Clutch hydraulics failure

[V40addict]

I was at a stop sign and when I tried to put the car into first gear I found it was impossible. The car would not go into gear. I pushed the car to the side of the road and noticed a pool of fluid where I was and also underneath. I figured it was brake fluid. It made sense since the brake pedal all of a sudden had a very mushy feel and the clutch pedal was dead, super soft. I popped the hood open and there was a leak somewhere under the airbox. It seems to come from above the level of the gearbox, there is a hose behind the airbox and I can see a bit of fluid running down that hose , and pooling underneath I lost a lot of brake fluid though, so there could be something else to it.

I am praying it's not a clutch failure where I have to remove the gearbox and change clutch plates. Is it a master cylinder or hose failure or something like that ? I see on YT, a hydraulics failure can contaminate the plates and clutch plates then need to be changed.

It happened totally out of the blue, no warning sign, just after driving on a very bumpy cobblestone road. Car has 120 K miles, 2001 V40, 1.8L petrol. Is this kind of failure common or normal with this model ?

[ITSv40]

Not common, but as always anything can happen.

If you have noticed brake fluid on top of the gearbox, near the airbox, I would suspect the hydraulic flexi hose between the fixed pipe and gearbox has perished. That would be the most obvious cause and the easiest remedied.

Leaking fluid from the slave cylinder would leak into the bell housing and exit under the car. Master cylinder leaking would be under the brake servo. Given the design of the brake reservoir a loss of clutch would be a leak in the clutch system, rather than the brake system.

[V40addict]

Thank you ITSv40 I was mistaken in my description of the problem yesterday, I looked again at the car during the day as opposed to yesterday in the dark, and the leak is not behind the airbox but rather below the battery tray I would say. Problem I don' t see where it comes from apart from a possible puncture in the hose which I may feel with my fingers, but I will need to look with a mirror, it wouldn' t make much sense anyway. The fluid was partially on the hose though, bonnet side. There were a lot of projections on the right side (panels and so on) and on the engine (gearbox ?) within the red circle on the pic. There's a bolt on the gearbox (right side, blurry on pic) that's really wet, but I can't see how a leak would come from that bolt or its associated seal, anyway the gears can be moved when engine is shut, so transmission should be OK, given soft pedals this looks like a hose issue. Note the fluid stain on the road underneath the hose. I didn' t open the fluid reservoir because it was very dirty and I didn' t feel like cleaning it thoroughly before opening. The reservoir looked like it had something in there which would be surprising.

[ITSv40]

Originally Posted by V40addict

The reservoir looked like it had something in there which would be surprising.

The reservoir would still have fluid in the bottom of it as the outlet for the clutch system is about a third of the way up. This is designed so that a leak in the clutch system doesn't affect the brakes. I still think the leak is from the clutch flexi hose.

[magnuz]

There is a brake pipe that passes through the inner wing to the front wheel that is in the area under the air box. It is quite hidden, so often gets overlooked by mot testers & has been known to corrode & fail. If you remove the air box, you should be able to see it. This would cause a soft brake pedal. The clutch hydraulics & brake system also share the same reservoir so could also cause a problem with the clutch !

The thing that you can see in the reservoir, may be a rubber diaphragm type of thing that is attached to the cap. It sometimes hangs down as the reservoir level goes down. It can be pushed back in to the cap.

[V40addict]

OK I now know what caused the failure. Like I said, when I ran my fingers on the hose seen on the pic, I felt something protruding underneath, as if there could be a puncture . We put some brake fluid back in the reservoir just to move the car a couple meters, and I thought I would check that hose where I could feel something odd, and sure enough that was where the leak was !
Now how is it possible that there was a puncture the size of a punch there ? Mechanically I can't explain it . A hose cracks, bursts, dislodges alright, but gets punctured ? The puncture is in the lower part of the hose, where the hose is about parallel to the ground, closer to its junction with the metallic part of the sytem.

What would have happened if I was driving at moderate or high speed when the failure occured ? If I was in gear , I could not use the clutch and my brakes were only working at a fraction of their efficacy. I only had the handbrake to stop, right ? Trying to figure out what would have happened on a highway for example ....