[eyedee]

Hi guys,
Last night I was driving the mito home after a weekend away. I'd been on motorways for an hour and a half and as I drove up the exit ramp and tried to go down the gears whilst slowing the clutch pedal went soft and went all the way to the carpet. I couldn't change gear and coasted the car to a handy parking area. After a minute the clutch pedal stiffened up again and I was able to change gear, but changing gear felt stiffer than usual and the clutch pedal has a weird bounce in it. Selecting first gear is especially hard and stiff. I put cardboard under the car but I cant see any clutch fluid leaking. I'm.not sure what the problem is as I've never experienced this before. Any ideas please?

 

[eyedee]

After 24 hours sitting there are no leaks under the car. I understand that the Mito has a hydraulic clutch, so I wonder if it has got air in the system? But for so much air to suddenly get into the system must surely mean a hose or valve etc. has failed somewhere?

 

[ransoman]

Check the level in the brake fluid resevoir first of all. Then follow the pipework for leaks. Does the clutch feel any better if you pump the pedal a few times?

 

[Skaffen]

I seem to recall you can get "internal leaks" in master cylinders where some fluid can leak back past the piston seal so it doesn't work properly but doesn't leak out externally so you don't have any dribbles and the fluid level can still look fine (I'm no expert on clutch bits and pieces so may have got terminology wrong - but that's the gist of what I'd read somewhere!)

 

[Rockhopper]

I've heard of something similar happening with clutches that have a concentric slave cylinder - the release bearing seizes and boils the fluid in the cylinder - when it cools down it starts working again.

 

[eyedee]

Thanks for the posts guys. I've had a good look at the car and to be honest I'm confused.

The brake fluid reservoir level is more than max, so if any has leaked out it can't be much at all, and there's no evidence of leaking anywhere. What's really odd though is that the clutch pedal now feels absolutely normal and everything's acting perfectly with nice slick gear changes, up and down through the box. I don't get it?! Could be what you mention Rockhopper (not that I know what a 'concentric slave cylinder' is! lol) . Odd though considering the journey the clutch played up was motorway miles and not much use of the clutch, or the brakes for that matter.

 

[Rockhopper]

I think its probably worth changing the fluid before you start investigating more serious potential problems.

 

[eyedee]

I haven't had a chance to change the fluid yet, but I will get around to it asap. In the meantime the car seems to be driving perfectly again. Journeys in town traffic of an hour haven't unearthed new issues or led to repeats of the same clutch problem. Very strange, but not complaining!