I am now beginning to wonder if this is an air issue at all anymore...
JD 2950 cab tractor clutch bleeding help!
Hey all, we have a JD 2950 cab tractor. Went to drive it and had half a clutch, won't disengage the engine. Seeing weeping around the master cylinder we suspected possible air-fluid exchange so we replaced the seals. We bled a lot of new fluid, the old stuff looked vile, through the bleed screw on the slave cylinder using a clean oil-can. We attach a clear hose full of brake fluid to the bleeder and then pump with the can once the bleed is open. Its supposed to force air up and out.
We tested the tractor and saw improvement, could actually drive it, but still had rough shifting on 1&2. Bled some more and got a couple more air bubbles out. Tested it again and now have a Very weak clutch. Can't do anything, just grinds if you try.
Just found out that this tractor has a HI-LO lockout, located under the cab, and so we've started bleeding from there instead because its past the slave and has a bleed screw.
Any tips on how to better bleed out infiltrated air?
NEXT DAY...
I tried something else I had read. We used a pry-bar to pry back on the slave cylinder's piston, then applied pressure from the clutch as we released pressure on the slave-cylinder piston. Once the clutch is to the floor and the slave rod is back, we release the clutch slowly.
This produced Alot of bubbles and a very weak clutch. A little more back-bleeding from the slave bleed made more bubbles and stiffened up the clutch. We've done this 6 times now with the same results, perhaps alittle less bubbles now. We've gotta eliminate the bubbles, so we'll keep doing this but we'll back-bleed from the bleed under the cab, the HI-LO lockout, instead. Any other ideas, anyone?
HOURS LATER...
From the amount of air that we were getting constantly from that method of slave-cylinder prying we decided that we must be leaking air into the slave cylinder when we release the clutch. I also heard something of a suction sound at the slave while the clutch is released. Is it possible that those are one-way seals for the piston in the slave that would allow air to force past? Is there any way that we can avoid creating that suction while releasing the clutch, like squirting fluid into a bleed screw while releasing the clutch?
I still don't think that the slave seals are shot because the slave was dry and clean when we started this game. The rubber boot on the piston was shot, but it was clean, too. Any ideas or alternative methods would be appreciated!
NEXT MORNING...
Got some papers from JD describing bleed process. Not any different than what we have been doing. People say that this is difficult, but should it take multiple hours?? With no real results?
Thanks in advance
We tested the tractor and saw improvement, could actually drive it, but still had rough shifting on 1&2. Bled some more and got a couple more air bubbles out. Tested it again and now have a Very weak clutch. Can't do anything, just grinds if you try.
Just found out that this tractor has a HI-LO lockout, located under the cab, and so we've started bleeding from there instead because its past the slave and has a bleed screw.
Any tips on how to better bleed out infiltrated air?
NEXT DAY...
I tried something else I had read. We used a pry-bar to pry back on the slave cylinder's piston, then applied pressure from the clutch as we released pressure on the slave-cylinder piston. Once the clutch is to the floor and the slave rod is back, we release the clutch slowly.
This produced Alot of bubbles and a very weak clutch. A little more back-bleeding from the slave bleed made more bubbles and stiffened up the clutch. We've done this 6 times now with the same results, perhaps alittle less bubbles now. We've gotta eliminate the bubbles, so we'll keep doing this but we'll back-bleed from the bleed under the cab, the HI-LO lockout, instead. Any other ideas, anyone?
HOURS LATER...
From the amount of air that we were getting constantly from that method of slave-cylinder prying we decided that we must be leaking air into the slave cylinder when we release the clutch. I also heard something of a suction sound at the slave while the clutch is released. Is it possible that those are one-way seals for the piston in the slave that would allow air to force past? Is there any way that we can avoid creating that suction while releasing the clutch, like squirting fluid into a bleed screw while releasing the clutch?
I still don't think that the slave seals are shot because the slave was dry and clean when we started this game. The rubber boot on the piston was shot, but it was clean, too. Any ideas or alternative methods would be appreciated!
NEXT MORNING...
Got some papers from JD describing bleed process. Not any different than what we have been doing. People say that this is difficult, but should it take multiple hours?? With no real results?
Thanks in advance
1 - 16 of 16 Posts
Bleeding these are a real pain, but it shouldn't take as long as you are describing. I am wondering if your master cylinder is really ok. I usually replace the entire cylinder rather than rescaling it since the bore often is worn and new seals don't always work. I also eliminate the hi Lo lockout. Remove the line and cap off the fitting so no fluid can leak out. This simplifies the bleeding considerably. The lockout never really served any useful purpose anyway, deere eliminated it on the 2955.
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Hi there. When I replaced the master seals and slid the piston back inside I could feel the seals creating resistance to being slid in and out. Of course the spring was working also, but when I let the spring push the piston back out at me it seemed to have resistance.
Would you recommend leaving the Hi-Lo interlock shift unit disconnected permanently, or would you hook it up after your done?
Ever since we got this tractor early this spring it hasn't been a real smooth shifter. You kinda have to hold your tongue the right way, esp when shifting into high range. Is it possible that this isn't an air issue at all? Or has there always been alittle air that suddenly got worse? I'm just scratching my head here...
Thanks for the info!
Would you recommend leaving the Hi-Lo interlock shift unit disconnected permanently, or would you hook it up after your done?
Ever since we got this tractor early this spring it hasn't been a real smooth shifter. You kinda have to hold your tongue the right way, esp when shifting into high range. Is it possible that this isn't an air issue at all? Or has there always been alittle air that suddenly got worse? I'm just scratching my head here...
Thanks for the info!
I copied & pasted this from another tractor forum. I hope the original author doesn't mind.
The trouble is that the slave cylinder is designed to only hold pressure one direction. The way you are trying to use it as a pump WILL NOT WORK!!!! It will suck in AIR 100% of the time.
Also who ever told you to bleed from the bottom is Wrong. You have to push the oil from the top down. The way the slave cylinder sets will allow an air pocket in it. You can't push it back up.
Also the way you are trying to bleed the slave cylinder retracted will work IF you do it correctly. Which you are not doing. With the slave cylinder pushed in all of the way you are making the volume smaller. This is easier to bleed. So here is how you would do it.
1) Hold the slave cylinder in all of the way.
2) Bleed it like you would normally. Meaning push the pedal and open the bleeder. Bleed like normal.
3) Where you are making a mistake. DO NOT let the slave cylinder out while the pedal is down. The pedal will force the slave cylinder out some when there is not air but do not let it move all the way out while the pedal is held down. Just make the fluid push you out some. Then let the pedal up. This opens a port to the reservoir. NOW let the slave cylinder out. It can suck the fluid down from the reservoir this way. The way you where doing it with the pedal held down makes the slave cylinder pull a vacuum on the system. There is no way for it to pull more fluid with the pedal held down. So it is more than likely pulling outside air in or air from the lock out cylinder.
Here is how I have always done them manually.
1) You can try to bleed the slave cylinder before rebuilding it. Just put your line on the bleeder. The other end has to be submerged in fluid. Have the bleeder open a little bit. Pump oil(with the pedal) through it until you are not getting any more air. LOCK the bleeder. !!!DO not push the pedal at this time!!! IF you do you will suck the air out of the lockout cylinder and have to start all over. Leave your line on the bleeder and the end submerged.
2) Put a second line on the bleeder on the lock out cylinder. Open the bleeder THEN start pumping fluid through it until you do not see any more air. LOCK the bleeder !!Again do not push the pedal any more now!!!
3) Move back to the slave cylinder. Open the bleeder and THEN push the pedal. You may see a little more air but it should not be much less.
4) Go back to the lock out and bleed it again.
You need to move fluid and air first. If you keep pumping the cylinders they work air back and forth between them and it will take longer to bleed them. So by using the hoses you can move the fluid and air in the cylinders without moving the cylinder pistons.
Work back and forth until you are not getting any more air. Then lock both bleeders and push the clutch down. You should have full pedal now. If you don't then the slave cylinder will have to be rebuilt. The kit is about $100 just for the piston.
You can get the air out this way it just takes time. LOTS of time. I have spent a day getting all of the air out manually.
Here is how I do it now. I have a pressure tank that holds about a gallon of brake fluid. It has a hose I hook where the reservoir usually goes on the master cylinder. The I apply about 5 psi air pressure to the tank. Then I go down to the slave cylinder and open the bleeder until I get ZERO air. The open the lock out cylinder bleeder until I get no air. Then I take my tank off up top. I then fill the reservoir while I have the line clamped. I hold my finger over the line and remove the clamp. I put the line back on the master cylinder while it has fluid pressure pushing any little bit of air out of it.
I can usually get the system bleed in under an hour this way. Email me if you want and we can exchange PH# and I can maybe talk you through doing it.
The trouble is that the slave cylinder is designed to only hold pressure one direction. The way you are trying to use it as a pump WILL NOT WORK!!!! It will suck in AIR 100% of the time.
Also who ever told you to bleed from the bottom is Wrong. You have to push the oil from the top down. The way the slave cylinder sets will allow an air pocket in it. You can't push it back up.
Also the way you are trying to bleed the slave cylinder retracted will work IF you do it correctly. Which you are not doing. With the slave cylinder pushed in all of the way you are making the volume smaller. This is easier to bleed. So here is how you would do it.
1) Hold the slave cylinder in all of the way.
2) Bleed it like you would normally. Meaning push the pedal and open the bleeder. Bleed like normal.
3) Where you are making a mistake. DO NOT let the slave cylinder out while the pedal is down. The pedal will force the slave cylinder out some when there is not air but do not let it move all the way out while the pedal is held down. Just make the fluid push you out some. Then let the pedal up. This opens a port to the reservoir. NOW let the slave cylinder out. It can suck the fluid down from the reservoir this way. The way you where doing it with the pedal held down makes the slave cylinder pull a vacuum on the system. There is no way for it to pull more fluid with the pedal held down. So it is more than likely pulling outside air in or air from the lock out cylinder.
Here is how I have always done them manually.
1) You can try to bleed the slave cylinder before rebuilding it. Just put your line on the bleeder. The other end has to be submerged in fluid. Have the bleeder open a little bit. Pump oil(with the pedal) through it until you are not getting any more air. LOCK the bleeder. !!!DO not push the pedal at this time!!! IF you do you will suck the air out of the lockout cylinder and have to start all over. Leave your line on the bleeder and the end submerged.
2) Put a second line on the bleeder on the lock out cylinder. Open the bleeder THEN start pumping fluid through it until you do not see any more air. LOCK the bleeder !!Again do not push the pedal any more now!!!
3) Move back to the slave cylinder. Open the bleeder and THEN push the pedal. You may see a little more air but it should not be much less.
4) Go back to the lock out and bleed it again.
You need to move fluid and air first. If you keep pumping the cylinders they work air back and forth between them and it will take longer to bleed them. So by using the hoses you can move the fluid and air in the cylinders without moving the cylinder pistons.
Work back and forth until you are not getting any more air. Then lock both bleeders and push the clutch down. You should have full pedal now. If you don't then the slave cylinder will have to be rebuilt. The kit is about $100 just for the piston.
You can get the air out this way it just takes time. LOTS of time. I have spent a day getting all of the air out manually.
Here is how I do it now. I have a pressure tank that holds about a gallon of brake fluid. It has a hose I hook where the reservoir usually goes on the master cylinder. The I apply about 5 psi air pressure to the tank. Then I go down to the slave cylinder and open the bleeder until I get ZERO air. The open the lock out cylinder bleeder until I get no air. Then I take my tank off up top. I then fill the reservoir while I have the line clamped. I hold my finger over the line and remove the clamp. I put the line back on the master cylinder while it has fluid pressure pushing any little bit of air out of it.
I can usually get the system bleed in under an hour this way. Email me if you want and we can exchange PH# and I can maybe talk you through doing it.
Thanks Jim. I saw that too, because that is also my other thread, 
. I have just been trying it and I think that my slave seals are shot. I can hear air sucking into the slave with every stroke of the clutch.
Most likely will order seals before going any further.
. I have just been trying it and I think that my slave seals are shot. I can hear air sucking into the slave with every stroke of the clutch.Most likely will order seals before going any further.
I would leave the interlock disconnected permanently. One thing I don't like about it is it can also leak and let air in the system and it will leak into the transmission and you will never see it. Also it doesn't serve a useful purpose other than preventing you from accidently
shifting the hi Lo when shifting gears 1 - 4. Every time I bleed one of these I disconnect the interlock and customers report improved shifting of hi Lo. I doubt your slave cylinder is letting in air if it isn't leaking fluid. Possible I guess. When you push in the clutch, how much travel are you getting from slave cylinder? Should be minimum of 5/16". If you are getting at least that much travel, then air is not your problem. More likely a clutch problem.
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shifting the hi Lo when shifting gears 1 - 4. Every time I bleed one of these I disconnect the interlock and customers report improved shifting of hi Lo. I doubt your slave cylinder is letting in air if it isn't leaking fluid. Possible I guess. When you push in the clutch, how much travel are you getting from slave cylinder? Should be minimum of 5/16". If you are getting at least that much travel, then air is not your problem. More likely a clutch problem.
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I guessed it was from the same author but it had a different "handle"Thanks Jim. I saw that too, because that is also my other thread,
Most likely will order seals before going any further.
Username already taken, so needed new one
Well, the seals are coming this morning so I guess today is The Day Of Truth! : )
Well, no seals came yesterday. A bit of a disappointment, but they should be in tomorrow. I'll have my go at it then.
Jay Dee ordered the wrong kit. He can only order by looking at a picture and thought he got it right. Nobody in town has a seal that will match. So we took the piston off the slave to get it machined so that it will fit a regular hydraulic seal. After all this hopefully we can successfully bleed this thing.
Having spent some time working behind a JD parts counter I can state that sometimes looking up correct parts can be difficult. I was taught to always read part descriptions & footnotes. Ordering an AL37515 Piston Replacement Kit subbed to the 3 following PN'sJay Dee ordered the wrong kit. He can only order by looking at a picture and thought he got it right. Nobody in town has a seal that will match. So we took the piston off the slave to get it machined so that it will fit a regular hydraulic seal. After all this hopefully we can successfully bleed this thing.
Part Number:Qty.Description
AL37519 1 Tune-Up Kit
AL37520 1 Kit
AL37521 1 Bleed Valve
Replaces Part: AL37515
Description: Piston Replacement Kit
Attachments
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86.3 KB Views: 828 -
30.5 KB Views: 366
1) You can try to bleed the slave cylinder before rebuilding it. Just put your line on the bleeder. The other end has to be submerged in fluid. Have the bleeder open a little bit. Pump oil(with the pedal) through it until you are not getting any more air. LOCK the bleeder. !!!DO not push the pedal at this time!!! IF you do you will suck the air out of the lockout cylinder and have to start all over. Leave your line on the bleeder and the end submerged.
2) Put a second line on the bleeder on the lock out cylinder. Open the bleeder THEN start pumping fluid through it until you do not see any more air. LOCK the bleeder !!Again do not push the pedal any more now!!!
3) Move back to the slave cylinder. Open the bleeder and THEN push the pedal. You may see a little more air but it should not be much less.
4) Go back to the lock out and bleed it again.
You need to move fluid and air first. If you keep pumping the cylinders they work air back and forth between them and it will take longer to bleed them. So by using the hoses you can move the fluid and air in the cylinders without moving the cylinder pistons.
Work back and forth until you are not getting any more air. Then lock both bleeders and push the clutch down. You should have full pedal now. If you don't then the slave cylinder will have to be rebuilt.To quote JD Seller's advice to me before as a reference for the reason I did this.
I put the slave cylinder back together with the new, very stiff!, hydraulic seal in place of the old seal. It is now so stiff inside the cylinder that I cannot push the piston in with my thumbs, neither can the spring push it back at me. I can move it if I step on it. Is this too tight?
While I was at it I also took off the line to the Hi-Lo interlock and sealed off both the slave and the interlock. I filled the slave cylinder with brake fluid and attached my clear hose, full of brake fluid, to the bleed screw with the other end in a jar, submersed in fluid. The jar is slightly lower than the bleed, with a hump in between them that is higher than both ends. I ensured that the reservoir was full and opened the bleed a 1/3 turn. Instantly bubbles started to emerge from the bleed and caught in the hump.
I slowly depressed the clutch and got a horde of bubbles with virtually no fluid. The air forced all the fluid in my hose out the end, so when I went to slowly release the clutch I sucked a hose-full of air back into the slave! I tried again, but this time I filled the hose with fluid again before I released the clutch. I sucked no air back this time, but when I checked the fluid level in the reservoir the level had not gone down. I have done this 5 times now and have seen no fluid drop.
The good news is that I cannot hear air being sucked past the slave seals anymore!
I also noticed, however, that if I leave the whole setup alone with the pedal up that it will slowly gravity-feed down and out the whole system. The fluid in the reservoir goes down, and I can see air bubbles slowly coming up thru the fluid in the jar.
So, I am wondering a couple of things. I am thinking that pumping the pedal as I am is not working. So, perhaps I need to raise the jar above the slave, switch it out for a large funnel, switch out for a bigger hose, and fill the funnel with fluid. I wonder if that would help keep the air up away from the bleed and the hose full of fluid. This will not help the level in the reservoir go down, tho.
I am also wondering if I should somehow add to the reservoir to make it alot higher in an attempt to gravity-bleed the whole system from the top. I am afraid that this method will be too slow and leave air pockets in the bends and in the cylinders. I am no longer sure where all my air might be, so I am assuming that I have air everywhere.
I am also wondering if I can make a home-made version of your pressure-tank bleeding system. I'll look into it, but not sure if I can.
So, now that I have written a book I am awaiting advice!
Actually, bleeding the system backwards from the slave cylinder and the lockout cylinder is the recommended method. Attach a long hose to the bleeder on the lockout culinder with a small funnel. Fill the funnel with fluid while holding it higher than the master cylinder. Gravity should push fluid backwards through the system. When no more air bubbles come into the master cylinder, close the bleeder and then attach to the slave cylinder and repeat the process. Sorry it didn't occur to me that you weren't doing that earlier.
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Success!! Here's what I ended up doing.
I changed the hose that leads from the reservoir to the master cylinder after finding 4 big cracks in it.
I just kept bleeding the system the conventional way you bleed brakes. The interesting thing was that I often had to play with how I released the clutch to get the fluid from the reservoir to flow down.
After a couple hours I was about to give up, as the flowing of the fluid was getting trickier to keep up and I still seemed to be able to occasionally squeeze little bits of air out, but I decided to try the clutch before I tried the other method.
It was stiffer than it has been since we started this game, and so I started it up. All the gears shift as smooth as hot butter, even better than when we got the thing! I took it for a little spin and had absolutely no trouble shifting to-and-from any gear.
It's fixed!! Thanks everyone for posting, and I appreciate all the advice that you guys have given me!! Especially JD Seller. Your tips were what did it!
Here's where the main discussion has taken place: http://forums.yesterdaystractors.com/viewtopic.php?t=1058206
I changed the hose that leads from the reservoir to the master cylinder after finding 4 big cracks in it.
I just kept bleeding the system the conventional way you bleed brakes. The interesting thing was that I often had to play with how I released the clutch to get the fluid from the reservoir to flow down.
After a couple hours I was about to give up, as the flowing of the fluid was getting trickier to keep up and I still seemed to be able to occasionally squeeze little bits of air out, but I decided to try the clutch before I tried the other method.
It was stiffer than it has been since we started this game, and so I started it up. All the gears shift as smooth as hot butter, even better than when we got the thing! I took it for a little spin and had absolutely no trouble shifting to-and-from any gear.
It's fixed!! Thanks everyone for posting, and I appreciate all the advice that you guys have given me!! Especially JD Seller. Your tips were what did it!
Here's where the main discussion has taken place: http://forums.yesterdaystractors.com/viewtopic.php?t=1058206
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