Hydraulic Clutch system


83westy

New member
Thanks Mike. I have never bled brakes or anything before. Is there a nice visual step by step guide in the Bentley? I have looked but can't seem to find it. Although I will admit I am still learning how to navigate the manual. Would I be better off to go ahead and replace the lines anyway as preventative maintenance? I assume if I bleed the lines then have to replace them, I just have to do it again.

The westy has 211k miles and the previous owner did not know when any type of clutch work was completed last.
 

Capt. Mike

Moderator
Yes, if you replace the flex line, especially the one at the slave cylinder that gets so much heat and abuse, you will have to rebleed. Bleeding the clutch is much like the brakes. Take off the dust cap (always use dust caps -- they are dirt cheap and prevent dirt and air from getting past the bleeder valve). Put a clear plastic tube on the end of the valve and direct it to a jar submerged in a tiny bit of brake fluid. Have someone pump the clutch while you open and close the valve. Once you get clear new fluid with no bubbles, you are finished. On the last pump, shut the valve in mid-stroke. The valves usually take an odd wrench -- 7, 9 or 11mm. The Bentley doesn't have detailed bleeding because it assumes the user has basic mechanical skills.
 

83westy

New member
I thought I had to use a Mighty Vac or something similar to bleed the clutch line from the previous posts I read. I bought one yesterday. Is the procedure different if I use the vac? Can I leave the valve open as I use the vac?

If I have a helper and open and close the valve as the clutch is pumped, I assume the valve should be opened as the clutch is depressed and closed before it is released, is that correct?

After inspecting the flexbile line near the slave cylinder I decided it should be replaced now. It it covered in crud and feels somewhat squishy. Is there a trick to changing this section that does not result in having to drain the entire line?
 
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Jason Rolfe

New member
Having problems understanding Bentley

Hi there,

I've got an '87 Weekender. Clutch slave cylinder just went out and I had it replaced.

I would have liked to have the Master replaced at the same time (as I hear it is a good idea to do that) but didn't quite have the money to do both and the master is doing fine.

Nonetheless, I'm hoping to get it done within the next month. I've been trying to read up on it in my Bentley to see if it is something I could do myself, but damned if I can't seem to find any info on replacing the Clutch Master in the book.

Any tips on using the Bentley? I've found that I can get info on some things and not others, and I wonder if I'm just not using it right (as silly as that sounds) or if I should try another manual. I feel like, for me at least, a good explanation on how to navigate the Bentley manual would really help me.

Thanks for any suggestions.

Jason
 

Capt. Mike

Moderator
The Bentley, being the official factory shop manual, assumes you have basic mechanic's skills, thus why there are sometimes just blow-up schematics with notes. There are two diagrams for the hydraulic clutch assembly -- 30.2 & 30.8 for the Syncro. Since they are the same, I prefer the clarity of 30.8. There are detailed instructions in this topic, post #5 on the first page!.

As an '87, you may find that the pipe fittings that plugs into the clutch master cylinder has been superceded by a 12mm banjo bolt. That's an improvement, but you will need two new 12mm copper seals and torque to 18 ft-lb. Ditto the gravity feed tube from the brake master cylinder reservoir. They share the hydrualic fluid supply.

I do not find any direct correlation between wear or failure of the clutch slave and master cylinders. I replaced my master at 139k in 2001 and the slave is still original and going strong, now 175k. Since the master is such a pain to change, I wouldn't replace it if there is no problem. (Personal Opinion!!)
 
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Jason Rolfe

New member
Thanks Capt. Mike.

I kind of assumed that was the deal with the Bentley. It came with the van and has been really useful for some things. I can do fine mechanically as long as I have pretty detailed directions, so sometimes I have to look to other places for that detail.

Anyway, I appreciate the help. I'm new to the site, and looking forward to really combing through it all.

Jason
 

humachines

New member
I have an '89 Westfalia Syncro with absolutely no pressure in the clutch.

Background: I bled the clutch about six months ago after weeks of the clutch losing pressure, and finally, difficulty in shifting. This time it was overnight. Full pressure to no pressure. I could not see any leakage, and the reservoir slightly less than full (maybe slightly more than normal usage over six months for this van).

I tried to bleed it again, and despite the most vigorous pumping and holding on the part of my friend, each time I opened the bleeder valve, fluid barely dribbled out. Last time it spurted out with gusto. Also, the fluid was fairly clean, not dirty or bubbly like last time.

Possibly complicating factor: I removed and replaced the water pump and because of various factors it took about a week and a half. I can't imagine how this could affect the clutch pressure, but the clutch was working perfectly when I drove it into the carport and had zero pressure when I started it up after the water pump replacement.

Is there any sign or degradation of performance prior to the slave or master cylinder going out? Are there any other reasons it would go out literally while just sitting there in my carport. Any diagnostics I can do? Would it help to bleed it with a proper bleeder pump before doing anything else? Stumped.
 

scotsborn

New member
If you've been gradually loosing pressure over some months then we have an issue. A little background if I may: the master cylinder supplies the pressure, the fluid transfers the pressure and the slave moves the clutch fork to actuate the clutch.

So, if the master is good then the pressure it develops should be going somewhere. If the slave was worn then the fluid would leak past and you would see a leak. The fact that you have no leaks (you didn't mention any) would suggest the master cylinder is the issue. There is a mechanical linkage between the clutch pedal and the master so check that. I would be surprised if it was defective since it would probably make noise when it failed.The master also gets fed from the brake reservoir and I believe the clutch port is above the brake ports so that the clutch goes before you loose the brakes. Check the level in the reservoir. If all these do not indicate an issue then try opening the fitting right at the end of the master and see how much fluid comes out. If it is low pressure then the master cylinder would be the culprit.

Let us know what your issue was / is?
 

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