Clutch piston too short?

there are different ways to bench bleed the master depending on the tools available to you... did you receive a fitting, with or without a port for a small hose, in the new master box? if not then you should make one or get one at the parts store. you need to put the master in a vice (from the mount, not the body) and fill it with fluid. this is where the fitting comes in handy, you are going slowly depress the piston about half way at first having the fluid that comes out the port directed back into the reservoir with a hose. keep the hose submerged. if a vice and fittings are not available, you can mount the master in the vehicle, connect the line and fill with fluid. disconnect the line from the slave cylinder and submerge it in a container. press the pedal by hand slowly. make sure the line stays submerged and the master is never run dry. if everything is kept clean, you can reuse the fluid from the catch container.

Check the hydraulic clutch operation. This is a clutch master cylinder with a reservoir on the firewall, and a clutch slave cylinder down on the bell housing of the transmission, with a steel tube running from the master to the slave cylinder. When clutch pedal is depressed, hydraulic fluid (brake fluid) is forced from the master to the slave. The slave cylinder should push out a little plunger that contacts the clutch fork lever-pushing it forward to engage the clutch.
Add brake fluid to the reservoir if needed. Watch the plunger on the slave cylinder: if it moves little, or not enough, try bleeding the slave from the bleeder valve. They are bled just like brakes. If bleeding doesn't help, your clutch master or the slave may need replacing. The master cylinder, like a brake master, has internal seals that hold hydraulic pressure, so force can be applied to the plunger on the slave cylinder.

Your clutch slave cylinder could be bad and leaking,here's a picture of it,it's bolted to the side of transmission,has a bleeder screw on it for bleeding.Normally,your fluid shouldn't be low,here's how to replace.

See instructions below from autozone.com. If the clutch still has air after following this procedure, try back bleeding by pushing the slave piston in while the bleeder is open, then closing bleeder before releasing the piston. This is similar to bench bleeding the slave, in case you didn't do that before the installation.

HYDRAULIC SYSTEM BLEEDING This operation must be performed any time the clutch master or slave cylinder has been removed or if any of the hydraulic lines have been opened.

WARNING Do not spill brake fluid on the bodywork of the vehicle; it will destroy the paint. If fluid is spilled, immediately wash the surface with plenty of clean water.

1. Fill the master cylinder reservoir with brake fluid.
2. Remove the cap on the bleeder screw on the clutch slave cylinder. Install a clear vinyl hose on the fitting; place the other end submerged in a clear glass jar partially filled with brake fluid.
3. Have an assistant pump the clutch pedal slowly several times. After several pumps, hold the pedal down and open the bleeder, allowing fluid to flow into the jar. Close the bleeder valve almost immediately after opening it. Release the pedal only after the bleeder is closed.
4. Repeat the process until the fluid in the hose contains no air bubbles. tube. When there are no more air bubbles in the system, tighten the plug fully with the pedal depressed. Replace the plastic cap.
5. Fill the clutch master cylinder reservoir to the correct level with brake fluid.
6. Check the system for leaks.

Sounds like the seal in the new clutch master cylinder. I've seen that same problem in the hand brake system in small 2 and 4 seat airplanes. ( I'm and aircraft mechanic) The problem is not air in the lines so bleeding won't help. The piston seal is intermittantly failing to seal. That is whty the function can return without any apparent reason as the seal has seated itself. The only cure is to replace or rebuild the master cylinder. ( Yes, even new or rebuilt ones can have a defective or improperly installed piston seal)

Hope this helps

You should be able to buy a rebuild kit for the cylinder, I would rebuild the slave and master. just take it off, take the snap ring off and remove the piston, make a note of which direction its facing, the new one may come with a piston with the seal aready installed.The cup will have the flare facing forward. Just put the new seal on/ or piston in and reseat the snap ring. The slave is just as easy. then you want to bleed all the air out. Fill master cylinder and open the slave bleeder screw, just let fluid come out until all the air bubbles quit. that should bleed it. If the pedal dosent feel right, you may need to have another person depress the pedal and then open the bleeder.

they use a hydrolic system wich use fluid if your gears are not grabbing and its slipping no udjucment require because the cluck is bad but if you cant put it in gear when it on then its your hydrolic system

Replace both clutch slave and master cylinders, and bleed well. I've also had this happen.

dude under truck left hand sideof tranny, is your clutch slave cylinder, remove the hydraulic line, the two mount bolts. replace the slave cylndr. you got clutch !!!!

ps i dont recall there being a bleed valve. it should bleed by gravity


james ray

Removing and replacing is straight forward mechanic work.Here is a gotcha that very few manuals will tell you,but years of experience will teach you.Go ahead and install the clutch slave cylinder on the bellhousing of the trans.The clutch master cylinder needs to be "bench bled" so that as much air as possible is gone from the master cylinder before installed on the vehicle.This requires a helper.Take master cyl. to a bench and set it down while holding the assembly in your hands.Fill the reeservoir with brake fluid.I wear latex or nitrile gloves while i work to keep my hands clean.This helps in sealing off the output fluid port during this procedure.Have your assistant take a phillips head screwdriver and push the piston in,on the master cyl and hold it in the depressed position.Some fluid and air will shoot out the output port.Now take your latex glove clad finger,and press it firmly over the fluid output hole.Now release the screwdriver.Remove finger from hole,and stroke the piston in with the screwdriver and hold it at it's depressed position.Place finger over the hole.Add fluid to the reservoir.Keep repeating until only solid fluid exits the output hole.This is bench bleeding.Now install into vehicle being careful to not get brake fluid on the paint.After installing,on the clutch master cylinder rod...there is a jam nut,either 12 mm or 14 mm.Loosen this nut and back it off.Now,the threaded rod can be spun in,or out,making the rod shorter or longer.this is how you adjust the clutch pedal engagement point,after installation.Back to the clutch master and slave,they obviously need to be bled after installation,with the bleeder valve down on the slave cylinder.Good luck.