Hello, I am a noob. I've owned a d21-6 for the last 3 years but have not even push 9 feet of dirt,and it has sat in my garage since. I did have a mechanic come over at the time and change all fluids and readjusted the clutch. Today, I had to charge the batteries up so I could start it, and it fired right up. Problem: Whenever I release the clutch, engines dies. It did not matter if the RPM high or low. What is the prognostic? Is the clutch or transmission locked up? It ran fine last 3 years when I just started it up and moving around my garage but not more than 20 minutes. Please help.
sounds like a fuel problem. Try bleeding the system and try again
Most likely stuck brakes, a very common problem with these little critters when they sit. If it is a D21, and not a D20, it doesn't have a clutch. The peddle on the left is actually an inching pedal. Is the speed and direction shifter a U-pattern beside the throttle at your left hand? If so, it is a D21, the D20 has a manual gear shift in the floor. If you pull both steering levers back halfway, does the engine still die when you put it in gear? If you are lucky you may be lucky and get the brakes to break free, if not you will have to replace them. It is common for the steering clutches to rust together also. If you look on the first page or two of the "Dozer" forum, there is a huge thread entitled "section for D21 and similar dozers", it has a huge amount of information about this dozer and it's steering problems.
Absolute worst thing you can do to a D20 or D21 is let them rest for too long. The dry housing for steering clutches and brakes don't like that on those machines. As Mitch stated, brakes and clutches stick, sometimes only way to fix it is take it apart.
Wow, thank you all for your lighting fast help especially Mitch. It is d21a. I did pull both levers back and engines still died on me. So if I understand correctly, my little dozer does not have a clutch? When it was running, it jerked quite a bit when put in gear and the mechanic told me that he did adjust the clutch? Or he didn't? but it didn't improve the hard jerk when put in gear. Should I try different mechanic? There are extremely hard to find tractor or farm machinery mechanic around here. Lastly, how hard is it to change the brake? Can auto mechanic work on it?
It's been years since I've worked on one of those, don't remember what all is involved. I do recall you have to remove that rear panel behind the seat, remove the seat, and remove the batteries and battery tray. Don't recall what all has to be disconnected and removed to remove covers on top of steering clutches, or what it takes to get the clutches out. Sorry. :beatsme Here's the thread that Mitch mentioned, a lot of reading there. > HeavyEquipmentForums
If the engine died with both handles pulled back, congratulations, your steering clutches are stuck, too. If you had only 1 or 2 things stuck, instead of all 4, you might break it loose by running it, but I'm afraid disassembly is your only option. You could try putting in in and out of gear a few times with the handles pulled halfway back, but I doubt it'll work. Any mechanically adept person should be able to fix this. Give Darin Ray a call, he can sell you the parts and give you clear instructions, he works on these things much more often than Willie or I do. His website is www.dmmsales.com He is also a member her, and has a lot of good info in that thread. Willie is right, though, you can fix this through the top, under the seat. These dozers are very odd, having a power shift transmission, but no torque converter. The input shaft of the transmission is directly coupled to the flywheel. The hard jerk when it goes into gear is normal. I was just thinking, if that fellow thinks he adjusted the clutch, which it doesn't have, I wonder what he did do? Did you see what he did? It's a long shot, but if he tightened down the brake bands....
Thank you Willie and Mitch for the good information. There is a mechanic was told to be a specialized in Komatsu dozer will come by Monday to see what going on. This time I will watch him like a hawk and hopefully he won't tell me that he just replaced the clutch. I am a decent "fixing all" guy but come to heavy equipment I am scared. I had a leaked radiator problem with my Kubota forlklift few years back and have a mechanic come out to replace the radiator. It took him just a bit over 2hrs and later when they invoiced me, I almost fainted with ~3,900 bill. The radiator can be bought locally for 850 but they charged me 2,100, and 50 dollars for the coolant. Ever since, I'd learned from forums like this and serviced all my forklifts and find out they are actually easier to work than my cars. Hopefully, with your help and other "experts" here can turn into me a happy dozer owner.
Work on cars! Ewwww...I'd rather pour diesel fuel on them and set them on fire! Once you do get it sorted out, it's important to run those steer clutches and not let it sit for extended periods. Once a month or so, start engine, pull both steer levers back, apply brakes, and put it in fwd drive. Slowly engaged left and right steer levers one at a time to "burn in" the clutch disks and plates to clean them off. Then drive the machine while applying brakes one side at a time to burn them in as well.
Ok Willie, I believe you, you have been away from the baby Kommies a while, haven't you? Steering lever halfway back releases that sides steering clutch, all the way back applies the brake. Right pedal applies both brakes, left pedal is inching pedal, slows drive without slowing engine. I had to replace the alternator on my wife's Nissan Maxima the other day, I seriously considered leaving it in neutral with no chains so it would fall off my truck on the way to the shop, just because I hate working on cars. Willie 's right about the rest of it though, every time this subject comes up on here, I get nervous until I go run my D21. Be sure to tell the guy coming what the guy did when he "adjusted the clutch", because if he tightened the brake bands, or if you could loosen them, you might be able to break the clutches free by running it. These little crawlers are about as simple as mechanic work gets. Gpod luck, and holler if you need help. Me and Willie fight amongst ourselves, but we don't mind teaming up to help people, Mitch
Exactly Willie, I do not care work on any newer model car, given they are very reliable now a day. There is no room to work on and there are jungle and jungle of wires. Now back to my dozer, IT IS WORKING AGAIN. Follow Willie and Mitch guidance, I'd gave it some "gas" and played with inching pedal with both levers pull back, and finally it broke free. Runs like a champ besides hard jerk when put in gear. Thank you for everyone helps. I truly appreciated. Is there a way to adjust the inching thingy to smooth out the hard jerk? BTW, the brake pedal does not work very well, I had to basically standing on the pedal to stop the dozer
You probably need to run it a while to get the rust off the brake bands, then adjust them. I'm glad to hear you got it moving. On the subject of getting the jerk out of the inching pedal, I'm trying to work that one out myself. According to Komatsu, you are not supposed to use the inching pedal for shifting, just move the shifter. The transmission has a hydraulic modulating valve that keeps the pressure from coming on too suddenly. It does jerk, though.
LoL, I did say that. :tong Quick, Now, go buy a lottery ticket...you got your luck going today! :drinkup
Please read carefully! The D21 has an oil strainer just like the D20 only it is on the transmission not the bell housing. If the steering clutches are NOT releasing check this first! Check the hydraulic pressure at relief valve before condemning steering clutches. Pipe plugs providing access to various areas of the steering hydraulic system are 1/8-28 BSPT (British Standard Pipe Thread). You will need an 8mm or 5/16 12 point socket to loosen the plugs. (I was able to put together a useable pressure tester for under 60 dollars using fittings from a well-known industrial supply house. It consisted of a 1/8 MBSPT to a 1/8FNPT adaptor, then a 1/8MNPT to a 1/4FNPT adaptor, then a 24 inch (would have been better getting a 48 inch hose) section of ¼” hydraulic hose with 1/4MNPT on both ends, then to a double 1/4FNPT coupling then to a 13 dollar pressure gage good to 600 psi. Test the pressure out put of your steering pump on the transmission. It should be around 225 PSI. If not, your oil strainer is likely clogged up and needs cleaning. Since the clutches are hydraulic actuated not mechanical, if you have no oil pressure the clutches will not release. After cleaning the strainer, refill the transmission with oil and recheck. Check oil again after running for a few minutes and top off if required. Access to the strainer is best done from underneath. Back the machine up onto some blocks if it will move on its own. This gives you room to crawl underneath. Remove the belly pan with a 22mm socket on an impact wrench. I believe the bolt head size on the strainer bolts, is 13mm. Best to catch oil in drip pan. It will likely be full of grit from the dozer shedding in it. According to the manual, the oil pump on the transmission provides steering oil pressure and then provides pressure lubrication for the transmission. Diagram in manual is on 21-57 for D21-6
Did you read carefully? The clutches were stuck and it is working well now that they have broken loose.
Mitch504, Perhaps my reading skills are defective. Thank you for pointing out that the clutches are now unstuck. On the other hand since this is the Baby Komatsu dozer forum, I thought it appropriate to emphasize the importance not only from a time standpoint but a monetary one to do the hydraulic pressure check prior to starting to tear into the steering clutches, inching valve or the modulating valve or tranny. The D20 and D21 both use hydraulic pressure to move the steering clutch release arms. The D20 steering circuit operating pressure is 15 Kg/cm2 which is 214 psi. The manual lists two different steering operating pressures for the D21, depending on whether you have the A,P,S,Q-6 and P-6A or the E-6, P-6B and S-6A. The first ones spec at 27 Kg/cm2 which is 384 psi and the second ones spec at 20 Kg/cm2 which is 284 psi. Plugged oil strainers can reduce hydraulic pressure below operating parameters. If there is no hydraulic pressure for steering you can pull all day on the steering levers and it will act like you have frozen clutches. The manual mentions in the modulating valve discussion on page 21-46 that the valve “allows the machine to start without any shock, thereby improving the durability of the power train and at the same time providing a comfortable ride for the operator”. Perhaps the issues you mentioned earlier have to do with valves sticking or orifices being partially plugged. I hope all your adventures in fixing these things turn out less complicated than mine have. I have gotten some better about trying to read the manual and understand the advice they give. These things are complicated puzzles with very expensive replacement parts and doing a hydraulic pressure check early on is a great way to narrow down some issues quickly.
Oldhousehugger, your advice is well appreciated! I've run a John Deere IC440 since my Dad bought it new in 1960. I still have it and use it regularly. Now, I have a 1995 D21a-7 to play with. It is well maintained, new sprockets, new chains and runs like a champ. However, it doesn't steer! I am in the process of dissembling to inspect the steering clutches and brakes. I will also rig a hydraulic gauge to test the pressures as per your advice. The inching pedal jerks as well as the direction shifter. Service manual is on the way and every little bit of info helps. Thanks again! Don Shillinjg
Glad I could help somebody. Seems like I made almost every mistake possible when fixing my D20. I dont remember what I have written about that repair, but what I do remember is this. The steering clutches are hydraulic assist. If you don't have adequate hydraulic pressure to release the clutches they dont release. If your steering clutches are worn out, they will slip under load. If the brake bands are worn out they may not work at all or they may grab. If either of the brake release linkages are worn out they will not actuate the brakes. The needle bearing in my right brake linkage was shot and it just wobbled instead of releasing the brake. The D20 has the hydraulic pump in the bell houseing of the wet clutch. My wet clutch got water in it and stuck. When I was able to break it loose, chunks of cork clutch material got sucked into the pump intake screen and plugged it. That meant no clutch lubrication or hydraulic assist for the steering clutch release. I just put another 40 hours on it just last week busting up this concrete hard black clay where Im doing some improvements on the drainage system for my land. Im in the floodplain of the Brazos river so its either flood or drought I have to deal with to grow anything.