No Brake Fluid!

[COSTASP]

Brakes are working fine. Some leaks were seen 4-5 months ago.
After a check today, the beake fluid reservoir was completely empty.
Why s that happened?
Any Idea guys?
W140 S280 1998

 

[Dec]

You shouldn’t drive that car until the fluid reservoir is toped up and the leaks are found and repaired, I think you have answered your own question.

Dec

 

[television]

Just look under the car on the inside of the wheels, a leak there will show up as a dark patch on the inside of the wheels and tyres, on the chassis a leak will show up as a dark patch, just follow the brake pipes back and easy to check

 

[wireman]

Where were the leaks you found previously?

Once you find the leak inspect the underbody protective coatings (paint and underseal) around the leak area, Brake fluid can remove them down to the metal and the bodywork will rot away in no time.

Wash off spilt fluid with hot soapy water.

If there is no evidence of a leak from any of the exposed parts you may have a leaky master cylinder back seal, the lost fluid disapears into the engine via the servo vacuum pipe, this can occur intermittently and very quickly.

 

[Alex M Grieve]

Where were the leaks you found previously?

If there is no evidence of a leak from any of the exposed parts you may have a leaky master cylinder back seal, the lost fluid disapears into the engine via the servo vacuum pipe, this can occur intermittently and very quickly.

Excellent point wireman. I had that problem with a Rover 105S - diagnosed by accelerating hard and checking for a cloud of white smoke in the rear view mirror.

 

[television]

The only thing here is that there is a non return valve in the line from the vacuum tank to the inlet manifold, the fluid can go into the brake booster when there are no leaks, where it will remain.

I had a 105S great car

 

[42864]

Another place to check for Brake Fluid Loss is under the Driver Side Carpets. If the Master Cylinder is leaking it can run back along the push rod (Pedal to Cylinder) and drip down behind the carpets.

 

[wireman]

We are all looking at the same seal, If there is a pedal servo the servo is betwixt the m'cyl and pedal, fluid will not normaly leak into the car with one of those fitted (like our MBs), the older remote servo units left the m'cyl operating rod inside the car and could leak fluid into the car. that said its worth checking inside the car atop the brake pedal.

Malcolm sorry to disagree but, the non return valve is place to allow exhaustion of air from the servo body and not let air back in to the servo if the engine generated vacuum falls. If fluid gets in the servo it will indeed tend to puddle inside the chamber, but will be drawn into the engine as soon as the brake pedal is released and the air which was admitted (to power the brakes) becomes turbulent whilst being evacuated and stirs up the lost fluid.

The engine may knock when its burning brake fluid and producing smoke. On a petrol engine car failiure of the non return valve car put petrol vapour into the servo body the condensed petrol will attack and destroy the diaphragm in the servo unit.

 

[television]

l.

Malcolm sorry to disagree but, the non return valve is place to allow exhaustion of air from the servo body and not let air back in to the servo if the engine generated vacuum falls. If fluid gets in the servo it will indeed tend to puddle inside the chamber, but will be drawn into the engine as soon as the brake pedal is released and the air which was admitted (to power the brakes) becomes turbulent whilst being evacuated and stirs up the lost fluid.

.

Its still a one way valve though, so that should the engine stop, there is a reserve stored in the vacuum tank to allow several brake stops