Hi.
I have just (yesterday) drove up Porlock hill then dropped down into Lynmouth and straight up the steep hill out again heading towards Barnstaple.As i came up out of Lynmouth i touched my brakes and my foot went straight to the floor and nothing happened
I pumped them a few times and managed to stop,checked fluid and that was full.
Managed to drive on a few miles pumping the brakes then all of a sudden they came back to life and all seems ok.
Is there something i should do regarding the brakes or will everything be ok ?
Did they overheat with the hills ?
Thanks for your help as i am a bit worried with this being my first big trip (450 miles so far)
The van is a 1985 petrol 1.9
Thanks.
lonegunman,
This is taken directly from the 'Brickyard' site to save typing.
What happens when brake fluid boils? okay, so your going down a hill, its a steep one and instead of using engine braking (very important in a heavy camper) and occasional use of the brakes to slow you down you go all the way down the hill on the brakes, the heat generated by the friction of the brake pads against the brake discs causes heat to build up on the disc and in the caliper, this heat is transferred to the brake fluid.
If the brake fluid is old and has a low boiling point then the brake fluid will begin to boil, when the fluid boils it creates bubbles, so when you next go for the pedal you will find it sinks to the floor with very little if any effect on retarding the vehicles speed. Not good, once cooled the brakes return to normal. This is know as brake fade, vaporized or vapor locked depending who you talk to.
So how do I avoid brake fade? by replacing your brake fluid every 2 years as VW recommend (as well as most other manufacturers) The boiling point of your brake fluid can be checked with a hygrometer which samples the fluid and boils it, the temperature at which it boils is displayed on a screen, most good garages have a hygrometer and can carry this check out for you, you can also use a refractometer which I have absolutely no knowledge of so I won't go any further! If you are in any doubt about your fluid change it, you can't take short cuts with your brakes.
How do I replace the brake fluid? My method involves removing the old fluid from the reservoir by means of a large syringe, cleaning the reservoir of debris and dirt, topping up the reservoir with fresh brake fluid and bleeding the brakes through until clean fluid can be seen coming from the bleed nipple. I use a small plastic drinks bottle with a length of clear windscreen washer pipe pushed to the bottom of the bottle with the other end attached to the bleed nipple, clear pipe is used so bubbles of air and clean fluid can be seen coming out.
If you are unsure about carrying this sort of work out then take it to your garage, most garages carry out a brake fluid change for a little as 20 GBP 2004
Which fluid do I use? DOT 4 is the one to go for, DOT 3 has a lower boiling point, DOT4 has a higher one, DOT5 is silicone based and is not to be mixed with anything else. To be able to use DOT5 you would have to completely remove all traces of anything else from the brake system which to be honest isn't worth the hassle involved, but on the plus side DOT 5 is not hygroscopic hence it is used in higher performance cars.
Hope it helps.
Mike.
'Two 'eads is better'n wun even if mine's a sheeps'
Grun
Member Number 1250
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