Clutch Pedal Has No Resistance, Help Diagnose Problem

I've got an 81' CJ5 and I'm trying to figure out this issue with the clutch. Note that until now the Jeep has been sitting for 6-7 years.

When I press the pedal there is no resistance. I put more brake fluid in the master cylinder and nothing. Then I disconnect the hydraulic line from the slave cylinder and when I press the pedal some brake fluid comes out.

The slave cylinder push rod is in contact with the clutch fork but it doesn't move at all when I'm pressing the pedal.

I've order a new master cylinder, slave cylinder, and clutch line to replace them all and see what happens. I will add that for now I'm able to turn the Jeep off, put it in first, and then start it and it will be in gear driving but that's all I can do at the moment.

 

Sounds like the clutch is out likely. That’s what the pedal felt like on mine when it blew out in a busy intersection haha

 

Definitely possible. I've never swapped a clutch so that'll be interesting if it's the case. But what I don't understand is the push rod doesn't move at all when I press the pedal down. I thought how the hydraulics work is the added fluid flow pushes the piece inside the slave cylinder, which extends the push rod and the pushes the clutch fork. In my head I'm thinking I haven't even used the clutch because I can't seem to get it detached yet.


Is it possible to depress a clutch fork by hand? Could it be stuck somehow from sitting so long? Considering tapping it with a hammer or finding a way to loosen it up

 

I would point to the hydraulic clutch rather than the clutch plate itself. If the slave does not move with the master, you have no hydraulic action. That's kind of obvious. You can have fluid in the reservoir, but if the seal around either piston is kaput, nothing will happen.

 

x2. Probably the clutch its self is fine, look to the slave and master cyl for your problem.

 

That's what I was thinking, I'll be swapping in a new LUK master and slave this weekend, new clutch hydraulic line as well. Apart from taking off the old stuff and putting in the new, are there any specific steps with this install? Couldn't find anything on Youtube. The new slave came with the push rod by itself, when I install do I just set it inside the rubber boot as far in as it goes?

 

You will need to bleed the system to remove air. I would bleed and test before I replaced any parts. Bleeding and adjustment will be covered in the TSM. You need the TSM.

There is most of an '82 TSM here: Jeep® Parts Manuals online You can buy the '81 TSM (better for you) on CD-ROM More Information for DETROIT IRON DCDC113 or as a paper copy on the same site.

 

I have a PDF of the 81' TSM I've been using. I tried to bleed the system initially but I was doing it for about an hour and couldn't make any progress. (Loosen bleeder screw, press pedal in and hold, tighten bleeder screw, release pedal.) I ran some clear plastic tubing from the slave into a water bottle with brake fluid in it to watch for bubbles and they never went away.

 

My guess - master cylinder is fully leaky internally. No hydraulic pressure since it's all leaking past the cylinder. It'll pump fluid out into the air, but won't make enough pressure to move the slave.

 

That sounds about right, and with their not being the proper pressure to move the slave and push the plate, would that also be why my pedal has no resistance when I press down?

 

I can press down to the floor and it will return to it's original position (I believe because of a spring attached to it's mechanism) but pushing it in there's just no feeling it's loose.

 

It’s pooched. new master slave and line should solve that problem.

 

Thanks all, will update when I get those replaced.

 

Okay so I replaced the clutch master cylinder, slave cylinder and hydraulic line. I ran into a problem during installation. The clutch plate that the push rod sets in does not return to it's original position after I push down on the pedal. I got the system bled and the hydraulics reach the slave cylinder and push the plate back but I had to use a rubber bungee cord to pull it back into position.

I can see a small hold on the end of the clutch plate where possibly a spring is supposed to hook in, but I don't know where the other end of the spring would go. Reading online I found that a clutch fork return spring is in fact a thing but I don't know which one I need to buy or where to install it.

But at least I got to drive the jeep around and go through the gears.

 

Woohoo!

The plate is the disk that goes against the flywheel. Also called a clutch disk. The clutch cover pushes the disk against the flywheel. The lever that moves the clutch is called the throwout arm or lever. It moves the throwout bearing or sleeve which pushes against the fingers of the cover to release the clutch. The lever rests on the pivot in the bellhousing.

There should be a spring from the end of the lever to a tab with a hole on the bell housing. Mostly this keeps the adjustment screw in the pocket on the lever. Most of the return action should come from the springs in the cover, and the return spring (over-center spring) on the pedal under the dash.

Get an assortment of springs and pick one that fits. Dorman Products - Search Results Any parts store can get Dorman stuff the next day, or you can order by the number on Amazon or RockAuto.

You don't need a lot of pressure here. A throttle return spring (lighter gauge) might be better - Dorman Products - Search Results

 

My bad so the push rod sets in the throwout arm, and the throwout arm is supposed to attach via spring to the inside of the bellhousing to keep the arm against the pivot. But I feel this doesn't address the problem I'm having.

Before I installed the new slave cylinder, I could reach down and press the throwout arm back (towards the tailgate) and it would just stay there. I would have to reach down again and pull it forward to put it back in place. This is how I realized there should be something constantly pulling it towards the front and I don't think a spring running into the bellhousing could do that.

Are you sure the spring doesn't go from the end of the throwout arm to the slave cylinder somehow? This way the springs trajectory is pulling it right back in line with the push rod?

 

I looked all over my slave cylinder for somewhere to put the other end of a spring and couldn't find anything so I guess I'll have to keep researching

 

yes the spring pulls the release arm forward there is often a hole or bracket with a hole just if front of the arm on the bellhousing.

 

Something like

Do you think you could link the spring that I need? Or at least what it looks like. I’m seeing so many different types on quadratec.

For 1981 CJ-5, 2.5L 4 cyl and SR4

I’ll have to look where it goes on the bell housing next time I go I hope I can find it. But as for right now I have no idea how big of a spring I need or length.

 

Crown 3236804 Hydraulic Clutch Slave Cylinder Return Spring, 1980-86 Jeep CJ Models | Bernie's CJ Jeep Parts