Bongo Fury

no dont have abs, i pulled out of a turning went 20 meters and pressed the brake at the roundabout and nothing happend, was only doing 20 miles per hour when i started braking and there were just no brakes there. when i pumped them them red brake light came on after 5 or six pumps and flashed on and off as i pumped, this was after i hit the car of course and was parked.
the problem did stump the mechanic who came to see me so i just dont want it to happen again as i may be at speed next time.
any advice on where to start?

Is the cap on the brake fluid reservoir properly? If the brake fluid takes on moisture or water of any kind, it isn't capable of compressing the calipers properly.

Water cannot be compressed.

My second port of call would be the master cylinder itself.

And do the discs have any trace of rust/oxidisation on them after a few brake applications? (the rears take longer to clear the rust) I'd check visually that all the discs have been properly cleared of all traces of oxidisation after a run as a safety precaution

bigdaddycain wrote:Is the cap on the brake fluid reservoir properly? If the brake fluid takes on moisture or water of any kind, it isn't capable of compressing the calipers properly.

Water cannot be compressed.

My second port of call would be the master cylinder itself.

And do the discs have any trace of rust/oxidisation on them after a few brake applications? (the rears take longer to clear the rust) I'd check visually that all the discs have been properly cleared of all traces of oxidisation after a run as a safety precaution

Neither can brake fluid If there is water in the fluid (and up to DOT4 fluid is hygroscopic, attracts moisture) then the water can boil off and turn to steam (hardly likely at 20 mph though). Then the brakes can go to the floor!

My understanding was that brake fluid behaves like hydraulic fluid?

bigdaddycain wrote:My understanding was that brake fluid behaves like hydraulic fluid?

Brake fluid is hydraulic fluid - too much JD, Ste (I've been reading your confessional post)

Oh flip! I'll stcik to off message i think mate!

have you checked your front brake sliders ??
i had new brake pads fitted a while ago and the sliders siezed on my pads got eaten to the metal within 1 week

sorry to hear of your problem-if it was our bongo i would change the master cylinder and the servo.its just not worth the risk of another accident

Hi Ron,I would take the vehicle to a garage and have the system checked and verified.
If this happens again your insurance might walk away.(otherwise)

All the best Mal..

i think maybe thats the best idea. a certificate from a garage saying its all ok could be well worth it should it happen again. insurance when overseas is only third party though (may be worth remembering should you come across to europe) so repairs to the van as up to me anyway but dont want to crash into a jag and have them say no do i.

The van has a two circuit brake system if one system fails the other should give some braking on at least two wheels. I think the bongo is split front to rear, the rear brakes will not be very effective on their own.There will be an increase in brake pedal travel.
However the failure you describe to me is a master cylinder fault. When you press the brake pedal the bleed hole to the reservoir is closed and hydraulic pressure in the primary circuit increases this pushes the secondary piston so that hydraulic pressure is applied to front and rear brakes. if the primary circuit fails for example the seal allows fluid to return to the reservoir no pressure is built up in the primary circuit and the primary piston will travel down the cylinder until it contacts the secondary piston and then pressure will build up in the seconday circuit to apply one brake circuit. A view of the master cylinder is on page 248 of the workshop manual. No fluid is lost as it returns to the reservoir. I have found this fault on several occasions. Sometimes it was possible to link the failure to recent brake repairs. In most cases the pistons in the master cylinder travel only a few millimetres but when a brake system is bled by pumping the brakethe pistons stroke further onto unworn sections of the bore, this is why pressure bleeding is preferred. It would be best to replace with new as all second hand ones will be worn.
Comments about the brake pedal becoming hard without the engine is due to the non return valve in the vacuum line not working. It is usual for the brake servo to hold pressure and allow 4 or 5 applications before becoming exhausted. If the non return valve does not work the the vacuum is immediately lost. easy way to check start engine then stop apply fotbrake and see how many applications before pedeal becomes hard.

brakes just went and i crashed into car in ireland

you must have been going like the clappers !!!!!!!