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Matt, Engineer
Category: Car
Satisfied Customers: 21990
Experience:  Honors degree in Mechanical Engineering, worked 8 years as a Formula 1 engine engineer.
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I am loosing pressure in my clutch pedal. I have changed the

Resolved Question:

I am loosing pressure in my clutch pedal. I have changed the slave clutch and bled the lines. but it still keeps losing pressure. It seams like air is gettin in some place. No fluid leaks out. Can you help me?

I have a 2001 Freelander TD4
Submitted: 7 years ago.
Category: Car
Expert:  Matt replied 7 years ago.

If you've changed the slave cylinder ( the one at the gearbox end) then I'd say you will have to either rebuild the master (pedal end) cylinder or replace that as well, as its sounds like there's a faulty seal somewhere allowing fluid to leak past the piston and so lose pressure.

New seal kits are just a few pounds compared to the cost of a new cylinder
Customer: replied 7 years ago.



I am able to keep pressure for about a week or so. No clutch fluid leaks out, (I know this because I never have to top up the resevoir) also I am not exactly sure which cyclinder is which, one is internal (under the engine and the other is not) I changed the one that is not and I have assumed it is the slave. Can there be any other causes? I was told by my mechanic that it is a hyraulic problem and not a function problem... How big of a job is it to change the seals? (30 Minutes - 4 hours?) Thanks for your help.

Expert:  Matt replied 7 years ago.

The master is the one pushed by the pedal and the slave is the one down at the gearbox end, if you've changed the one at the pedal end then its likely the slave inside the gearbox will need changing.

sadly this a box off affair as it surrounds the input shaft so expect a days labour to change a £50 part
Customer: replied 7 years ago.
I was told by my mechanic that it is not the gearbox end, because no fluid is leaking at that location? Sadly I don't think we have made any headway with this. How can you confirm that this is the case? Is there any sort of test, or telltale sign that this is the case.
Expert:  Matt replied 7 years ago.

If you've changed the master / pedal cylinder and thoroughly bled everything and the pedal still looses pressure then it can only be the slave cylinder.

If you still have issues with the hydraulics and its good after bleeding but then gets worse after a few days / hours, then I'd try leaving the clutch pedal held down overnight by bracing the pedal against the seat base with a piece of wood or similar, this is to try and force the seals inside the slave to take a set in the right orientation as over time they can shrink and draw air back in when you take your foot off the pedal.

This shrinkage isn't enough to leak any fluid but the gap is big enough to draw air in (gas being harder to seal than fluid) if this doesn't work I'm sorry to say that the slave cylinder is going to need changing.
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