Komatsu D20-PLL6 Dozer- What is trans hydr pump for ?

hillbillyWT

New User
Problem 1:
I was moving some slash on the farm. A hydraulic hose inlet on a hydraulic cylinder got ripped off. I don't know how- I just know one minute, tra-la-la moving slash, next minute hydraulic oil is pouring out of the left hand side(as you site on the machine) 6 way blade's left had side blade angle tilt(way it tilts to right or left or can straighten up).

The fitting broke off so bad I do not not think I can repair the hydraulic cylinder. Big Woof, I have a pit in my stomach because I cannot find anything remotely like the cylinder on it, and I'm tight on cash right now and do not know if I can afford a pair of cylidners, even from liquidation place.

Problem 2:
Since problem 1, the machine is acting like the clutch mechanism is stuck. In other words, I crank it, I push down on clutch, put in gear, let off on clutch pedal- clutch pedal laughs at me and stays down stuck. I can take a wrecking bar and pull up on it and the tractor the is in gear- but put the clutch pedal down to shift and it is the same story.

I have a neighbor who had one of these and he said it is the transmission pump. To try to drop the undercover and clean the filter, but more than likely I'm looking at $500 and a lot of pain.

The engine is strong enough that I can actually start the tractor in gear, and then lower rpms to where it is about to die, shift without grinding by barely depressing clutch pedal, it starts to die, then I can increase throttle and go through all the gears.

Dozer has legit fresh off the boat 1700hr hours. I paid $2000 at an estate sale as it was a pig in a poke. I knew the Mitsubishi 4 cylinder engine was good, so I figured it was worth that.

Machine was imported in Texas, some fellar moved from Galveston to East TN. He sold it. An old man down in Georgia bought it, passed away, and I went to his estate sale. Cheapest thing there, a friend roll backed it home for $80.

The steering clutches stick if you let it sit a long time, but you can pretty easy break them free if you bury the blade and then work the clutches left and right.


Problem 3: What Oil do I need to be using in the hydraulic system ? The Universal Tractor Fluid was included with the machine. The very limited notes I got on the machine indicated that it needed 40w oil in the machine. I could not find straight 40w, so I used the UTF- I looked it up and Nebraska and Missouri have delisted it. What is an acceptable fluid for this machine ?

Thank you all.
 
Can't weld the fitting back on? Or weld a new fitting on? Worst case a shop can retube it cheaper than a new cylinder
 
Do you have the manuals (operator's and service? If not you should get them, they have answers you will need to maintain it.

Are you sure they want 40W oil in the hydraulics, not an ISO grade 46? The better UTFs should be available. Several states have banned the sale of the UTFs labeled 303 as there is no 303 spec.

Without seeing how bad the damage is, I would say a good shop should be able to help you with the cylinder, as markct posted.
 
The fitting is broken such that it took some welded part and a piece of the cylinder casting with it. I called around about retubing and most places- even off in in Indiana and serious farm country said "Replace it." I'd sent them pictures.

I've considered breaking it down and brazing it. It'd be a little more life out of it.

Thank you
 
Do not have an operators but I have the service manual on the way.

I was hoping someone could give me the idiot's guide version as to what the pump on this straight shift dozer does ?

Thank you sir.
 
You do no have to tear the cylinder down, just push the piston back to the other end , keep wet rags around the place you are brazing and go slow. You can fix that part. Not sure why the guy thinks the pump and clutch are related. Seems to me you have a mechanical bind there somewhere under the floorboard. Pull the floorboards out and look at the linkage, see if it is not binding somewhere.
 
The pump on the clutch housing is the booster for the clutch,steering,brakes and lubrication,if you lost all the oil do not run the engine till you repair the damage and replace the oil otherwise the pump will starve and seize,the brake cylinders I believe are steel,the steering is machined in the cover and no doubt a casting.
AJ
 
AJ: Thanks- you don't know how much. I had a paper service manual that walked off(with someoneone's help). That gave me the info I needed in regards to the pump. My new manual is on a flash drive and is still showing Monday delivery.
Everybody who's replied- thanks.


Pump may be gone. It seems to seize. I don't know if this is true but I keep getting told that one symptom of it not being able to boost the clutch is that the clutch once brute force engaged by the pedal gets stuck in position, and I'm cheating by taking a bar by pulling it up to get the tractor in motion.

I've been keeping the hydraulic fluid full.

I had one fella I called at a scrap yard and I asked him about a pump- I can buy new for that. He also kept worrying me because he kept mistaking my D20 for a powershift D21.

It was not a fun day. I removed the pump with significant difficulty and it seems to want to seize and then free up. I have considered seeing whether or not it is possible to rebuild it, see if it has spur gears inside with too much clearance and maybe either cut them on my TM/UM or buy them, but I remembered I don't know what factory clearance spec is for the impellers/gears inside the pump(have not opened it to see what the spot that is "rough" is).


I think I need a new pump. I went through the clutch linkage and sprayed every piece of it with Kroil's lubricant(not just the penetrating oil, their lube). I hit pivots and linkage with grease. If there was rust, I have a small sand blast gun- you take and hook it to air, it has a piece of HD hose that dangles down. I fill up a bottle of abrasive, put the hose in the bottle of abrasive(you can fill any old dry bottle with abrasive) and when I found any rust through out the linkage- I took it out. That's when I then reoiled everything and greased things up.

This is driving me bonkers.

I took the offending cylinder off, took the ram out, blocked off the hole with some tape, and after I'd removed the rust with wire wheel- I said you know- this might work. I got my small oxy-acetylene I've got some brazing rods with no flux, I've got a flux stick(it's like a putty stick) and you rub it where you want to braze, silver solder, or weld. I've figured out a way to hold everything together. Time to heat it up tomorrow in an oven(it's one that is dedicated for induatrial stuff- it was a stand up kitchen unit in a restaurant, an eye went out constantly- so the owned told me to take it for scrap, I didn't scrap it, I just use the over, not the eyes). It may work, it may go wrong.

Wish me luck.
 
Interesting that someone has fitted a Mitsubishi engine. I wonder if it's an S4E ,same engine as the BD2 dozers.

The main clutch has two clutch plates....proper adjustment is key to long life.Proper adjustment of the trans brake band is critical too.
Which is why manuals are necessary & continue to pay off thru the life of the machine.

Fix your oil issue before using the machine,then check all oils & clutch strainer.

Plenty of D20 info on the HEF forums too...
 

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