Hi all, had my mechanic replace clutch master cylinder today, it was going for a couple months with bite getting closer to bottom all the time, eventually I couldnt get into gear. according to the work receipts I got with jeep when I bought it the clutch and slave were replaced and its done about 45k miles since, anyway when I picked her up yesterday I had a great high biting clutch for about 3 miles and 10 gear changes, then two clunky changes and pedal on the floor,couldnt get gear, supposedly system doesnt need bleeding as this is plug and play replacement, anybody have an idea of whats happening here?

It needs bleeding.

And if that doesnt work, it probably needs a new slave cylinder.
Which means taking the gearbox out.

thats what worries me, taking the gearbox out is a big job, im hoping its not the slave as the master replacement worked even if only 3 miles, the strange thing is the system never lost any fluid. i was wondering why there was a bleed nut near where pipe goes into bell housing if these parts are plug and play

Dave is 99.99% correct in these cases....
Although.... doesn't any garage check for crankshaft end float these days when they replace a clutch?
That's the issue I had.
https://www.landyzone.co.uk/land-rover/td4-crank-shaft-end-float-how-do-i-get-rid-of-it.290883/

I would say 100% but as I said above.... it's as though people don't check for movement before refitting the clutch.
As I say in most of my posts now (due to having refitted a good engine from an auto...) - "Do not start your car with the foot on the clutch!!"
the crankshaft bearings are drier than you would want them to be while cranking over, and the added pressure on the pedal causes premature wear on the 4th crankshaft thrust race.
I Hope bleeding sorts it out for you, but if the box comes off - please ask the garage to check for end float of the crank shaft - so you know what you are dealing with.

thanks, im hoping its not the slave as its not been that long since clutch and slave were replaced, the problem has been coming up for a couple of months as when I bought it the clutch pedal did not travel all the way back up after gearchanges but then after a month or so it suddenly started to travel all the way back but the bite got lower and harder to get into gear, since these things are not meant to be bled, i am fearing the worst in terms of slave

Hi

I am having similar odd problems with my TD4 clutch.

Had the car form nearly new and clutch biting point has always been at the bottom end of the pedal travel. About 9 months ago I had the well-known problem of the pedal not returning when pressed also gear changes were difficult. So I fitted a new master cylinder (LUK £96) problem solved, it was like a new car and although the biting point was still low it was a little higher than before. Then 9 months and several thousand miles later gear changes start to become difficult as biting point has moved closer to floor, got to the point where I did not feel it was a good idea to drive the car. Got new master cylinder this time from Amazon at £60 fitted it but only a little better. Thinking that the problem could be a mixture of 10 year old fluid contaminating the new and possible air in the system I tried bleeding the clutch first the conventional way by having a helper press the pedal down and then when that did not work by reverse bleeding by injecting the fluid in via the nipple, still no clutch. Decided to admit defeat and suspecting the slave to the car to independent LR garage.

They fitted a new master cylinder, clutch worked straight away without any bleeding. Picked car up and it was like new again. On the bill I noticed the new master had only cost £56. Then after about a week pedal has to hit floor before a gear change can be made (1st and reverse being the hardest) when I had a close look at the master its leaking. So car is going back to garage for them to sort under warranty.

The moral of the story would seem to be that cheap master cylinders don’t work.

Can any body suggest why the LUK could have failed after only 9 months? Other than a manufacturing fault. I have looked at one in a main dealer and it looks like a LUK (correct me if I’m wrong) and they want £180 for that.

Will be interested to see if garage fit another cheap cylinder but I may suggest they fit a genuine LR part and I will pay the difference, also hope I can find the receipt for my original LUK as that had a 2 year warranty.

so, bled the system, like a new machine, fairly high bite point running good now for several weeks , pulling trailers with loads of cattle when needed, master cylinder cost £38

My current theory is that since the silly rubber cap scrapes the firewall, debris gets into the master cylinder if opened (Even if you use a bit of cardboard as a shield). I cannot see how a quick coupling can totally avoid an air bubble (or grit for that matter), which will eventially work its way back to the master, and annoy the seal. My plan when fitting a new 'sealed' master cylinder would be to fit the quick connect and totally flush the system with a combination of pressure bleeding and gentle stroking of the piston rod, BEFORE it is fited to the firewall. Even with this there is still a chance there may be a bubble in the slave that might travel back after a few weeks, so you would need to remove the master from the firewall and bleed again and then re-fit.