Tractor clutch issue has everyone baffled, please help!

Looking for some opinions on an issue. Tractor was having an issue with the clutch, sometimes you would have to pump the clutch pedal to get the clutch to disengage so you could put it into gear. Also the clutch pedal would stay on the floor and not return to up position. They diagnosed it and wanted me to put a clutch, pressure plate, master cylinder and slave cylinder w/ throw out bearing in it as well as pilot bearing. I had to put a rear main seal in it anyways for an oil leak. Took all the old parts to New Holland dealer w/ the SN and all, they gave me the new style slave cylinder and pressure plate with clutch as well a master cylinder and bearing. Put it all back together, bled the system with the correct LHM fluid from CNH. Same issue nothing changed. When I bleed it I'll get good pressure from the bleeder valve, and then the pedal will stay on the floor and nothing. Doesn't seem like it is acting on the pressure plate as much as it should either. No leaks, no air bubbles, even tried to vac bleed it from both ends. Split the tractor again and sent the parts back assuming the pressure plate was bad. They called me back and said it should all be correct and to bring my flywheel down and they can check everything with engineering. So that is what I did, they called me back saying everything is within spec. Seems odd to me the pressure plate fingers are setting in towards the flywheel noticeably when its all bolted up. Looking for someone with experience with these tractors, the issue seems to be alluding all of us over here. Of course it has a massive side boom mower on it blocking the view port for the bellhousing when the tractor is assembled... New Holland 6640 SN: 081039B Variante 963230000-12X12 TRANS W/IPTO 540 Clutch 82011591 (CNH) Pressure plate 82011590 (CNH) Slave cylinder 47134440 (CNH) Master cylinder 1101-1550 (Atlantic parts)

Does this tractor get any pressure from the hyd,trans. system itself? If so is that press. correct. Had a very similar problem on a municipality cat challenger with a sideboom.

I don’t believe it does for the clutch itself. It’s a pedal actuated clutch with a master and slave cylinder. It shares a fluid res with the brake system. Only lines to the master cylinder for the clutch go down to the slave cylinder and fluid res.

Does the master cylinder push rod have free play? Might be blocking the compensation port?

Its been several years ago but it had a valve where it tied into the tractor system and this valve was bad and was causing the pedel to stay down sometimes

If I push the slave cylinder in all the way, the rod coming from the master cylinder has some play, for example I can pull the pedal up a small amount. What I’m trying to say is there isn’t any tension on the rod so I believe it is able to travel the entire way out

This sounds like the common problem Ford trucks have. The hydraulic clutch system is very difficult to get all the air out. What works most of the time on them, you get as much air out with the bleeder as you can, and then you turn the engine off, crank it up in gear and go for a ride. Hills lumps and bumps work the best, any air left in the system will slowly work it's way backwards up to the reservoir. The engine vibration and driving it around helps work the bubbles backwards. You can try it and see if it gets any better. Since you are able to pump it up and make it work, that is a sign you are almost there.

franklin2 said: This sounds like the common problem Ford trucks have. The hydraulic clutch system is very difficult to get all the air out. What works most of the time on them, you get as much air out with the bleeder as you can, and then you turn the engine off, crank it up in gear and go for a ride. Hills lumps and bumps work the best, any air left in the system will slowly work it's way backwards up to the reservoir. The engine vibration and driving it around helps work the bubbles backwards. You can try it and see if it gets any better. Since you are able to pump it up and make it work, that is a sign you are almost there. Click to expand... I’m pretty sure this is the same as a Ford tractor. Air is what I thought as well. I thought I ruled this out pulling a vacuum on both the bleeder valve and the reservoir cap. I’ll give this a go if nothing else turns up and I slam it all back together again.

Used a jig to keep the flywheel/clutch/pressure plate on the input shaft without bolting the engine back up. When the pedal is pushed to the floor its bleeding pressure off. If you hold it there eventually you can just spin the flywheel. No leaks. Has to be faulty master cylinder I am out of ideas

Bullitt said: Used a jig to keep the flywheel/clutch/pressure plate on the input shaft without bolting the engine back up. When the pedal is pushed to the floor its bleeding pressure off. If you hold it there eventually you can just spin the flywheel. No leaks. Has to be faulty master cylinder I am out of ideas Click to expand... It shouldn’t bleed off so your probably correct

A possible just because new doesn't mean it's good scenario causing allot of back tracking.

Truck Shop said: A possible just because new doesn't mean it's good scenario causing allot of back tracking. Click to expand... old mentor used to say "new just means never tested"

Bullitt said: old mentor used to say "new just means never tested" Click to expand... Truth at it's best.

Air can be a problem. Did you bench bleed the master? Then the slave would have to be bleed I guess by pumping the clutch and letting air out while you keep the reservoir full. I think if you plug off the master and push down on the clutch if no oil comes out and the pedal bleeds down you have a bad master. Pictures might help to get it in our minds a little better. Always best to take five and think out of the box for awhile before you take anything apart again. Wish you the best. At least you could tell your parts people you eliminated everything else out of the system and they could do a bench test.

I have never done that exact tractor but many other vehicles with hydraulic clutches. European Volvo and Renault Mack cab overs. F series Fords. Some little trucks. A Challenger tractor. Isuzu maybe a Kabota. Last one was a 1988 F350 last week. I was working with a young buck a few years ago. He was putting a clutch in a Mazda Ranger and had the master slave and connecting line all together. Held up the master and was tapping on the slave and line. Asked what are you doing? He said it is full of fluid. As I move the slave and the line around all the air will work out to the top as I tap on it. He put it all together and it worked perfect. Then there was my damn 2001 Dodge. I bought it new. Hydraulic clutch was not working. Replaced the slave or the master. Then the other as it would not work. The slaves had no bleeders at that time. Tried to bleed it through the slave line. Finally got it to half ass work and it worked out in time. Had to have it in gear when started for a while or it would not go into gear. Then the slave started seeping fluid. I carried a little bottle of brake fluid in a cubby on the welder for years. Right behind the drivers door. If the clutch felt funny fill it up right now. It would work out in time. A year or so ago it had ran its course and I called to order parts. Now they come both cylinders with connecting line and bleed out. Just put the whole thing in. It worked great. Kick myself for not knowing that was available. Still have that truck and running the original clutch. A couple of other ways I have done them was to buy a new thumb pump oil can. Fill it up with brake fluid and pump it all out to clean it. Then use it to pump fluid into the slave cylinder to fill the whole system. Do not let it run out of fluid. That was shared to me by a friend, not my idea but it has worked for me. The other is to fill the master and put the cap on without the rubber under it. Then use an air blower through the vent hole in the top of the cap. Be easy, do not run it out of fluid, 2 or 3 times normally gets you enough pedal to go. Had to do that with the F350 as you cannot put it all together and install it. Thought about trying the vacuum deal but just went back to what I know. Hate you hear you have done so much likely due to air in the hydraulic clutch. I have been there they can be really difficult. Good luck.

Bullitt said: If I push the slave cylinder in all the way, the rod coming from the master cylinder has some play, for example I can pull the pedal up a small amount. What I’m trying to say is there isn’t any tension on the rod so I believe it is able to travel the entire way out Click to expand... I also had a F700 kick my butt. Replaced the master cylinder and it worked fine at first. The short is the depth in the hole for the brake pedal rod was different from the new one to the old one.

Forgot to update this, new master cylinder was faulty, replaced and the machine has been back in service for a while now with no issues

Bullitt said: Forgot to update this, new master cylinder was faulty, replaced and the machine has been back in service for a while now with no issues Click to expand... New just means never tested as you Posted. Glad she is fixed. Simon C