Brake pedal pressure issue

[ponq]

I work with a fleet of Matrix's and one of the drivers lost brake pressure and had a slow speed accident ( a baseball size dent on the bumper ) , and then the pressure re-established itself. This is the second time this has happened in 6 mos. The first time was thought to be an anomoly.

The fleet manager reproduced it once while it was in the parking lot, but the mechanic can't reporduce the problem.

If the problem can't be reproduced, and there is not a recall what can be done? We certainly don't want to let anyone drive this vehicle.

There was a small leak the first time, but none this time, and I think the Matrix might be out of warrantee.

Would anyone feel safe if we just had the master cylinder replaced, or would there still be a question of safety?

We are considering returning it to the leasing company.

[PhatRoyale]

Have you checked the condition of your brake lines?

You might have to bleed the brakes and replace it with fresh fluid.

[ponq]

I'm not the mechanic, and I hope any mechanic would check that first at the sign of a brake problem.

Usually the brakes pressure fades and does not come back if it is a fluid quality issue.

I will ask all of the basics, but I was hoping someone else had seem a similar issue, on any other vehicle.