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MG MGF Technical - Clutch Pressure
Slight cock-up bleeding the clutch over the weekend, in that we pumped a couple of times (as per brakes), without shutting off the bleed nipple.
I've since not been able to get any pressure back in the system, or for the pedal to return, although I am slowly getting air out by following the manuel procedure (inc manually moving the clutch arm).
I spent a long time bleeding for very little effect, so is it just a case of sticking at the bleed procedure, or does it sound as if I've damaged either master or slave cylinders?
|Russ D Mellor|
|No sure Russ, but I do worry that if pressure is failing to return then something is amiss in the master cylinder (I've done something very similar to a brake master cylinder on the MG ZT in the past :o( )|
Cheers for the advice, after another unsucessful bleeding session yesterday I suspected something similar. Although I have a friend borrowing a suction bleed tool whose confident it's just an airlock.
So we'll try that before I worry about replacing any parts, wish me luck!
|Russ D Mellor|
(What a great isle you live on. I still enjoy watching the Isle of Wright festival held there in 1972...)
I assume that you had only tried to bleed the slave and have not touched the master?
You first need to bleed the master. I am not sure of the procedure you have used thus far, so I will exlain it for you and maybe others may benefit from it....
At the master:
1. remove the spare wheel and the black plastic shroud that covers the master.
2. from inside the car, tie a rope around the clutch pedal so that you can pull it up when it is depressed.
3. add brake fluid to the master clutch reservoir so that it is full to the top.
4. place rags all around the master and on the neck.
5. loosen the master top connector and then get someone to depress the clutch pedal quickly. get them to hold it in until you tighten the connector.
6. Pull the clutch pedal up using th rope.
7. loosen the top connector again and depress the clutch pedal. tighten connector and then pull up the pedal. Do this until the fluid coming out from the top connector has no bubbles and no foam.
8. when finished then again check/fill reservoir.
At the slave:
1. access the slave by removing the back shelf carpet, engine cover etc.
2. place a ring spanner over the bleed nipple and then place a clear long tube over the bleed nipple. run this tube down to under the car where you will have a jar to collect the bleed out fluid.
3.loosen the nipple a little. then depress the pedal quickly.
4. tighten the nipple and then pull up the pedal.
5. repeat this precedure until the fluid coming out from the nipple has no air bubbles. keep checking that the reservoir has fluid.
6. finally lift the pedal and depress as normal. there should now be pressure and the clutch lever should move when pedal is depressed.
Hope this helps.
|Hi Branko, |
Many thanks for your comments, and the Island is indeed a fab place to live and well suited to an MGF, providing your ride height and suspension are ok! We originally chose the F over an MX5 as it was so much more comfortable on the rubbish Island roads, and I've hardly regretted the decision since.
I have the RAVE CD so pretty much followed this procedure exactly, including bleeding from the master top connector.
Where I went wrong is initially treating the clutch bleed like brakes, from the slave I had my pipe and jar, loosened the bleed and had the girlfriend pump the pedal with the bleed open. Air and fluid came out, but after a few pumps the pedal just stayed on the floor. I've followed the correct procedure for hours since then (this is not a figure of speech), and suspect I have an airlock somewhere in the long pipe between master and slave. Further research kinda bears this out, so I'm going to try a gunson Eazibleed, as per my other thread.
The clutch operated ok before, so I have no reason to suspect faulty components.
A benefit is that I've managed to pump through and replace most of the old fluid, which was old and discoloured, but has become one of those jobs you kinda wish you never started!
|Hopefully the Easibleed will help, but it's not all it's cracked up to be. I would use an assistant in preference to an Easibleed.. it's really only any good if you cannot persuade your girlfriend/wife (or both!) to help.|
There's an MGB trick whereby you reverse bleed the clutch from one of the brakes - I've not done it myself but you could find out more in the archives.
|I picked up the Eazibleed & if it does what it says on the tin, it just might work. It has a cap that replaces the master cylinder cap, a resevoir and uses pressure from the spare tyre to blow through old fluid & air. So hopefully will clear any air lock and repressurise the system.|
I'm surprised this is not a more commom problem of the F, makes me feel somewhat stupid for messing it up in the 1st place!
from your initial description I would say that a little air may have been sucked in at the slave end and that should not be so difficult to expel. There is no way for air to enter from the master end since it only sucks in fluid from the reservoir and then pushes it down the pipe to the slave. (unless you had opened the top joint at the master, at some stage and allowed air to enter).
Disconnect the slave push rod from the clutch lever and test that it indeed squits out air and fluid by pushing the rod by hand. If it shows no signs of doing that, then you may need to remove the slave, dismantle it and see if the seal is still intact and working. I've rebuilt many slaves and have always replaced the seal for a cost of a few dollars. I source the seal from a brake place that has replacements.
|All sorted with the Eazibleed, see other thread etc...|
This thread was discussed between 11/05/2009 and 17/05/2009
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