is
standard, tho I will use the AUX valve to power a hyd thumb that I plan to make later.

Some nice features of this machine are the steel canopy with integrated rollbar. The main body sheet metal is
2mm (.075") and is quite substantial. The joystick rods and finish screws are stainless steel. All cylinders seem
to have replaceable sleeve bearing inserts. Some of the pins have threaded ends with nylock nuts.

 

[majorwager]

Are the you tube videos available now?

 

[dfkrug]

I went with a Chinese Honda-clone single cyl gas engine with electric start. Some call
these Chondas, tho makers in China have taken the Honda GX390 design up to 420 and 440cc.
Some of the genuine Honda engines are now made in China.

Like the mini-X, there are many factories in China making this engine. Mine is made by
Chongqing Dajang Power Equipment Co and imported by a company in SoCal, which calls it
Duramax. It is identical in all the ways I can see, other than paint, to the HarborFright
Predator 420. Note that HF has a hemi version of this OHV engine for the same price with
a bit more low-end torque. The Duramax 16hp cost me $330 delivered, incl tax, about $50 less
than HF. That's about 1/3 the price of a Honda GX390. Duramax has a 440cc engine, but
it runs $500....maybe that one has pressure-lube?

I have had and repaired a number of these Chonda engines, and was usually disappointed
in how well they are made. That is improving, however. Sediment in the bottom of the
fuel tank and worn out pull-starters are weak points. Mine arrived missing the shaft
key, but one was sent to me right away.

 

[dfkrug]

Are the you tube videos available now?

Anyone who wants to jump ahead can go to my Utube page:


walkaround after most mods installed:
XN8 walkaround Small - YouTube

startup testing:
XN8 initial startup - YouTube

pressure test:
XN8 mini-excavator pressure test - YouTube

testing the log grapple:
XN8 log grapple on mini-X - YouTube

first digging test using larger bucket with new welded-on teeth:
XN8 digging - YouTube

More explanations will be forthcoming.

 

[TractorGuy]

I went with a Chinese Honda-clone single cyl gas engine with electric start. Some call
these Chondas, tho makers in China have taken the Honda GX390 design up to 420 and 440cc.
Some of the genuine Honda engines are now made in China.

Like the mini-X, there are many factories in China making this engine. Mine is made by
Chongqing Dajang Power Equipment Co and imported by a company in SoCal, which calls it
Duramax. It is identical in all the ways I can see, other than paint, to the HarborFright
Predator 420. Note that HF has a hemi version of this OHV engine for the same price with
a bit more low-end torque. The Duramax 16hp cost me $330 delivered, incl tax, about $50 less
than HF. That's about 1/3 the price of a Honda GX390. Duramax has a 440cc engine, but
it runs $500....maybe that one has pressure-lube?

I have had and repaired a number of these Chonda engines, and was usually disappointed
in how well they are made. That is improving, however. Sediment in the bottom of the
fuel tank and worn out pull-starters are weak points. Mine arrived missing the shaft
key, but one was sent to me right away.

I bought one of the DuroMax generators off ebay last year. It came with the 18HP dual fuel engine. My daughter has it and has not used it yet so I have my fingers crossed it will work. I test ran it on both propane and gas under a load and it would run continuous at 8KW with either. Applied the max 10KW it was rated for and it fell on it's face.

 

[dfkrug]

I bought one of the DuroMax generators off ebay last year. It came with the 18HP dual fuel engine. My daughter has it and has not used it yet so I have my fingers crossed it will work. I test ran it on both propane and gas under a load and it would run continuous at 8KW with either. Applied the max 10KW it was rated for and it fell on it's face.

That is the 440cc engine, about the biggest thumper you can get for small equipment. Does it have
an oil pump for lubrication? I recently killed my Chinese Generac inverter genny when I tried to start my
reefer. Not repairable. :-(

 

[dfkrug]

These are the modifications that I did to get my machine going:

Modifications:
-- ChangChai diesel engine replaced with CARB/EPA-certified 420cc DuroMax 16hp gasoline engine
-- hydraulic pump relocated from right side to left
-- engine cooling fan duct moved to right side from left
-- diesel fuel tank removed
-- spin-on hydraulic fluid filter added on return line to tank
-- needle grease fittings replaced with zerks
-- small electric fan added to left side of house
-- hydraulic oil temperature gauge installed
-- carburetor air inlet ducted to outside of house
-- electrical wiring redone to add engine OFF function
-- controls changed from excavator-style to backhoe-style

The photos show the diesel engine installed in another unit. Note the rubber air
duct that routes the cooling fan air in from the outside of the house. The duct
replaces the pull-start assembly. You can also see a hydraulic oil cooler, which
my unit does not have. I wish it did, and I may add one later.

 

[majorwager]

Purchased my hydraulic oil cooler from a firm in California.

 

[dfkrug]

Purchased my hydraulic oil cooler from a firm in California.

Did you also use the fan? I will bet that one takes several amps to run.

The DuroMax 420cc engine has an alternator to charge the battery, but little else. It puts out about
650mA at mid-speed, and about 700mA at higher RPM. The LED worklight takes 600mA. The small
120mm electric fan I installed uses 350mA. Actual measurements with an ammeter.

 

[dfkrug]

In prepping for my new engine, I removed the diesel fuel tank. It features a spin-on
filtration system and very nice sight glass to monitor fuel level. The walls of the tank
seem to be 4mm steel. The fill tube is also steel. There is even a brass petcock to
turn off this gravity-fed system. Nicely made. Too bad it has to go, due to space
constraints.

 

[dfkrug]

The hydraulic oil tank also features a very convenient sight glass just like the one
for the fuel tank. It is also a hefty 4mm-wall steel tank. The machine welds
look great.

The first photo here shows the tank and pump on the right side of the house
chassis, as it originally was made. The system features a steel mesh suction
filtration system, but no return-to-tank pressure filtration system. That was my
first major upgrade. Suction filtration is not a good solution to oil contamination
problems on any hydraulic equipment. The inlet screen looks like a 100-micron screen
without any bypass valve to avoid cavitation.

The filter chamber has a very nice large opening, sealed with an O-ring. This
allows inspection and cleaning of the tank. The suction filter is large, and even
comes with a Neodymium magnet attached.

I had to siphon out the hyd fluid before removing the tank since the drain plug
needs to be removed for clearance. Draining the oil thru the drain plug is not
easy unless the house is rotated to clear the tracks.

I bought a return filtration system from our friends at SurplusCenter, along with
a spare filter. Their Zinga 25GPM system features 10-micron filtration with a bypass
valve and 3/4" NPT threads. Only a bit over $30 for the manifold and 2 filters.

I chopped up a 3/4" steel pipe nipple to make the new bung hole in the tank.

Tho there was clearance to install the filter in a downward configuration, hidden
under the floorboard, I opted to install it so that it penetrated the floor for
easy replacement. This was an easy upgrade, and I am encouraging the factory
to make this change. I suspect that with 100u suction-only filtration, the life
of the pump will be limited to a few hundred hours.

 

[ArlyA]

We've got items from the Surplus center as well and do like that shop. You can email them a qestion and get rear answers. Your mini excavator from China, looks better built than I had expected. I found them for about $4000 (no shipping from China) and I believe that was with a 11hp motor. Thanks for posting the photos and videos, especially of it at work.

 

[dfkrug]

Your mini excavator from China, looks better built than I had expected. I found them for about
$4000 (no shipping from China) and I believe that was with a 11hp motor.

I am trying to point out the good things I have discovered, as well as improvements that are necessary, IMO.

If you delete all the options and shipping, you can get this unit FOB in the low $4000s range as you found.

As for the return-oil filtration kit, I bought my first kit from SurplsCntr back in the 90s for my CADDigger. For
the Chinese minis, I suspect that the next size up has this feature already. One factory has verified this for their 1.6T
and bigger units. I sure wish all the makers provided more technical details.

Here is another good quality feature of my XN08: Look at the massive frame-mounted contactor (starter solenoid)
in my first photo of my last post. I used that instead of the engine-mounted small contactor that came with
my new engine.

 

[dfkrug]

In test fitting my new engine, I could see that it was a different shape than the diesel
it replaces. It was not going to fit between the frame rails with the output shaft pointed
right, where the hydraulic pump was originally located. So I had to position the engine
where the pump would be on the left side instead.

The maker provided 1/2" thick mounting plates with large holes to support 8 rubber
isolator mounts. Nice. I welded on 2 transverse brackets to attach to the engine base.
I cut out a small chunk of one frame rail to avoid interference with the pump inlet
fitting and hose. I wanted to mount the engine and pump as low as possible to avoid
any chance of sucking air from the tank.

BTW, the pump is some Chinese brand that I have never heard of, but it is all-steel, not
like the aluminum ones I have purchased most recently.

 

[dfkrug]

Next comes the engine coupler I had to make.

The maker provided a spline adapter for the pump for a direct-coupling. I was hoping to
use something like a Lovejoy coupler (photo), but clearance was tight, and it
would not fit inside the provided pump-to-engine mount. That mount lined up perfectly
with the bolt holes on my engine.

So, I decided to weld up a direct coupling. First, I chopped nearly 2" off the crankshaft,
and used that to help align the 1" keyed coupler I needed. Instead of buying 1" keyed
coupler stock, I bought a sprocket with a wide 1" keyed bore. Sprockets are usually cheaper
than coupling stock, and they have a wider boss for easier welding.

I put the female splined adapter on the lathe and made an alignment cut to help with
welding the two halves together straight. The 1" stub from the crankshaft was used inside
the sprocket hub to make sure both parts were concentric. I then welded and cut off the sprocket.

The paint job is always last, but usually necessary.

Even with a direct pump coupling, I needed to make a spacer to create some extra clearance on
the pump-to-engine mount. So I cut a 3/8" ring out of some scrap steel plate. The final photo shows
the completed left side pump installation.

 

[dfkrug]

All the hydraulics on this machine are metric sizes, and proved one of the bigger
challenges of this project. I got the adapters I needed from our friends at Discount
Hydraulic Hose in PA, but they were spendy, and one I could not find at all. I had
to make the adapter for the small hose that provided flow from the AUX circuit on the
dipper.

Standard-length new SAE hoses worked fine for me, so I did not have to have any
custom hoses made. The cost of adapters was higher than the whole filtration system.

 

[radios1]

seriously, this is more of a make work project/hobby type deal, which can be fun for that aspect, but requires a lot of work that most people don't have the machines for.. so for them, it would cost much more to have this done, than just buy an excavator that is fully assembled, and working..

 

[majorwager]

radios,

I disagree. The excavator would have been functional W/ deletion of the many modifications elected by the OP. True he chose to present the appearance of a hobby project, simply because he has the time, ability, and desire to perform the mods. I have not studied the engine to pump connection, but there may have been a simpler, less precise but More $$ solution. The OP may have desired to build his own excavator, but the tractive drive system and boom construction were too intensive. If my goal was to just get the machine functional, it would already have most of the trail work complete.

The OP has a sense of perfection and pride so this project BECAME A JOINT VENTURE between construction and equipment build/mods. Filtration was optional. Had it been his desire, an EPA approved diesel engine might be available to mate to the existing hydraulic drive. Another point missed, is the OP desire to employ his adaptive abilities to short circuit unnecessary cost overruns. Based upon his initial investment, the budget likely supported more elaborate accessory ready made purchases, but where is the fun in that? Showing how ones ingenuity defeated the money grinch, is the stuff that can occupy a whole cocktail hour or campfire outing, and them some.

Which is preferable? a buddy stops over, says nice machine, did you buy it all put together? Answer A, yea kinda, just bought a bunch of pre-engineered stuff and bolted it on. Answer B, well actually I hand fabricated all these components, machined that, adapted that, extended this, ARE You getting the big PICTURE?

NONE of this diminishes the painstaking effort to purchase and import a piece of equipment from china as an INDIVIDUAL.

 

[dfkrug]

seriously, this is more of a make work project/hobby type deal, which can be fun for that aspect, but requires a lot of work that most people don't have the machines for.. so for them, it would cost much more to have this done, than just buy an excavator that is fully assembled, and working..

Indeed it WOULD cost more to have this work done, versus buying a ready-made machine. IF you could buy
one. Our pals in Canada or Australia can certainly buy it ready-made. As I mentioned above, the closest
I was able to get to a ready-made unit was at about $10K for a used high-hour machine from a dealer
out of state.

I am offering up my design work and modifications currently to 2 Chinese factories (gratis) who have expressed
interest in making these changes so they can sell more units into the US. I will help them, plus I have
at least one person in mind as an importer here in CA who would retail and repair these units.

 

[dfkrug]

Let me share a similar solution to the problem of importing one of these units without an
engine.

Charlie in OR brought one in before I did and he ran into the same EPA buzzsaw. He bought
a Predator 420 from an ubiquitous HarborFreight store, and installed it without doing anything
to the hydraulics at all. The engine was shoe-horned in at an angle so the pump could
remain where it was originally. A LoveJoy coupler was used, which is longer and costs more
than what I did. He had to make a different pump mount so it would clear.

The upshot of his approach is that the engine sticks out the back, so the rear bodywork can not
be reinstalled. He was able to get up and running fairly quickly however. Cooling issues also
made it so he could not enclose the engine. I elected a different approach, but I understand
why Charlie went this way.

There are 2 others in the US I have spoken with who have substituted gas engines for the
original diesel: one in Utah, and one is NE. Since they have not sent me pix or provided
details, I don't have much to share on those mods.