Nearly Wrote of 2 Cars...

Hi All,

Weird One this morning when starting my p38. Everything started fine in this cold weather , Until I pulled away.

As I pulled away and turn't around in my Drive way I rolled forward to then put it into reverse as going forward I pressed the brake to find out it just kept on going to the floor.

So a quick handbrake up to stop the car worked (and stopped me from hitting my other car). I reversed it back and pressed the brake lightly to find out it was working as always has, so took it down the road and did a couple of tests with the brakes and everything was perfectly fine.

Could this just be because I pulled away to quick and the brake didn't have time to prime up etc..? Or is this going to be the start of a bigger problem?

I had the same problem some time back..... Turned out to be accumulator.

Suggest you don't drive it....as above acc. or pump....more likely accumulator if it lost brake pressure overnight.

the Accumulator is there to store hydraulic pressure while the pumps works, so you should never,ever be without brake hydraulic pressure beit delivered from the pump or the accumulator. So it is not a case of driving off to soon before pressure builds up as pressure should be there 100% of the time...so accumulator is shot more than likely.

Clear instructions in manual DO NOT DRIVE UNTIL TRACTION CONTROL LAMP IS EXTINGUISHED this may take up to 40 seconds if the vehicle has been stood for any length of time.

Saint.V8 said:

if it lost brake pressure overnight.

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Was left standing from about 1am through till 9.30 this morning in -3 temp's.

wammers said:

Clear instructions in manual DO NOT DRIVE UNTIL TRACTION CONTROL LAMP IS EXTINGUISHED this may take up to 40 seconds if the vehicle has been stood for any length of time.

Click to expand...

Cheers Wammers for pointing this out, just tested if, and pump ran for about 7-10 seconds then cut off and light went out, followed by brakes being very responsive on a little test drive.

One thing I have noticed is, I left the keys switch to position 2, once it had primed up the pump stopped, then about 10 minutes later the pump kicked in again for 3-5 seconds. Is this normal?

stewd said:

Was left standing from about 1am through till 9.30 this morning in -3 temp's.



Cheers Wammers for pointing this out, just tested if, and pump ran for about 7-10 seconds then cut off and light went out, followed by brakes being very responsive on a little test drive.

One thing I have noticed is, I left the keys switch to position 2, once it had primed up the pump stopped, then about 10 minutes later the pump kicked in again for 3-5 seconds. Is this normal?

Click to expand...

Fluid drains from the accumulator over time back into the header tank. DO NOT drive off until the TC lamp goes out. Quite normal. Although you said the pedal went to the floor that is NOT normal. There should still be a pedal even with no pressure in the accumulator.

wammers said:

Fluid drains from the accumulator over time back into the header tank. DO NOT drive off until the TC lamp goes out. Quite normal. Although you said the pedal went to the floor that is NOT normal. There should still be a pedal even with no pressure in the accumulator.

Click to expand...

By going to the floor I meant when pressing it to try to stop it kept on going, I would say 3/4 of the way down before I popped the handbrake on.

also check your rear brake pipes aint gone/going/leaking

When my brake pump failed, and all pressure was gone from the system, I still had brakes, albeit you had to really shove on the pedal, and the stopping power was very low.
so there is a master cylinder part that just works from foot pressure.

Luckily my system fully depressurised whilst parked.
The worst that almost happened was I reversed across the road into the neighbours fence.
If ( god forbid) the pressure system fails at speed, be prepared to press the pedal really hard, and if you can, pumping helps.

I have a brake pump running light wired on my dash.
It does come on every 15 minutes or so even if the brakes haven't been touched, so the system must allow some pressure to bleed away.

After leaving the car over night, the time waiting for the heaters should see the pump pressure building if it's a Diesel. But I have definitly felt a very soft pedal sometimes in the morning reversing out of the driveway.
But certainly not going to the floor.

You can watch the fluid resevoir fill up and empty, when up to pressure the level lower than when you have worn out the pressure, by pressing the brake pedal with the engine off.