A while back, I noticed the carpet in the driver's side of my 2001 Corsa C was wet. Pushing down on it would reveal a lot of water just sitting there, with a nasty, squelchy sound.
I spent a week trying to dry it out with hot air, to no avail. I then did some research and it turns out this is a common problem with no easy fix.
The car itself was a steal at less than 900GBP with very little wrong with it, and has served me well for the last 6 months. I wasn't about to blow potentially more than half of that on labor to resolve this non-serious problem, so either I was going to fix it, or it wouldn't be fixed.
I'm pretty inexperienced with car repair. Although I've always known my way around a socket set and I'll confidently work with electricals, I still had a big real-world-experience gap. Nevertheless, I had the internet and some helpful colleagues, and I thought it worth a shot. I also found this fantastic video which shows pretty clearly what needs to be done.
Above the pedals, there is a panel in the chassis with a seal around it. Compost and other outside-crap builds up around it, trapping water and rotting the seal. After a decade or so, the seal fails and begins to let water directly into the carpet and soundproofing.
Removing the carpet
The carpet/soundproofing was completely saturated with water and needed to come out before it got too nasty. I set about doing this one weekend, also taking the opportunity to look at the panel and verify the source of the leak using a bucket of water.
Removing the carpet was significantly harder than I had anticipated. The carpet is all in one chunk and needed to be cut out; that is, after various bits of plastic trim and the driver's seat had been removed.
I spent the next few weeks driving around with no carpet/soundproofing, as the chunks of carpet got drier. There were a few sessions of heavy rain, accompanied by puddles as expected.
Last weekend, the weather was finally nice enough to permit the actual fix.
First I had to remove the wipers, plastic panelling under the wipers & wiper motor, detergent bottle and other bits of plastic:
The next step is to get the master cylinder out of the way. This isn't as simple as unbolting and pulling it away as the feed to the clutch cylinder comes out of the right-hand side of the reservoir, and the pipe has very little slack in it; see the spigot on the right:
To detach this pipe without brake fluid going everywhere, I had to use a syringe to suck just enough fluid out of the reservoir that the level was below that of the spigot, but not so low as to expose the brake master cylinder inlets.
After pulling off the clutch cylinder feed tube and unclipping the rigid hydraulic lines from the chassis where I could, I unbolted and pulled the master cylinder away:
The problematic seal is now clearly visible around the black plate behind the brake servo(round black thing). That needed to come off, which was a bit more straightforward than the brake cylinder. This involves yanking the vacuum pipe out of the front of it, and jamming yourself under the pedals to undo a couple of bolts and remove the pin that attaches the brake pedal to the brake servo:
To get to one of these bolts, I needed to remove the accelerator pedal; the hardest part of this was figuring out how to unplug it. The answer is to grab the red face on the side of the plug and pull it toward you; this magically pulls the plug upwards off of the pedal.
After removing the brake servo, you can see the whole seal which I painstakingly extracted with a knife/screwdriver. Here it is half-done:
This was oddly relaxing to do, and took most of an hour.
After cleaning it up with soapy water and an old toothbrush, I resealed it with Plumbers Gold:
It ended up a bit messy, particularly in the bottom-right corner which was quite hard to reach, but as far as I could tell it was well-sealed.
It was then just a matter of doing everything in reverse.
Putting the carpet back
I've been driving around for a week without the carpet back in as I wanted to be sure it wasn't still leaking. We've had a couple of sessions of rain with no puddles, so I'm confident that it's done. It'll probably take an hour or two to get the carpet back in, either today or tomorrow.