Solid brakes

[Captain Jack]

Hello,

Lately, when I get in the car in the morning, sometimes the brake pedal is rock solid. Once the engine is turning, it softens up within a few seconds and there are no braking problems otherwise.

It doesn't happen all the time but was wondering if my servo is on the way out? I know it was replaced at about 53k before I bought it nearly 4 years ago and it's now on 145k.

Thoughts?

[steve_earwig]

Once the engine is turning? So you're trying it with the engine off? Or is it taking a while to build up a vacuum once the engine is actually running?

[Captain Jack]

Maybe I didn't explain it properly:

1) Get in the car, touch the brake pedal prior to starting the engine - solid brakes (engine off)
2) Engine starts - brake pedal softens up within a few seconds

[steve_earwig]

That sounds fairly normal. Hold on...Now I get it, I was expecting the vacuum to have dissipated overnight but I just tried mine and it still had some in there. Maybe a vacuum leak?

[Captain Jack]

Vacuum leak is possible - where would I start looking for it? I don't want to end up with solid brakes while driving...

[jonsowman]

This sounds pretty normal to me, as Steve said, you might have a very small vacuum leak, but nothing to be concerned about I don't reckon.

Turn the engine off, and pump the pedal a few times to release the vacuum. It should stiffen up after 4-5 pumps. This is what the brakes feel like without the servo. Put you foot on the brakes and start the engine. It should soften and sink to the floor within a second. If that's all OK then I don't think you've got anything to worry about.

[Captain Jack]

Turn the engine off, and pump the pedal a few times to release the vacuum. It should stiffen up after 4-5 pumps. This is what the brakes feel like without the servo. Put you foot on the brakes and start the engine. It should soften and sink to the floor within a second. If that's all OK then I don't think you've got anything to worry about.

That's exactly what it does. Except that sometimes (like this morning) the pedal was solid - so it sounds like some vacuum leaked out overnight and made the brake solid. This does not happen all the time. Maybe I am turning the engine off while holding down the brake pedal, so the servo isn't running therefore vacuum is squeezed out?

[jonsowman]

That could be contributing, but I would have thought there would still be some residual vacuum in the system.

I reckon there's a very small leak so it's losing vacuum overnight, but if it's building the vacuum quickly (~1 second) after the engine starting then the leak cannot be very serious