Greetings and thank you for adding me as a new member.
I have a reoccurring brake problem on my 2005 Ford Club Van that happens only during the winter when temperatures dip below about 15 degrees Fahrenheit.

I will be driving the van for a few minutes without any brake issues.
Suddenly without warning when I want to slow or stop, I find that the brake pedal goes all the way to the floor with no braking ability. Holding the pedal to the floor or pumping the brake causes the abs to pulsate but is no help in stopping the van. After a short time, seconds usually, the pedal returns to its normal height and the brakes work as usual. At no time do any brake warning lights come on the dash. I may go five minutes or 25 minutes without any more brake problems but the brake pedal will suddenly without warning go all the way to the floor again with no stopping ability.

After the last time it happened I called my mechanic from the side of the road (he is very respected and has been in business for over 50 years) and explained the situation. After the pedal returned to normal, He had me hold my foot on the brake pedal to find that the pedal is not spongy and does not slowly sink to the floor. He also had me check the brake fluid to find that the fluid is full and topped off. He said my explanation is not possible.

Again, this only happens on e or twice a year when the temperatures dip below about 15 degrees. Has anyone else experienced this problem?

Thanks,
Bob

 

I do not know if this is the answer to the brake problem, but have replaced the master cylinder in similar situations and got rid of the problem.