Clutch Pedal getting stiffer, the longer i drive.
 

I have a problem with my 2008 g37s with 59k miles. The clutch pedal is getting stiffer when i drive the car for around 20-30min . Then when it gets stiff enough, the clutch pedal starts making a plunging sound. The car works perfectly before the 20 min, and the clutch grabs well. I checked the clutch reservoir and its full, no leaks.

When i turn off the car, then turn on. The problem goes away.

What can it be?

Is the fluid lemonade color or iced tea color?

stiffer - subjective, really. stiffer though, is a good thing. beat on it a bit, and the pedal will get stiffer with more resistance, and then once the fluid boils, it'll go soft.

http://img839.imageshack.us/img839/9...0213154655.jpg

Really black

Do i have to do a clutch and brake fluid bleed ?

Dear God yes! It should be almost clear, maybe a slightly yellowish tint. Iced tea color is very dirty. Yours looks like black coffee. The bleed screw is underneath the car. Follow the line going into the transmission, you should see it. It's 8 mm. Bleed all the dirty fluid out and replace with clean DOT 3. Make sure that you bleed all the air out of the system as well. I don't know it that will solve your firm pedal problem, but I wouldn't take it in to a dealership looking like that to get repaired.

The dealership is telling me that they need to bleed the brake fluid also, since its linked to the clutch fluid. Is that true? cause it seems like they are separate.

AFAIK, on this car the clutch fluid is separate from the brake. Personally, I'd use DOT 4 for both. If it was shared, you wouldn't have 2 separate reservoirs.

Your brake and clutch hydraulic systems are two completely separate systems entirely. One has absolutely nothing to do with the other at all. But if your brake fluid is darker than it should be it's a good idea to flush and bleed it too.

You could consider doing this yourself but if you lack the place, tools, skills, or confidence to do it yourself take it in. It doesn't require a trip to the dealership unless you just want to, any brake shop can do it easily.