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MG Midget and Sprite Technical - Bleedin' clutch
Having replaced my leaking clutch slave cylinder I'm experiencing a particularly bad case of clutch bleed fail.
I've attempted to bleed the system twice - Saturday and yesterday - about 45mins each time using the eezibleed at about 20psi, with clean fluid coming through and no bubbles. But absolutely no clutch. Pedal goes to the floor. I can't imagine where the air is trapped! I've tried lifting the front of the car as high as I can on a trolley jack, likewise the rear. I'm not a virgin - I've bled the on two previous occasions. First time was a bit of a pain but gave it up eventually, second time a complete dream - went easy. Don't know what I've done differently this time!
So, what are everyone's top tips for dealing with a troublesome clutch bleed.
Finally, i remember some discussion of a remote bleeder - would the inventor of that bright idea be kind enough to share it with me? is it as simple as moving the bleed nipple higher than the M/C?
|The remote bleeder is simply an idea to help with opening the bleed screw so I don't think that helps.|
Each time I bleed a clutch I ALWAYS push the slave cylinder piston all the way into the cylinder whilst bleeding this ensures that air can not be trapped in the cylinder itself. I generally use the Abingdon method for bleeding brakes and clutch (I think this is now refered to as the young assistant technique!) don't go much on these new fan dango gizzmos.
|Bob Turbo Midget England|
|<But absolutely no clutch>|
When did you last change the m/c ? I have found if the slave has gone the m/c is not far behind.
I think the M/C is fine - The clutch was working fine but I was losing fluid so had to keep topping it up.
Bob - I've got a hole through into the footwell to make bleeding easier so accessis actually not a problem. I'll try and clamp the slave cylinder closed and see if that helps.
Guess I've just got to persevere!
|hi mark, i always find after bleeding the clutch at the slave cylinder you should then bleed the air out by the master cylinder by loosening the clutch pipe slightly where it connects to the master cylinder, then bleed it in the same way ,|
|d a hadaway|
|I have never tried it myself, but have read of a way to bleed "backwards". Basically you attach a clean plastic bottle to string tied to ceiling, or some other similar Heath Robinson set up. The important point being the bottle is higher than the m/c. You then attach a tube from the bottle to the bleed nipple on the slave cylinder. Remove some fluid from m/c. Then pour fresh fluid in the suspended bottle, and then open the bleed nipple. The idea is that the fluid works down the tube into the slave, and up to the m/c, pushing all air with it. Once the m/c fills back up, tighten bleed nipple and job is done - hey presto - no pumping pedals, etc.|
Has anyone tried it?
|Graham M V|
Attach your eezi-bleed, ensuring it is full and the reservoir is also full
Crack the bleed nipple and whilst under pressure pump the pedal - you will feel the difference and hear the air depending on how fast or slow you pump, you will also feel the pedal becoming more and more firm as the air leaves.
Personally i do it by leaving a socket attached to a ratchet on the nipple, although i cannot see when it is bled fully, you can feel when it is working at its best. Underneath is a drip tray to catch all the fluid running down the ratchet handle.
May be a bit messy, but its guaranteed bleed and air free.
|Hi Mark - I've had very similar probs as you.... I first tried a new slave cylinder. This didn't sort the problem so I decided to get a new m/cyl ... still no joy after about 2 litres of fluid going through the system!! Tried both pumping the pedal and the eazy bleed gizmo! Then I wondered about the slave I had bought .... the bleed nipple was a lot smaller than the original one I had and also a tighter fit on the thread. Swapped the bleed nipples over and hey presto .... buckets of pressure on the pedal and a fully functioning clutch - ........just a thought worth a try... make sure no air creeps back into the slave when bleedin... atb - Neal|
|Somebody here once posted a trick where you run a hose from the appropriate front caliper bleed port to the bleed port of the clutch slave. You then open the clutch slave port, and have a helper press the brake pedal while you open the caliper bleed port as needed, pumping brake fluid upwards through the clutch system.|
I've never tried it, but it sure sounds interesting. Naturally, you don't want to empty the brake master in the process... nor overfill the clutch reservoir.
Gryf "Sounds crazy enough to work" Ketcherside
If you havent fixed it yet,I have heard, albeit on another car so not sure applicable to yours, that there is a trick of disconnecting the slave (but not hydraulics) and turn it other way round to allow air to escape more easily, bleed, and then refit
|Graham M V|
|I had the same problem until I attached a vacuum based gadget at the bleeder and pulled the fluid from the bottom (instead of trying to push it from the top). That worked perfectly.|
I have to swallow my words and say Rob, you're right...the master cylinder was weak too so I'm having to replace that as well.
I got to the point of fully-working clutch with the easibleed still attached, using Peter's method of pumping the air through using the pedal, but with the easibleed detached, the M/C is sucking air on the up-stroke and the pedal is failing - so I've got a new master cylinder to fit at the weekend.
A guy who lives close to my garage and works in an MOT centre told me that he always bleeds clutches by attaching a large syringe to the slave cylinder and filling the system from the bottom - works on the same logic as Graham and Gryf's methods, pushing the air out the top (ie the way it naturally wants to go) not forcing it out the bottom (the way it doesn't want to go!)
He said it's what's always done on motorbike clutches and brakes which are known for difficulty in bleeding.
So I'm going to try that on Saturday and will report back on my success (or otherwise).
Thanks for all the help and encouragement, everyone. Driving to work in a Scenic just doesn't set me up for the day in the same way as the midget!
|my two cents worth,|
after replacing the slave, then the master, someone suggested (on this forum I think) that the small flexible hose can expand, so replaced that, I think it was only about a tenner, so nothing to lose, bingo, worked for me... got thru a lot of fluid in the process of bleeding though!
Dave - I've got that one covered! Bought a braided hose too, so everything has now been changed...
Glad you sorted it thats the most important thing, not going to say I told you but every slave I have changed I have always had to change the m/c,the extra pressure finds the weak spots in the m/c, I have found that just replacing the seals is also false economy.
Just thought I'd close this one out for anyone who's interested...
I attempted to use the backwards-bleed method of attaching a large syringe (designed for dosing cows, so 30mm) to the slave cylinder. Couldn't get the hose to seal tightly enough on the bleed nipple to force the fluid in - kept squirting out the side. That may be where the gravity-fed idea came from as the pressure would be lower.
I also have my doubts about the effect on the m/c seals of trying to force fluid through them the wrong way?
So, returned to the 'normal' method I've used before - as described by Peter above - and the system bled fairly easily. So it seems like the root of my bleeding issues were that I hadn't realised the master cylinder was failing as well as the slave cyl.
Car's back on the road, and the pedal feels better than it has since...well, ever since I've owned the car, actually!
You cant close on that, everybody is probably more interested in how you come to have a large syringe for dosing COWS !!!Lol...unless you are a vet ?
Haha Rob - I live in Cornwall, you're never more than a few miles from a shop selling agricultural supplies. Mole Valley Farmers are the greatest - everything a farmer could need; hence pretty much anything a car-bodger and/or DIYist could want and a whole lot more...
This thread was discussed between 19/07/2010 and 04/08/2010
This thread is from the archive. The Live MG Midget and Sprite Technical BBS is active now.