Why change the brake fluid?

Brake fluid is a component, so why should it be changed?  Did you know that the average car driver who travels 10,000 to 15,000 miles a year uses his brakes around 75,000 times?  We can therefore assume that an American RV Motorhome that has the extra weight and travels around 4,000 miles a year probably uses the brakes between 40,000 – 50,000 times.

The number one fear that at least 50% of RV owners have is brake fade.

Las Motorhomes have carried out a brake fluid test on all American Motorhome services since 2003, although we know from our new customers that our competitors have not included this as part of their service.

With a car that is used regularly the brake fluid replacement can be calculated and this is done by the manufacturers who give you the replacement times.  As with your American RV motorhome this is more difficult to do because the majority of them are not used on a daily basis.  This is why LAS think the test should be done on all motorhomes once a year.  Many experts have also campaigned for the brake fluid to be changed annually.  The evidence to support this is based on the fact that glycol-based brake fluid absorbs moisture from the moment it is put into the system.   The fluid attracts moisture through microscopic pores in the rubber hoses and past the seals as it is exposed to the air.  The problem is far worse in wet climates where the humidity is high.

After only a year from the service the brake fluid in the average American motorhome could contain as much as 2% water, whereas after 18 months it could be as high as 3% which will drastically reduce the boiling point of the brake fluid.  When the brakes are used heat is generated by the friction between the brake pads and the brake rotors, some of this heat is transferred to the brake fluid.  With a high content of water this will make the brake fluid boil producing steam, this makes trying to stop the vehicle impossible.  (Brake fade at its worst). This makes the brake pedal shoot to the floor with no brake effort, this is definitely not what you need when going down on an incline.

As the concentration of moisture increases it causes a sharp drop in the boiling temperature.  DOT 3 must have a dry (no moisture) boiling point of at least 400 degrees fahrenheit and a wet (moisture saturated) boiling point of no less than 284 degrees fahrenheit.  Most new DOT 3 fluids exceed these requirements and have a dry boiling point that ranges from 460 – 500 degrees fahrenheit.

What people do not understand is that a water content of 3% in the brake fluid can reduce the boiling point of the brake fluid to a 293 decrease which is getting very close to the manufacturers minimum.

Water contamination increases the danger of brake failure because vapour pockets can from if the fluid gets too hot.  Vapour replaces fluid and is compressible so when the brakes are applied the pedal may go all the way to the floor without applying the brakes!

In addition to the safety issue, water laden brake fluid promotes corrosion and the pitting of calliper pistons and bores wheel cylinders, master cylinders, ABS modules and steel brake lines.

Once again this is why LAS Motorhomes have adopted the testing of brake fluid at every service.

To book your service contact LAS on 01604 861999.