Hydraulic Clutch system


diana

New member
Topic created to separate hydraulic clutch system from mechanical clutch problems. Clutch master to slave cylinder questions only; mechanical problems inside bell housing remain in "Clutch problems" topic. Pedal system questions remain in their own forum.
 

A. Cooper

New member
Transferred for clarity in new topic.

diana Junior Member posted January 11, 2003 10:58 PM

I NEED SOMEBODY TO TELL ME WHY THE BREAK FLUID LEAKS WHEN IT GETS REALLY COLD. I LIVE IN NORTHERN MN. I FIND FLUID ON THE DRIVER SIDE FLOOR MAT EVERY SPRING!!!! SOOOO ANYBOBY-HELP You don't say what year your van is, so it is difficult to help you (please see the Site Guidelines at the bottom of this page).

Cooper's response: Assuming you have a Vanagon, your leak is possibly coming from your brake master cylinder which, along with the brake-fluid reservoir, is tucked away inside your instrument cluster. If you have a manual transmission, you also have a clutch master cylinder mounted just above the base of your steering column and actuated by your clutch pedal. Both master cylinders share the same fluid reservoir.

Either one of these -- or even the reservoir iteself -- can leak and drip fluid onto the floor near the pedals. You'll need to trace the drip back to its source to know which is leaking, then rebuild or replace the defective component. Such a leak may be temperature-related due to the fact that the metal parts and rubber O-rings and seals all expand and contract at different rates, so their ability to seal properly will vary with temperature.

In any case, it tells you something is about to go. When you determine what it is, read the appropriate archives here in the forum and check your Bentley manual for the proper procedures for repair.

Good luck!
 
Last edited by a moderator:

Mike Robinson

New member
Been there had that.

For me it was a clutch master cylinder leaking.

Solution: replace cylinder.

You can check your reservoir level - remove the instrument cluster cover and see how much it leaks.

I am not sure how it can be temp related. My leak was use related - press on the clutch and the leak increased - although it did drip all the time.

Regards

Mike
 

Capt. Mike

Moderator
Transferred from other posts to create new topic.

Capt. Mike 7/5/01 -- Responding to a clutch life question: The '85 has a hydraulic clutch, so should go 100,000 miles or better with proper driving techniques. What is your mileage on the clutch?

Clutch failure generally falls into two categories -- slippage or worn linings. With a hydraulic clutch, there is also the possiblity of a hydraulic system deficiency.

The clutch slave cylinder is easily visable in the LR engine compartment. Examine it for leakage and smooth 'throw'. Also check the amount of actuating rod visible. Unfortunately VW doesn't mark or otherwise spec that throw, but as the clutch adjusts for wear, the rod length will increase. If the rod has a lot of 'throw', the clutch may be worn.

Capt. Mike, September 21, 2001 -- Responding to a question on clutch shudder: About the only thing that could give you some clutch shudder at start that wouldn't be inside the flywheel housing would be a hydraulic problem where you either have air in the system; or a bad master clutch or slave cylinder. Bleeding is simple and like brakes except you half to catch the pump in mid-stroke since you can't do the 'pump & hold' method like brakes. In the US, you can get rebuild kits for the slave cylinder but not the clutch master cylinder.

Capt. Mike Tech Writer posted November 18, 2001 02:52 PM

Replacing clutch master cylinder, Vanagon

This weekend I had the unenviable task of replacing the clutch master cylinder on my '90 4WD. Diabolic revenge by the Kaiser for losing WW I! How did I know it was leaking? It was dripping on my foot and the steering column. I prayed it wasn't the brake master cylinder, which is even worse!

I haven't figured out the difference between the Bentley diagrams 30.2 for the 091-092/1 & 094 transmissions and the 30.8 diagram for the Syncro, except some notes, so probably worth reading up on both before tackling this job.

First warning: brake fluid will destroy paint. Have your carpet laid back & covered; all paint-work protected and tons of absorbing paper towels underneath the work area. You will need mirrors and auxiliary light -- I'd suggest the flexible wand lights in various tool catalogs. You will have to remove the instrument cluster cover for access to the reservoir and the steering column cover for working room & visibility.

The clutch master cylinder feeds from the brake master cylinder reservoir. That's a braided-cover hose attached to the clutch master cylinder in the middle of the forward facing surface. After syphoning as much of the reservoir as possible, I'd suggest pumping the remaining fluid through the clutch slave cylinder bleeder. The hose is a push on fit and can be worked off, but there will always be some fluid to drip -- thus the caveat about paint damage.

The pressure line is a flare nut fitting through '87 and changes to a banjo bolt afterwards. Remove the fitting from the lower after-facing fitting. If a banjo bolt, have two NEW 12mm copper seal washers at the ready. I'd suggest you stick with VW OE because the outside diameter must be correct to fit into the recess on the cylinder.

Remove the two 8mm bolts holding the cylinder in place. The pedal pushrod will slide out of the boot. If you have a leaker, the boot is probably full of fluid -- more care against spills.

I have not been able to find any clutch master cylinder repair kits, thus assume you will be putting a new cylinder in. The new cylinder should come with plugs on the in & out ports, plus a plug in the top of the boot.

Remove the plug in the top of the boot and feed the pedal pushrod in as you raise the cylinder into position. Insert & tighten the two 8mm bolts to specs (18 ft-lb.).

Remove the in port cap and attach the reservoir feed line.

Remove the out port plug and attach the line to the slave cylinder. If a banjo plug, use new seal washers. VW does not give specs on the banjo plug so I used the 18 ft-lb. called for in another manual. If a flare nut, I'd stick with the 11-14 ft-lb. of a brake line fitting.

Now the real thrill -- bleeding the clutch system! When doing a fluid change, it's never been a problem because the system wasn't full of air -- I just pump fluid through until I get plenty of clear new and then shut off the bleeder in mid-stroke. Not so when full of air.

Apparently, the pedal will just compress & expand the air bubbles in the line so fluid flow is negligible. I finally attached a vacuum pump (one of the little Mighty Vac brake bleeder kits in the blister pack at the discount auto parts place is fine) and sucked fluid through until most of the air had been purged.

Since you have emptied the reservoir, it's a good time to change fluid in all of the brake lines as well. You have probably gotten some air in them anyway.

After that was done, I took it for a test drive and the clutch was lousy, catching near the floor and not shifting smoothly -- indications of not fully disengaging. I suspected more air.

Sure enough, the 2nd bleeding got a big shot of foamy, air-laden fluid. The test drive had driven the remaining air back to the slave cylinder. By the time I pumped that through until getting fresh clear fluid, I had good clutch feel and the proper engagement point.

Fluid use was a full quart with brake fluid change. (Stay with DoT 4 specs!) Brake fluid is poisonous so don't try any jury-rig suction gizmo -- stick with the Mighty Vac or better. Once you are into regular bleeding, a hose and small jar are adequate.

Replacing/Rebuilding slave cylinder

roquibello Junior Member # 1965 posted 01-20-2002 03:16 PM

Greetings from Mexico City

I'm on a cross country journey in my 1985 Westy, hoping to get as far south as Costa Rica.

Right now I'm broken down in Mexico City with a leaking slave cylinder. A friend from California will mail me a spare slave cylinder. Can someone coach me through replacing/rebuilding the slave cylinder?
Also, is DOT 4 brake fluid imperative, or is DOT 2 or 3 OK?

I appreciate your help.
Blessings from Cem-Anahuac,
Roqui

Capt. Mike Tech Writer posted January 22, 2002 12:20 AM

The clutch slave cylinder is a fairly straightforward replacement. It has a metal flare fitting at the cylinder, so you may find it easier to release the clip holding the flexible hose so there is a little play when removing. The layout is fairly well shown in the Bentley, pages 30.2 & 30.8. Although 30.8 is for the Syncro, the layout is similar. Check the pipe carefully, they can crack if stressed, typically inside the flare nut at the flare itself.

[Later models, >mid '87, have banjo bolt fittings instead of the flare. An '85 wouldn't unless upgraded along the way. If so, replace the copper seal washers.]

On the road, I'd recommend a replacement. Rebuild kits are available, but the extra tools, shop cleanliness & special chemicals required, mean it's not usually an on-the-road repair. There are no real tricks although access will be fun because you'll have to work mostly from inside the engine compartment.

After the hydraulic line is disconnected, two bolts hold the cylinder in. When installing the new, be sure the rod is properly lined up with the clutch lever. The new cylinder will 'self adjust' when bled.

Bleeding is tricky. Since you can access the site from the road, look at the comments above about clutch master cylinder replacement. A pressure bleeder isn't necessary but you may have to have a vacuum bleeder/pump like the little Mighty Mite to pull fluid through. Otherwise pumping the pedal during manual bleeding just compresses and expands existing air pockets. You will probably have to manually bleed a couple of times after some driving. If the clutch engages too close to the floor or you have clash, it's not yet bled thoroughly. If nothing is available, don't try to siphon or blow by mouth -- it's highly poisonous. You might be able to jury-rig a pressure devise with a bicycle pump or something.

If DoT 4 isn't available, DoT 3 fluid is acceptable but remember the higher likelihood of fade if in extremely high temperatures or heavy use such as mountain driving where brake fade may be expected. DoT 2 is unacceptable for what is basically a 2½ T truck system.

Hope this helps.

Hard getting into gear

Oz Todd Member posted August 04, 2002 10:39 AM

I had the clutch slave cylinder replaced yesterday and now I find it really hard to get into gears, and it feels as though im lacking pressure in the clutch. The van runs fine, its not slipping once it is in gear, and gives no hint of problem with the gears themselves.
Is it possible that this is due to some shoddy work in replacing the clutch slave cylinder or could it be leading on to another problem?

magowanc Member posted August 04, 2002 06:37 PM

The clutch system works similar to the brake system. First check to see that you have enough brake fluid. As the clutch system draws near the top of the resevoir, the brake fluid resevoir should be at the max line. Also, the clutch system needs to be bled, just like the brake system. Air bubbles in the clutch system would create the symptoms that you are describing. If there is air in the line, this definately indicates shoddy work.

Corey
'85 VanagonGL Westy
1.9L Wasserboxer
 
Last edited:

tyler

New member
I have a 88 vanagon and having a few problems with the clutch. I recenctly tryed bleeding the clucth bleeding screw and filled the brake/clutch resorior with dot 3 fluid. It drained fine and i dont think there is any air in tne line. Also after starting, it would not go into gear. I then started it in first and released the clutch slowly and the van did not move. Then i realized that the clutch was stuck i could not push down on the pedal.

thank,

gta
 

Capt. Mike

Moderator
First, you should be using DoT 4 fluid; DoT 3 is pretty much out the window as the econo-fluid from the 7-11's; the weight and resultant heavy use of brakes calls for DoT 4.

Second, you don't 'drain' the hydraulic clutch system. You have to bleed it via the process described in the topics elsewhere on the site per the posts above (Guideline #4).

Watch the clutch slave cylinder and see if it is moving its full range when someone else presses the clutch. If not, you may have a blown clutch master or slave cylinder. The fact that fluid flows through doesn't mean one or the other isn't leaking internally around their seals.

If it is moving full range, then the locked clutch is a mechanical problem which has its own topic.
 

jerepowers

New member
Just replaced the clutch master cylinder on my 1984 Westy as a part of a complete vehicle-wide replacement of the hydraulic system. (That included the clutch master cylinder, brake master cylinder, both calipers, both wheel cylinders and all four flex hoses; slave cylinder was relaced last year and is what got me thinkig about replacing it all. All but one caliper showed some minute sign of leakage.)

The clutch master cylinder was the most difficult part of the whole process, mostly because of a lack of sight and lack of room. Mirrors and lights did me no good.

A couple of tips:
First, read Capt. Mike's clutch master cylinder replacement post. There is nothing in the Bentley on this operation.

Jack up the car a few inches and put it on jack stands. Doing this job requires leaning in from outside and it's too tall to do on your knees and too low to do standing up. By jacking it up a few inches, you can work on your feet. (Or at least foot, as you lean in.)

Getting the linkage rod from the clutch pedal into the rubber boot is surprisingly difficult. I found by pressing the clutch pedal almost to the floor brought the tip of the linkage (which must go through the hole on the boot) down to a level I could deal with best. Pressing the pedal is easy because there is just one spring offering any reistance. However, once you have the rod in the boot, you have to raise the master cylinder as you release the clutch pedal, otherwise it slips out. I found that reaching around and holding the master cylinder from the brake pedal side worked best.

The steering linkage is right by the area you have to work and gets in the way. But there is a crank-like offset in the linkage there. Move the steering wheel so that the offset is toward the rear of the vehicle. This give you the most work space right where you need it.

When bleeding, you have to use a vacuum, as Capt. Mike says. But make sure you depress the clutch pedal partially to allow the fluid past the master cycliner piston.

Finally, I learned from Capt. Mike and the second bleeding. I just stayed in my drive way, pumped the clutch about 40 times, let it sit for a while and the bled it again.
 

guest

New member
On my 1985 Vanagon, I noticed a bit of clutch pedal "slop" in the 1st half inch of travel, before I could feel the hydraulics engage. The pedal was just resting "up" on the spring.

I initially guessed that the clevis pin (and/or its hole in the pedal arm) was worn, giving me the slop. After I got my fingers in there, I figured out that it was probably not the pin causing the issue, but the shaft was mis-adjusted. Right above the rubber boot over the master cylinder, there is a lock nut, and Bentley seems to show that if you take out the clevis pin, you can rotate the shaft and extend or contract it to the proper length.

As I was feeling around back there to check all this, my 20 year old rubber boot over the top of the master cylinder disintegrated at creases of the "folding bellows". I tried to goop some polyurethane sealer over it, and some duct tape (ugly, I know) but it's such a nasty tight spot in that area that I could not seal all the cracks in the boot. I might have even got some "goop" on the shaft itself, inside the broken boot. What a mess.

My master cylinder seems ok for now, and I don't want to pull the dashboard to change out the clevis pin yet, since it seems just to be a problem with shaft adjustment, not a worn pin & pedal arm.

Really, I just want to leave well enough alone until I really am forced to replace either the master cylinder or the clevis pin... hopefully many thousands of miles from now!

My question is, how bad for the master cylinder is it to have the rubber boot broken? This isn't like a CV joint, under the car in a constant bath of grit. I'm hoping the damage to the rubber boot is unlikely to be a big deal, but since I've never pulled the MC and looked down under the rubber boot, I don't know how it's constructed and whether I'm soon in for trouble with the cracks in the bellows.

Please advise!
 

Capt. Mike

Moderator
With the boot off, you are looking directly at the piston cup -- the part that goes in & out with the brake pedal. Without the boot, it will eventually pick up dirt and leave the cylinder exposed for scratching & damage. Then leaks go direct to the carpeting and paint damage.

What I suspect is not that you actually had a problem with the push rod adjustment, clevis or pin -- these rarely change in use -- but you have picked up some air in the system or are getting some leak-by with the piston seal. This is what takes the extra pedal movement to 'use up' until the hydraulics are pushing the slave cylinder. Thus you have compensated for one problem by introducing another, one that may have your clutch not fully engaging. Remember, there is SUPPOSED to be 0.5 mm play in the push rod anyway, which would translate to ½" at the pedal.

As a temporary boot fix, do not use duct tape or a sealer -- they can dissolve from brake fluid, heat & age to gum up the whole works. Hit the discount auto parts stores where they have the blister packs of common repair parts and look for a boot that is similar -- probably a shock tower boot. Slit it vertically and the using a plastic wire tie, secure it to the push rod shaft so that it acts like an umbrella over the master cylinder piston. You may have to shorten it. Place it such that it doesn't interfere with the piston, but it should keep debris out until you are ready to tackle the replacement. From your symptoms, that may not be very far away.
 

Zonetrap

New member
I have a 82 Diesel Westy. Just replaced the starter last night, fired up beautifully, but trying to get the van in gear was a real problem. The clutch goes all the way to the floor and its tough shifting.

Ive read this topic, just wondering what people think? Fluid leak?
 

Capt. Mike

Moderator
The starter & clutch have no relationship so replacing one shouldn't affect the other. But . . . you were working in the same general vicinity and the hydraulic lines of the clutch are the most fragile part that could have been inadvertently affected. Thus, yes, it is possible you've caused a leak which could introduce air. Once air is in a hydraulic clutch, the pedal moves easily (compressing air) instead of moving the slave cylinder. However, this is easy enough to check by watching the master cylinder arm -- is it moving appropriately through it's full range? Usually an unbled master cylinder also causes clashing, not just hard shifting. If contact with the hose at the salve cylinder has created a leak, the hose has probably become brittle or damaged and should be replaced.

Hard movement of the shift linkage would be discussed in the SHIFT ROD . . . forum.
 

Capt. Mike

Moderator
Transferred to consolidate same topic.

icebox500 Junior Member posted April 20, 2005 04:40 PM

I recently had my clutch replaced. Since getting it back, it has been harder to shift, quite difficult getting it into third. By hard I mean it needs more time to synchronize. It feels like the clutch is not going all the way in.

I had problems that led up to replacement. I have a question about the clutch pedal assembly in regards to this. I was fiddling with the master cylinder when I noticed that the rod pushing into it is curved/bent. Should this be the case? I also felt an adjusting nut (so it seems) up there.

Q: How the heck to I remove the assembly to examine it? I don't have a manual right now or I'd take a look

Any and all help appreciated.

James
'89 Westfalia

Goldibox Power Member posted April 20, 2005 06:32 PM

Getting to the clutch linkage adjustment requires removing the pedal assembly, which means the dash needs to come out. A couple of shortcuts - leave the hydraulic lines connected to the master cylinder - there is enough play in them to get the pedal assembly out. Also, you need to remove the clutch pedal before the assembly will come out from behind the firewall.

Once you get the clutch pedal out, look carefully at the hole for the pivot pin, it will probably be elongated. I repaired mine by drilling it out and installing an oil-less bushing cut to length to fit inside the clevis arm. You can also weld up the hole and drill a new one. The pivot pin will also be worn and should be replaced. I ended up using a shouldered bolt and a nylock nut instead of the pin and c-clips like the stock setup. The clevis itself will probably not be worn.

Once you fix the slop in the clevis connection, you should be able to re-install it without adjusting the shaft length.

Good luck,

Tim

TJ Hannink
Goldibox - 1987 Vanagon Camper, Wolfsburg Edition
1981 Bluebird Wanderlodge, FC-33
Winter Park, Florida
 

montot

New member
hello all the romantics out there!
icon_smile.gif

and,
Oh captain, my captain!

I have an 85 westie with 110000k on its second engine. right after a loaded (we were 6 on board+a little stock) trip up nasty logging roads my ever so supple clutch lost some of its youth. It became increasingly difficult to shift into gear over the course of a week or two. the problem seems to be that the clutch does not allways fully disengage transmission. through a little trial and error I discovered that when at a full stop and unable to shift into 1st I could still shift into fourth -sometimes with some labour- and then this "unlocks" the gearbox so that I can shift into 1st. Other times I get the gear in with a strong kick of the wheels. The problem is most prominent when the clutch is cold, that is when the engine is cold OR after long highway runs where I dont shift often. sometimes I get a little chatter too.

so I finally came up with a method that seems to work fine: I pay special attention to make the clutch slip a little whenever I shift, specially in 1st & 2nd. gears, which warms it up enough to get it to act quite normally. I don^t mean long reving slips, just more than I normally do, which is the bare minimum. As long as I use this technique everything runs fine (except when starting cold) and as soon as I miss my slips for a while shifting gets hard (even harder when cold).
Here^s when I must note that I have no involuntary clutch slipping at all, which makes me assume that it must still be in good -or acceptable- shape.

I had thought I might solve the problem by getting to the master cylinder nut and screwing the rod out a little. This was the first question I wanted to put forward.
after reading the posts here I found out about the possibility of air in the system. I have not bled the hydraulic sistem yet for I am reading about that right now and my van is at a garage getting a new paint job nor have I checked the fluid level. but I have a question for when I do so: how excactly is the bleeding process done when you do not have a vacuum pump at hand? from what I gather in the topic that seems to be described in guideline#4 but I am not sure what guideline #4 means, or where to find it... I even made a search on the site (for guideline, guidelines, guideline #4) and no results pointed
elsewhere than the topic itself, which I have read.

Resuming: I am assuming that the heavy use during the trip wore out the clutch, thus increasing the travel necesary for correct clutch action. It works quite nicely when warm (not HOT), fails to clutch when cold. thus I assume it just needs a little more "push", or travel. my lines might have picked up air from adjusting conditions on the fluid reservoir. will bleed. if NOT, should I check/adjust the push rod? or am I just not wanting to look at a clutch repacement?

thanks, love you for you too love westies!
they're so
soo
sooo
nice...
arent'they?

cheers,
.monte
 

Capt. Mike

Moderator
At the bottom of EVERY index & topic page is a link to the Guidelines. #4 refers to reading ALL the message boards & forums rather than reposting something that is already there. We also expect members to use the FIND feature. This saves bandwidth, expense and making the boards easier to navigate. Checking the fluid level should have been done before posting, Guideline #3.

My first reaction is go buy the vacuum bleeder kit; I see them below $39 and should be in every home mechanic's tool box since they can be used for many other vacuum & test functions. You don't need the exotic ones like Snap-On; the plastic MightyVac is fine. Bleeding is described in the Jan 22, 2003 post. However, since your are not totally airbound, the pump shouldn't be necessary. Do a 'fluid change' by pumping through until you get new, clear fluid from the reservoir.

Your symptoms do sound like air -- it's reaction will vary with temperature. Do NOT attempt to adjust the master cylinder rod for wear -- that is handled automatically by the slave cylinder. Your work-arounds are just wearing out the clutch and can damage the transmission.

How old is the clutch? Hydraulics go much longer than the old mechanical clutchs, but they still have a limit. I'd consider wear-out possible if over 100k -- or at least that it's probably worn enough for replacement if the engine or tranny is out for any reason.

Start with the basics. First check your transmission for proper fluid type & level. Then bleed the clutch, preferably with a fluid change in case there is moisture in the hygroscopic fluid. That should be done every 2 years anyway. Also check your clutch pedal linkage for pivot wear and bushing damage. Also check your shift linkage. Worn or out-of-adjustment can make shifting difficult and be inconsistent. Shift linkages have their own forum.
 

montot

New member
Yes, I finally found the guidelines.. sometimes my own nose covers up some of my visual field.. sorry about that.

So I'll follow up on the subject as soon as I can get my hands on my van.
thanx!
monte
 

montot

New member
I have one further question regrding the bleeding of the clutch:
Is the bleeder equipped with a ball valve, so that I can leave it open while I pump the clutch and add fluid or should I have somone pumping the clutch while I am at the bleeder opening and closing it at every stroke to keep air from getting into the system between strokes?
thanks,
.monte
 

Capt. Mike

Moderator
Sounds like my problem -- blessed with Mom's family's Norwegian nose and now of the age my arms are too short to reach the computer without bifocals, which means I'm looking down through the bottom of the glasses to see the computer screen.

The bleeder is identical to a brake bleeder, a tapered seat screw with vent. Since you don't have the 'stop' of brakes, it is necessary to have one open & close the valve while another works the clutch pedal. The ideal situation -- and necessary at least at the very end -- is for the person at the slave to open the bleeder as the operator pushes the pedal and then to close the bleeder before the pedal reaches bottom, i.e. mid-stroke. Unlike a brake, the slave can refill with air during the release stroke and defeat the pressure stroke results. Like brakes, have a hose lead to a jar with a small amount of brake fluid in it. I prefer glass so I can see the bubbles as the hose and then clutch line is cleared of air. It easier to reach through the engine hatch in the cargo area instead of from underneath.
 

montot

New member
OK, thanks for your answers. I bled the clutch manually, a friend pumping and me at the bleeder opening and closing at every stoke. went through DOT4 fluid untill it started coming out clean. the clutch started working correctly afterwards. even in the cold. After a few days/kilometers -temperature lowering due to the oncoming winter-, the problem has somewhat come back, but I believe a second bleeding will do the job.
cheers!
.m
 

Capt. Mike

Moderator
It may eventually take a 3rd because moving air to the end of the pipeline takes time. If the 2nd & 3rd bleeding don't solve it, or if it keeps returning after a while, it could mean you have an air leak feeding the master clutch cylinder (at the pedal). It could be sucking air in the feeder from the brake cylinder reservoir, or an air leak in the master cylinder itself. An air leak in the slave would be my last guess. It gets the most abuse in terms of dirty exposure on the rod, but it also is on the end of the pressure stroke, so is further from the feed sources.
 

Top