Hydraulic Clutch Slipping? Troubleshooting Guide

Hello everyone,

I have an Audi A6, model year 1998, with the 2.5 TDI engine.

The clutch is hydraulically assisted, but in my car, it's harder to press than in a Golf 2 with a cable system. Isn't that unusual?

Furthermore, the clutch engages very late. But then, it engages fully. It definitely doesn't slip; it just grabs firmly in the last few centimeters of pedal travel.

The car has now driven 180,000 km, but according to what I've heard from various sources, that shouldn't be a problem for the clutch.

'I needed to replace the brake pads for the first time at 120,000 km, and the rotors are still the original ones.'

Okay, now I have the problem that I want to change something. But what could be the cause? Could it be the master cylinder? How can I test it?


Regards,

Sebs.

The master cylinder might not be the problem if you're not losing any brake fluid. Have you changed the brake fluid recently? That fluid is what supplies the brake cylinder.

Possibly the release bearing is slightly defective, but it might not be. The pedal in my Golf 4 TDI was also harder to press than in a Golf 4 1.6. There's always some variation.
As long as the clutch isn't slipping and the engine doesn't stall while driving, just keep driving like that for now.
If you ever compare the clutch of your 2.5-liter engine to that of a Golf 2, you'll notice that the one for the 2.5-liter engine has to be slightly heavier, even though it's only modestly larger.

Thank you for your reply so far.

Well, if a clutch is already assisted hydraulically, then I think it should also be a little easier to operate.

I took over the car from my father six months ago, and nothing has changed since then. When I ask my father if it's always been this difficult to drive, he just says, 'I don't know, you get used to everything.'

If anyone has any other suggestions that might help me, I'd appreciate hearing them!

@Sebs:

Some time ago, I had to drive a company-owned A4 TDI (1.9, 81 kW) for work. I drove that vehicle for approximately 600 kilometers and then switched back to my own A3 TDI.
When I first pressed the clutch pedal, I thought I was pressing into nothing. The pedal forces were extremely different, and there was no defect in either of the two vehicles.
Furthermore, hydraulic clutch actuation does not necessarily mean that the pedal force required is lower than with a cable actuation system.
It simply depends on the design of the system. Depending on how the leverage ratios are designed in the linkage to the cable or to the sensor cylinder, and how the area ratios are chosen, virtually any pedal force can be constructively determined.

Regards,
Alex.

Hi,
If the clutch starts slipping more and more and becomes harder to engage, it's likely about to fail. That's my experience with various older cars.
If you drive 120,000 km with a set of brake pads, you are likely using the engine braking effect as much as possible. However, the constant clutch engagement then leads to increased clutch wear. This is similar to what recently happened with my butcher's W124 D. He is always proud of his low brake wear, but now, at around 200,000 km, the clutch is worn out.
It might not be something you need, but it's probably out there somewhere.