[OllieS2]

Hi all,

I hopped into my 2002 S2 yesterday having not run it for a week and a half, during which time the car was garaged. Half a mile down the road I noticed the brake pedal wasn't firming up as it usually does after a few pumps. As I pushed it harder the pedal slowly but surely went down to the stop, with very little braking force applied to the car. The sensation was one of treading on a leaky tyre or air mattress and forcing the air out of it.

I nursed the car back home with very little braking ability. Under the front service panels the brake fluid reservoir was (and still is) full, but there's a hissing sound of escaping air and vapour when the pedal is pumped.

Before I go diving in with spanners, does that sound familiar to anyone - is it predictable which seal / brake line/ other component has failed?

Thanks all,

Ollie

 

[KWYK]

sounds like a brake booster

 

[Aedo]

...
Half a mile down the road I noticed the brake pedal wasn't firming up as it usually does after a few pumps.
...

This is not normal and indicative of a brake problem. If you need to pump the brakes to firm them up there is either air in the system or the wheel bearing are failing. In the first case the air causes the sponginess, in the second the disks not running true push the pads out requiring more pedal travel required (with the first push).

...
As I pushed it harder the pedal slowly but surely went down to the stop, with very little braking force applied to the car. The sensation was one of treading on a leaky tyre or air mattress and forcing the air out of it.
......

Sounds the master cylinder is failing and fluid is leaking back past the piston (thus no loss of fluid) and not providing pressure to the brakes.

sounds like a brake booster

There is no booster in a 2002 Elise - the brakes are unassisted.

 

[<@¿@>]

Sounds the master cylinder is failing and fluid is leaking back past the piston (thus no loss of fluid) and not providing pressure to the brakes.

The master cylinder is not failing, it has failed! The master cylinder needs to be rebuilt or replaced.

 

[DDJ74]

The master cylinder is not failing, it has failed! The master cylinder needs to be rebuilt or replaced.

Yep...been there done that. It's a cheap part unless it's a big bore. So i prefer to replace the whole thing versus rebuild it.

Ebay good source for cheap priced parts...

Lotus Elise Exige Audi TT VW New Beetle Golf Jetta 23mm Brake Master Cylinder | eBay

 

[brgelise]

Agreed on the Master cylinder!

 

[OllieS2]

This is not normal and indicative of a brake problem. If you need to pump the brakes to firm them up there is either air in the system or the wheel bearing are failing. In the first case the air causes the sponginess, in the second the disks not running true push the pads out requiring more pedal travel required (with the first push).


Sounds the master cylinder is failing and fluid is leaking back past the piston (thus no loss of fluid) and not providing pressure to the brakes.


There is no booster in a 2002 Elise - the brakes are unassisted.

I didn't really phrase that very well - it's more that I give the brakes a few squeezes as I leave my garage because the car is stored in a garage that, no matter how often it's aired out or swept, is pretty dusty. A few stabs on the pedal just cleans up any deposits on the brakes and gets the response from the pedal. Up until this weekend the brakes have been a standout feature of the car - only a week ago they were strong enough to suspend a 13-stone mate in his seatbelts when I stood on the pedal! He now wants an Elise - I ought to take commission.

Thanks very much for all the replies diagnosing the fault, appreciate it. The car is now safely at a dealer and I'm just awaiting *that* phone call.

In the meantime I'm about to upload some pictures of my car to my Hello thread in the I'm new section, so check it out if you like.

Thanks again all,

Ollie