Intermittent brake failure
I have been experiencing unusual brake failure in 2 vehicles, 2001 Ford F150, 2004 Dodge 1500. Both trucks have perfectly good brakes and operate as expected. Except in the following cases: 1 Wit...
Forum Discussion
KD4UPL wrote:
Have you ever changed the brake fluid? If not it's high time.
That's very likely the culprit.
Brake fluid absorbs moisture from the air.
The more moisture it absorbs, the lower its boiling point becomes.
When it boils, it is no longer an incompressible liquid - so your brake pedal is no longer capable of applying any pressure on it.
Also, the boiling point of fluids decreases with altitude. The higher you go, the easier it becomes for the fluid to boil.
Finally, if the brake fluid has ever been previously replaced, it's possible that the replacement fluid has a lower boiling point than the manufacturer's engineers intended that vehicle to have (e.g., used DOT3 replacement fluid in a vehicle designed to use DOT4 fluid):
(The "dry" boiling points shown on the chart are for brand-new brake fluid, and the "wet" boiling points are for fluid that has had a chance to absorb some moisture.)
