Suburban Plowboy
Veteran Member
I've been having an interesting day with my Chinese Alibaba-grade excavator, an AGT QK16R.
The last time I used it, I saw a long trail of oil behind it, and I realized this was not right, even for a Chinese machine. I parked it and fiddled with it. I thought the oil was coming from the slew motor.
Slew motor leaks are common with these machines because a lot of Chinese workers don't believe in using wrenches. My motor is held in by 4 M8 cap bolts with lock washers. A lot of people find that these bolts are loose from the factory. This makes the motors wobble around.
There are also 4 bolts on the underside of the motor itself, and they have been known to leave the factory loose. My understanding is that when these bolts are loose, the O-ring in the motor gets torn up and causes a leak.
I found out the size of the O-ring: 138. Don't take my word for it, because I haven't installed one yet. I got some O-rings.
Today I got into the excavator. It is an amazing piece of machinery. I don't mean that in a good way.
To get to the slew motor, you have to take off the floor plate. Easy, right?
I removed every bolt that held the floor on, and of course, all sorts of stuff was still in the way. The pedestal with the controls, mainly.
I learned some things that may help others.
1. Do not try to take off the lower sheet metal. AGT puts welded nuts on the upper sheet metal, where you don't really need them, and it uses loose nylocks for the lower sheet metal. They are very, very hard to get at for loosening and tightening. Welding nuts to the inside of the excavator would be a good mod.
2. Removing the upper sheet metal is not hard, but it is tedious. You have to take out 8 screws and nuts, plus two bolts, to remove the door in front of the engine. The 8 screws are in hinges which don't work because AGT made it impossible for the door to swing. A clever guy tapped the pins out of his hinges and replaced them with R-clips. I plan to do that, although Velcro would probably work just as well.
3. You should remove the foot pedal in order to get the floor off. It is held on by one oddly-chosen screw with a nylock.
4. You will have to remove the lower canopy support which is bolted to the frame. The bolts that hold it on go through the floor for no good reason. I am going to turn the holes into slots so I can loosen the bolts and lift the floor up instead of removing the support. The support is not needed to hold the canopy up, because the canopy bars in the rear are mounted solidly to the excavator frame.
5. One guy recommends cutting off the bit of the floor to the right of the control pedestal. It doesn't really need to be connected to the rest of the floor. It can be reinstalled after cutting it. Some minor mods could be added to make everything stiffer.
6. Another guy recommends cutting the floor in two big pieces, front and rear.
7. When you get the engine door off, you get access to the front oil dipstick. This machine has two dipstick holes, front and rear, and AGT puts the dipstick in the front one where you have to take the excavator apart to get at it. The holes are interchangeable, so while the door is off, swap the plug at the rear of the engine for the dipstick in front. Now you can check your oil.
It turned out my slew motor was just fine, sort of. The bolts were not very tight, but the motor was not loose. I pulled the bolts out, applied Loctite, and reinstalled them. I don't know the actual torque figure, so I went with a Chinese measure: yu wei tai nau.
I am going to pull it again and check the bolts on the underside. I don't want to put the excavator together and then have the motor fail.
The hydraulic fluid was coming from a valve thing (hydraulic swivel joint?) that feeds the track motors. When I looked at it, without even checking, I thought it looked weird. One one side, there were three screw-on fittings, and one was clearly farther from the motor than the others, suggesting it wasn't tightened all the way. I fired the machine up, moved the tracks, and saw oil dripping out of the fitting.
Now I have to tighten that fitting. I wondered how I would do it, because access is nearly nonexistent. It's under another fitting which I can reach, but I can't get to the leaky fitting itself. I realized I could remove the top fitting, tighten the leaky one, and reinstall the top one, so that's what I'll do.
I checked whatever I could reach to make sure nothing else would come undone, but I can't get at everything without a ton of work, so I plan to put the excavator together and hope for the best. I'm glad nothing was damaged.
The moral here is to tighten everything you can on your Chinese excavator. Also, change the hydraulic fluid before you run it, and don't be afraid to modify it. You really are smarter than the engineers who designed it.
This info ought to be very helpful to people with the exact same excavator, and it should be somewhat helpful to people with similar models.
The last time I used it, I saw a long trail of oil behind it, and I realized this was not right, even for a Chinese machine. I parked it and fiddled with it. I thought the oil was coming from the slew motor.
Slew motor leaks are common with these machines because a lot of Chinese workers don't believe in using wrenches. My motor is held in by 4 M8 cap bolts with lock washers. A lot of people find that these bolts are loose from the factory. This makes the motors wobble around.
There are also 4 bolts on the underside of the motor itself, and they have been known to leave the factory loose. My understanding is that when these bolts are loose, the O-ring in the motor gets torn up and causes a leak.
I found out the size of the O-ring: 138. Don't take my word for it, because I haven't installed one yet. I got some O-rings.
Today I got into the excavator. It is an amazing piece of machinery. I don't mean that in a good way.
To get to the slew motor, you have to take off the floor plate. Easy, right?
I removed every bolt that held the floor on, and of course, all sorts of stuff was still in the way. The pedestal with the controls, mainly.
I learned some things that may help others.
1. Do not try to take off the lower sheet metal. AGT puts welded nuts on the upper sheet metal, where you don't really need them, and it uses loose nylocks for the lower sheet metal. They are very, very hard to get at for loosening and tightening. Welding nuts to the inside of the excavator would be a good mod.
2. Removing the upper sheet metal is not hard, but it is tedious. You have to take out 8 screws and nuts, plus two bolts, to remove the door in front of the engine. The 8 screws are in hinges which don't work because AGT made it impossible for the door to swing. A clever guy tapped the pins out of his hinges and replaced them with R-clips. I plan to do that, although Velcro would probably work just as well.
3. You should remove the foot pedal in order to get the floor off. It is held on by one oddly-chosen screw with a nylock.
4. You will have to remove the lower canopy support which is bolted to the frame. The bolts that hold it on go through the floor for no good reason. I am going to turn the holes into slots so I can loosen the bolts and lift the floor up instead of removing the support. The support is not needed to hold the canopy up, because the canopy bars in the rear are mounted solidly to the excavator frame.
5. One guy recommends cutting off the bit of the floor to the right of the control pedestal. It doesn't really need to be connected to the rest of the floor. It can be reinstalled after cutting it. Some minor mods could be added to make everything stiffer.
6. Another guy recommends cutting the floor in two big pieces, front and rear.
7. When you get the engine door off, you get access to the front oil dipstick. This machine has two dipstick holes, front and rear, and AGT puts the dipstick in the front one where you have to take the excavator apart to get at it. The holes are interchangeable, so while the door is off, swap the plug at the rear of the engine for the dipstick in front. Now you can check your oil.
It turned out my slew motor was just fine, sort of. The bolts were not very tight, but the motor was not loose. I pulled the bolts out, applied Loctite, and reinstalled them. I don't know the actual torque figure, so I went with a Chinese measure: yu wei tai nau.
I am going to pull it again and check the bolts on the underside. I don't want to put the excavator together and then have the motor fail.
The hydraulic fluid was coming from a valve thing (hydraulic swivel joint?) that feeds the track motors. When I looked at it, without even checking, I thought it looked weird. One one side, there were three screw-on fittings, and one was clearly farther from the motor than the others, suggesting it wasn't tightened all the way. I fired the machine up, moved the tracks, and saw oil dripping out of the fitting.
Now I have to tighten that fitting. I wondered how I would do it, because access is nearly nonexistent. It's under another fitting which I can reach, but I can't get to the leaky fitting itself. I realized I could remove the top fitting, tighten the leaky one, and reinstall the top one, so that's what I'll do.
I checked whatever I could reach to make sure nothing else would come undone, but I can't get at everything without a ton of work, so I plan to put the excavator together and hope for the best. I'm glad nothing was damaged.
The moral here is to tighten everything you can on your Chinese excavator. Also, change the hydraulic fluid before you run it, and don't be afraid to modify it. You really are smarter than the engineers who designed it.
This info ought to be very helpful to people with the exact same excavator, and it should be somewhat helpful to people with similar models.
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