Clutch Hyd. Fluild

[trackitman]

Recently my clutch pedal has been sloppy and not as resistant when depressing. After seeing the master cylinder empty of fluid, I crawled under the car to inspect the slave cylinder. I could not see any leaking fluid on the slave, the line leading to the slave, or the master. I do, however, have a relatively new leak in the center of the car where the bell housing and the engine meet. Could the slave be leaking inside the bell housing, with the oil running down inside the bell housing to the center, then exiting?

I'm about to pull off the slave, but wondering if anyone has seen this kind of problem.


Thanks!

 

[Ken]

Could the slave be leaking inside the bell housing...

No, the hydraulics are all external. When was the last time you checked your fluid level? It may have been low for a while and the signs are just now beginning to show up.


Ok, I'll add what the book says about routine inspection checks one should perform:

There are several things which affect good clutch operations. Therefore, it is necessary, before performing any major clutch operations, to make preliminary inspections to determine whether trouble is actually in the clutch.

HYDRAULIC CLUTCH SYSTEM
The hydraulic system consists of a master cylinder and a slave cylinder. When pressure is applied to the clutch pedal (pedal depressed), the push rod contacts the plunger and pushes it up the bore of the master cylinder. In the first 1/32 of movement, the center valve seal closes the port to the fluid reservoir tank and as the plunger continues to move up the bore of the cylinder, the fluid is forced through the outlet line to the slave cylinder mounted on the clutch housing. As fluid is pushed down the pipe from the master cylinder, this in turn forces the piston in the slave cylinder outward. A push rod is connected to the slave cylinder and rides in the pocket of the clutch fork. As the slave cylinder piston moves rearward the push rod forces the clutch fork and release bearing to disengage the pressure plate from the clutch disc. On the return stroke (pedal released), the plunger moves back as a result of the return pressure of the clutch. Fluid returns to the master cylinder and the final movement of the plunger lifts the valve off the seat, allowing an unrestricted flow of fluid between the system and reservoir.

Check the clutch to be sure the clutch releases fully as follows:

1. With engine running and brake on, hold the clutch pedal on the floor mat and move the shifter between first and reverse several times. If this can be done smoothly, the clutch is fully releasing. If shift is not smooth, clutch is not fully releasing and inspection is necessary.
2. Check clutch pedal bushings for sticking or excessive wear.
3. Check clutch fork for proper installation on ball stud. Lack of lubrication on fork can cause fork to be pulled off the ball.
4. Check slave cylinder and clutch pedal travel. The slave and clutch pedal cylinder should have 0.70" travel (measure travel at the clutch fork) with the clutch pedal fully depressed. The clutch pedal should have approximately 7-3/8" travel fully depressed.

_ken

 

[trackitman]

Ken - Just got the car this year, and today was the first time I checked it. Your theory could be right.

 

[Ken]

Blaise, look again; I've added a little more to my initial response.

_ken

 

[vigman]

If you were empty

You probably sucked air into the system..

I'll go get a post 4 U


Vig!

 

[vigman]

try this~ Clutch bleeding 101

Not bled correctly Clutch slave

The NOSE of the clutch slave is HIGHER then the bleeder valve when the slave is installed.

Air gets trapped in the NOSE of the slave cylinder.. and you wind up with not enough pedal.

The GRIND is the clutch not FULLY disengaging... when you put it in to a FWD gear..in reality you are STOPPING the input shaft fropm turning... then with a quick shift into reverse.. you do not grind.. but that is a band-aid if your stuck one night.

I'll bet you do not have the "Normal" amount of pedal now.. and the clutch disengages ONLY when your MASHING the pedal down.

Here's the trick.

1) Loosen, quickly the bleeder then just get it snug, so it will be easier to undo when the slave is unbolted from the side of the Bell housing.

2) Remove the linkage rod from the slave to the clutch fork.

3) Grab the slave cylinder & point the bleeder valve UP and the nose
( piston side) of the slave DOWN.

4) Bleed normally.... but do not keep the master resevoir full... keep it 1/2 to 3/4 full.
(NOTE the piston will move all the way FWD to the C clip.)

5)Re install the slave & linkage.. as you push the rod into the nose of the slave.. it will back fill the resevoir back up

6) Check pedal travel & grind factor...OK?

7)Top off rez, lube the shift linkage.

8) Enjoy the ride~



Vig!

 

[trackitman]

Thanks! Ken & Vig - I will try this after I pick up some fluid.

 

[larryfs]

get some real clutch fluid from GM #12345347 (?) not brake fluid

Larry

 

[BigRed]

Something I noticed while I was down there, if you ask me its very possible the fluid is leaking between the engine and the bellhousing.


What if the seals are blown in the slave cylinder? The fluid would travel down the slave into the rubber boot THEN into the housing where is would leak out the dust cover for the flywheel?

The only thing I can see interupting that from happening is the 1/2 groove in the slave cyln rubber boot.

Just a possibilty?

 

[89ZZ4]

When my slave went less than two months ago it DID leak into the bell housing area. When I replaced it the entire shaft and seal system was looking bad and corroded due to long term water in the fluid. It was the original 89 stuff which had never been changed out.

Phil (aka 89ZZ4)

 

[carguru]

Leaking clutch slave cylinder

When mine leaked, it leaked only into the bellhousing also. Symptoms were the clutch pedal going all the way down to the floor and empty reservoir. You will see oily stain coming from the bottom of the bellhousing and along the bottom of the tranny. Bleeding the slave cylinder and refilling the reservoir will solve the problem for a short term, but you will be doing the bleed/refill over and over again, each time a little sooner. Trust me, I went through the same thing for a little over a year before I changed out the clutch slave cylinder. Dealership that looked at it when it was under warranty misdiagnosed it as an intake oil leak the first time (car did not leak oil from the intake before, but certainly did after they fixed it), and a clutch master cylinder the second time. If you pull the slave cylinder off, the paint on the inside of the cylinder will likely show signs of fluid seepage (wetness and peeling paint).

 

[trackitman]

I removed the slave cylinder earlier in the week. It was definitely leaking into the bell housing. The oil was collecting inside the boot, then leaking through a very small air hole on the bottom of the boot.

I'll be replacing the slave here shortly. Couldn't find a rebuild kit, so I'm going new.

Thanks to all the replies!

Blaise

 

[trackitman]

Finished Replacement last week

Just wanted to give an update.

I replaced the slave with a new one last weekend. I didn't have an extra person to help with the bleeding process, so I invented my own based on ideas I've read in other posts and a little of my own creativity.

I found a container used in the medical community for suction/suction machines. It basically is used for suctioning fluids, while preventing the fluids from entering the main suction line. I was able to hook up my shop vac as the main line, and it did not cause excess suction because of the limitation of the size of the vacuum hoses I was using (plastic oxygen hoses).

First, I drained the master cylinder and the line without the slave attached. Then I hooked up the vacuum line to the end of the line where the slave attaches. Filled up the master cylinder with new fluid, and turned on the vacuum. While it was slowing suctioning the new fluid through the line, I pumped the clutch pedal with my hand while kneeling outside the car. I could see the air bubbles and new fluid exiting the end of the line into the vacuum line. I kept this up for a while, continuously running the vac, pouring new fluid in, watching it exit, pumping the pedal slowly. I was able to drain and replenish this part of the system in one step.

After this, I turned off the vacuum, but left the line attached so the fluid wouldn't drain out of the line going into the slave.

Next step was to separately fill the new slave with fluid before attaching to the master line. I used the suction method again, attaching the suction line to the slave bleed fitting, then attaching another line from the fluid container to the slave. Turned on the vacuum, and pre-filled the slave with fluid, making sure to rid most of the air in the slave. Closed the bleeder fitter, and capped off the other end.

Next step was to attach the slave to the main line. I removed the vacuum line off the master line and quickly attached the slave. Some fluid escaped from the master line, but not much. Once tightened, I reattached the vacuum line to the bleeder fitting, turned on the vac, filled the master cylinder, pumped the clutch pedal with my hand and removed what air remained in the system.

Final step was to attach the slave to the bell housing, two nuts and I was done. No leaks!

Drove it around the block a few times, smooth shifting.

Happy Thanksgiving!