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MG MGB Technical - Urgent clucth-related help needed for 1967 B!

Please help - almost comic situation requires resolution ASAP...

I'm borrowing my brother's '67 MGB GT (with permission!). It's lovely. I like it. He loves it more than life itself. He calls it Phoebe.

He's on his honeymoon. He's back tomorrow. Phoebe is very ill indeed. Sh*t.

The problem is the clutch. The pedal goes pretty much all the way to the floor and does nothing. This makes changing gear a painful and noisy experience, so I had it put on a flatbed yesterday and taken "home".

I've done the following to try and rectify the problem:

1. Ensured the master cylinder was full of fluid.
2. Topped it up when it was only half full!
3. Bled the system, which required serious elbow grease in loosening the bleed nipple, but bled it we did. No air inside, so I finished the job and tried the clutch again.

Didn't work.

There are no leaks that I can see, but something is clearly wrong. My money's on the slave cylinder, but that's just me guessing.

Any thoughts?

Cheers,
Nick
Nick

Clutches go, bad luck. Best thing is to see how far the release arm moves when you press the pedal. If it does not move, its the slave/master or clevis pin, these can wear. if it moves an inch or so, then its the clutch.
Tatty

If the release arm does not move correctly it is most likely the master cylinder.
The slave cylinder can only be a problem if the fluid gets past the seal, in which case several operations will empty the master cylinder reservoir.
When it is said that the release lever does not move correctly it should be defined which way.
If you have an internal clutch problem the release arm will not return fully, but in that case the slave pushrod also does not return and on the next operation you do not have a "pedal to the floor".
If the master cylinder piston does not return correctly you get a "pedal to the floor"
The cause is usually a broken spring inside the master cylinder. This is often caused by a broken, or missing, pedal lever return spring. The master cylnder interal spring is overloaded if it also has to return the pedal lever.

Mick
M F Anderson

Feel up at the top of the clutch pedal - if there is fluid up there, it is the master cylinder leaking - half a tank of fluid must have gone somewhere!
Chris Betson

I'm with Chris. Hydraulic fluid doesn't just disappear (without leaving a trail).

My best bet is that it's the master cylinder. Run your hand up along the clutch pedal arm to check it for
leaking fluid dribbling down it's length. Nothing? Remove the pedal box cover and check the area
around the pedal pushrod and rubber boot for dampness.

Then, I'd turn my attention to the slave cylinder and hose. Jack up the car and look for drops of fluid
or dampness on either part. If not immediately obvious, then wipe everything clean. Next, press & hold the clutch pedal a few times. Check the rubber boot on the slave cyl for wetness. Run your hand
along the rubber flex hose, especially where it joins into the metal threaded fittings. Still nothing?
Try leaving a sheet of newsprint under the car for 24 hours. Check for wet spots on the paper on
the next day.

Fortunately, renewing the seals on the clutch system is not too difficult - but completely bleeding all
air bubbles out of the works can sometimes cause much grief. Check the archives for this as much
has been written on this subject, and many home cures abound.

The flex hose can present a challenge. It's easier to disconnect the batteries and remove the starter
in order to gain better access. It also helps to have a set of "crowsfoot" flare wrenches for this.

My advice: After looking things over - leave it alone. Report everything to your brother.

As it's owner, he's probably more familiar with his car's history and medical needs - and he no doubt
knows well that the hydraulics on these cars can go south on occasion as part of normal wear. Also,
he can probably arrainge to set things right more efficiently and without too much guesswork or
collateral damage (to car and/or wallet).
Daniel Wong

This thread was discussed on 07/07/2003

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