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Has anyone ever successfully bled a Freelander 1 (TD4) clutch?

Discussion in 'Car Repairs / Maintenance' started by Avocet, 22 Nov 2020 at 12:52 AM.

  1. Avocet

    Avocet

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    I have to admit I've made a right dog's breakfast of this job from start to finish! I wanted to change the master cylinder (they come pre-filled with fluid, and with a quick-release coupling to connect to the pipe going to the slave cylinder).

    My first cockup, was to order a left hand drive one by mistake! However, the only difference is the pipe, so I swapped that (losing a bit of fluid as I did so).

    It worked, but the biting point was very low, so this evening, decided to bleed it. The result?

    ...it's now worse! Can't engage 1st or reverse with the engine running!

    I gather it's the same system on the Rover 75 too. Just seems impossible to bleed!
     
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  3. Harry Bloomfield

    Harry Bloomfield

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    Under the lid of the master cylinder, there is a rubber diaphragm. The diaphragm prevent air getting to the fluid and also prevent fluid leaking out when the master is on the parts shelf. That diaphragm has to be either removed completely to fill the master, or better - all the middle of it cut out so as to allow it to be topped up. Once the master is disturbed, the diaphragm serves no purpose, other than as a seal for the lid.

    The master doesn't hold much fluid, so keep a close eye on the level as you bleed it. If it is difficult to access, to top up - a syringe as a funnel and a section of fish tank air pipe makes it easier.

    The better way to bleed it, is by pumping fluid in from the bottom, via the bleed nipple and out of the top via the master.
     
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  4. Mottie

    Mottie

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    I find that with clutches like that, if you pump the pedal like crazy until you get some pressure then leave the pedal wedged down with a piece of wood between the pedal and the seat for some time (overnight is best), this allows air to percolate up the pipe. Any air left in the system is expelled into the reservoir when the pedal is released.
     
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  5. Avocet

    Avocet

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    Thanks both. I tried bleeding it from the bottom today. It's a bit better, but still hard to get into 1st and reverse, and bites the minute you start to ease off the clutch. I currently have it wedged with a stick to see if that helps!

    The diaphragm on this one, is more of a "bladder" really. It's open to atmosphere via a small hole in the top of the cap, but of course, the diaphragm prevents moisture entering the fluid as the bladder changes volume. I've left it in there as it's doing no harm.
     
  6. Harry Bloomfield

    Harry Bloomfield

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    As you parted the new master cylinder from the pipe, you will have lost most of what little fluid there was in the MC. Which is the cause of your problem. The only way to fill it adequately and restore your proper clutch, really is by removing that 'bladder'.
     
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  8. Avocet

    Avocet

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    Well I'll be damned! I tried it and hey presto! This morning, the clutch was like new! No sponginess in the pedal, easy engagement of any gear, and a biting point a few inches off the floor!
    However... I then went out this evening in the car and although it was "as good as it ever was", it wasn't quite as good as this morning, and a tiny bit of sponginess has returned. Still perfectly driveable though.

    So how did that work??? Without doubt, there is air still trapped in there somewhere. I wonder if leaving the system under pressure for a long time, might allow air to seep past the seals (which are, perhaps, good enough to seal brake fluid but not air)? Why did some of the sponginess come back? Again, a complete guess, but leaving it under pressure for a while, compressed all the little air bubbles, which then took a while to decompress themselves. No idea whether any of that is true or not, but I can't think of any other way to explain the phenomenon!
     
  9. Avocet

    Avocet

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    No, I only lost about a thimble full - if that. Remember that I was putting the old pipe (which was still full of fluid) back on.

    It has been refilled (several times while I was bleeding it backwards and forwards)! The bladder is still there, because I can't see what problem it could cause and at the same time, it allows the volume of fluid to change without letting air and moisture come into contact with the fluid under it. Surely that's a GOOD thing?
     
  10. Mottie

    Mottie

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    Try it again. Any bubbles that are compressed will immediately uncompressed when the pressure is released so it’s not that. My theory is that most of the trapped air makes its way up the pipe and when you release the pressure, they are ejected out of the pressurised side of the system and into the reservoir. Used to be the only way back in the day to bleed a Marina clutch!
     
  11. Harry Bloomfield

    Harry Bloomfield

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    The MC doesn't have much volume for fluid, but the bladder does take up much of that space - unless the MC is pressurised to compress the bladder, so the more fluid there is really the better - the less chance of air getting in.

    The MC lives in a mostly dry atmosphere and unlike the brake MC, the consequences of moisture being absorbed into the fluid are much less dramatic, yet the brake MC lacks a bladder. There is no good reason for the bladder to be there at all, apart from the rim of it as a seal and it is obviously causing you problems bleeding it effectively. If you researched the issue for the Rover 75 and Freelander, the advice is to cut the bottom out of the bladder.
     
  12. Avocet

    Avocet

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    True enough, the "fade" problems with moisture in the system don't really affect a clutch like brakes do, but the consequences of corrosion in the slave cylinder (gearbox-out job to replace!) make me want to try and keep any kind of barrier between the fluid and the air in place if at all possible! The level in there is fine and unless a leak develops, won't change appreciably now. If anything, I guess it might rise slightly as the clutch plate wears, but I don't envisage it being my car for long enough to find out!
     
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