Clutch pedal travel suddenly changed - now bite point in last 2 inches towards floor

Afternoon
Title says it all really.
96' Defender 300 TDi 200k miles
Clutch master and slave cylinders replaced Sept '23
Clutch replaced Oct and Nov '23 (Don't ask....)

Today while changing gear the clutch pedal travel and bite point suddenly changed. There was no clunking or any associated noise, no problem selecting gear, no clutch slippage etc BUT from having a bite point pretty much mid point of travel it change to being much closer to the floor.

The pedal travel is not 'sloppy' or 'spongy'- I can just feel the spring resistance in the 1st section, then feel the bite point and clutch disengage, change gear, then reverse the pedal travel til the return spring takes over.

Doesn't make any difference if the pedal is pumped several times

Checked the fluid reservoir - full.
There does appear to be a gentle 'weep' of fluid on the piston rod, but not so as you would really know, and as I said the fluid reservoir is full.

Having looked through the Forum it would appear that we might have air in the system? If there is what would this point to? As there seems to be a bit of wetness on the piston might there be air entering that way?

Any pointers please before we go ahead with replacing master cylinder (again...)

Thank you

Has your shaft adjusting nut come loose ??

If fluid can get out air can get in.
It is a sad thing today the quality of some spare parts can be poor. Some are even fakes in a well known makers box colours.

Bleed the clutch slave cylinder.
place a drip tray on floor under slave cylinder, then slacken off bleed nipple (just slacken it off do not open it) then put a piece of pipe on the bleed nipple that reaches up to the top of inner wing and into a container, remove the clutch fluid reservoir top, then open the bleed nipple and "gently" press the clutch pedal once, let pedal return then top up the reservoir, repeat several times topping up after each press until clean fluid is coming from pipe, nip up the bleed nipple top up reservoir and replace the top, remove bleed pipe catching the fluid that remains in the pipe in the drip tray, very easy to do this way on your own. Hardest part of the job is getting the top off the reservoir and the dust cap off the bleed nipple, I use a small ring spanner to slacken the nipple and leave it on the nipple before fitting the pipe. But ultimately it sounds like you will need to replace the master cylinder it it is starting to leak.

Thanks everyone - all in all a PITA.

Afternoon,

From what you’ve described, it does sound like there could be air in the system, especially since the bite point has suddenly changed without any slipping or noise. Even though the fluid reservoir is full, a small weep at the piston rod could indicate that air is getting in, particularly if the seal is compromised.

A few things to check before replacing the master cylinder again:

1. Bleed the System Properly – Even a small air pocket can cause inconsistencies in the bite point. Try bleeding the clutch thoroughly and see if the bite point improves.
2. Check for Internal Leaks – A failing master cylinder can sometimes leak internally without a significant loss of fluid. If the seals inside the master cylinder are failing, it might not be building consistent pressure.
3. Inspect the Clutch Fork – Although unlikely given your description, a worn or bent clutch fork can sometimes cause odd changes in pedal feel.
4. Look at the Slave Cylinder Again – Since you replaced both the master and slave cylinder in 2023, it might be worth double-checking the connections and seals for any signs of leakage.
5. Check the Pedal Box & Pivot Points – A worn pedal box or pivot pin can sometimes cause changes in travel without any hydraulic issues.

If bleeding the system doesn’t help and the weep near the master cylinder gets worse, then replacing it might be necessary. Hope this helps let us know what you find!