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Sun Aug 24, 2008 9:53 am

Hi again volks folks! I have an 85 GL transporter w/43k orig and have a fluid leaking on the floor, and have noticed that I have to top my brake fluid res. off every once and a while. I think it is the brake m/c there is a box w/some curved or bent pipe and it drips rite on to the steering column boot at the bottom rite onto the floor matt, brake peadal still feels solid. Thanks for any help!! 8)

ironhorsejockey@hotmail.com

Sun Aug 24, 2008 9:55 am

Could be Clutch master. Easy to replace. Then bleed clutch

Sun Aug 24, 2008 10:40 am

When you replace the clutch master, don't forget to replace your carpets and check that the paint is OK on the drivers floor. Chances are, if the carpet is soaked, you will need to refinish that floor......sucks, I know. Been there.....

Sun Aug 24, 2008 12:18 pm

Also, don't forget the clutch slave cylinder may be about give up the ghost also. I've had to replace mine twice over the past several years.

Sun Aug 24, 2008 12:31 pm

It sounds like the clutch master. It is very easy to replace, bleeding the line is a bit tricky, but you can get that.

I wouldn't replace the slave (the one in the back) until it fails because it is such a pain to get to the bolts that hold it, also I ended up striping the bolt on it and it became a $500 mistake in the end.

Consider throwing a slave in the van so when or if it does break, the again who knows if it is newer than the master or not ?

The master is a cheap part your lucky, but your clutch will not work even if it is now, it won't soon. So don't drive or you will be stuck.

Sun Aug 24, 2008 12:43 pm

ps, if you change the master, don't let fluid get on the floor, and when bleeding the air out at the slave don't break off the nipple as I did, such a pain, then you have to change it. It is best to use a box wrench I think it it called that has the most sides to the bold instead of simple wrench, and put some liquid wrench or something like that 1st and clean any dirt rust off the nipple.

Sun Aug 24, 2008 1:45 pm

If you do the slave at the same time, you don't have to worry about breaking off the nipple

Or....

If you break the nipple, just pull out the slave you bought at the same time as you purchased the master and install.

:-)

Since you are under there, I vote do the slave at the same time and be worry free for years.

Sun Aug 24, 2008 4:27 pm

Most mechanics that I've talked to recommend that you change the slave at the same time. I've been told that the new better working master cylinder will often time blow out an old slave cylinder in a couple of hundred miles, and it is always to replace them as a pair. just my 2¢.

Sun Aug 24, 2008 5:16 pm

foodeater wrote: Most mechanics that I've talked to recommend that you change the slave at the same time. I've been told that the new better working master cylinder will often time blow out an old slave cylinder in a couple of hundred miles, and it is always to replace them as a pair. just my 2¢.

I don't see any truth to that. Pressure in the system is the same, a function of the clutch spring pressure and the multiplicative factor at the cross-shaft lever and pedal lever. The leverage (distance from lever point to centerline, or moment arm) at either position is fixed. Only the clutch pressure plate resistance is something that can be changed, but only by replacing the clutch (more pressure, perhaps) or by the pressure plate wearing out (less pressure due to spring fatigue and the springs being more relaxed as the disc thins). Anyway, the internal system pressure isn't altered by changing either hydraulic component.

Some have also said that both hydraulic bits should be changed at the same time because the range of movement in the slave will change and stir up debris deposits or cause the piston seal to ride on a non-worn portion of the bore. Also not true. The range of motion of the slave piston is just a function of the pressure plate's engagement location; this changes gradually as the disc becomes thinner, but isn't changed at once by putting in a new hydraulic cylinder at either end.

The one argument for changing both that has validity is the notion that it's easier to get them both while you have the system open and have to bleed it out anyway. That in itself, and the idea of replacing aged components as a general maintenance approach, is in my opinion, a good enough reason to do both in one job. But there's nothing about replacing one that necessitates replacing the other, from a functional perspective.

Sun Aug 24, 2008 7:14 pm

I'm with 10cent. There isn't any mechanical reason to change both. There is no circumstance where a new master or slave can cause the other to fail regardless of it's age. I usually only replace one. I also live in a dry climate where I haven't broken a bleeder in many years. I always use penetrating oil on them prior and use a t-bar with a 6-point socket to loosen, applying equal pressure to either side of the t-bar. Most often, breaking the bleeder is caused by using the wrong tools or wrong approach. Sometimes rust makes it so breaking the bleeder is inevitable (I grew up in Maine and know rust well).

As a side note, I would add that if the hydraulic system is not working properly and one questions whether the slave or the master has failed, the slave can only fail to leaking. If the slave is not leaking, the problem is the master.

Andrew

Sun Aug 24, 2008 7:19 pm

my slave went out about 10 days after the install of the new master.

Sun Aug 24, 2008 7:34 pm

Did you buy a lottery ticket that day?

Andrew

Mon Aug 25, 2008 12:28 pm

There is the possibility if you forward-bleed the system after replacing one component or the other that debris that is in the connecting line or in the reservoir can be carried forward to the slave and end up damaging its seal, causing it to leak and as Andrew said, fail, because a leak is failure with the slave. Since the systems usually never are bled proactively, only when there is a problem, bits of debris in the connecting line never go anywhere, just cycling back and forth, until the system is forward-bled and loose bits are carried to the slave, or stuff is loosened by the sudden high flow with the same result. The same could happen with dirt in the reservoir, but you're a fool if you install a new clutch or brake master without removing and thoroughly cleaning the reservoir; that's just begging for damage to your new parts. A thorough washout of the reservoir with hot soapy water, air dry, and washout with alcohol to remove every trace of water is routine when replacing any hydraulic master cylinder.

But the possibility of damage from stirring up the dirt in no way negates the comments I made above. There is no functonal reason why replacing one alters the operation of the other in a way that would hasten its demise. The damage in the scenarios above comes basically from sketchy work habits, and is completely preventable. In fact, replacing a slave alone and forward-bleeding without an open flush first could just as well damage the new slave as the old one, if there is plenty of dirt within the system to be stirred up. That might explain the numerous stories of people replacing the slave only to have the new one fail in a short time.

When the system is open, it ought to be open-flushed thoroughly with clean brake fluid to loosen and get out any debris inside the entire system. I know, I'm not perfect and don't always do it, too much in a hurry, but a thorough flush before installing clean new components greatly lowers the chances of a problem.