My 06 F-150 is having an issue with the brake pedal pushing to the floor when I brake slowly but if if the pedal is hit sharply there is much more pressure in the system. What is causing this problem?

 

Change the brake fluid (I go for every 2 years), and bleed them.

 

^^Yup good place to start. Also check your caliper piston seals to make sure there are no leaks.

 

Failing brake master cylinder?

 

Often best seen as fluid on the inside of the tire at 6 o'clock.

 

DUKE,
Haven't noticed any brake fluid leaks anywhere. Will be bleeding system and replacing fluid to see if that is the solution. Thanks for the info.
Dave

 

Yeah, you should replace the fluid. My truck has gone 13 years with the original fluid in there. And I think its pretty much time I put fresh fluid in there. (I'll do that when I do the brakes in the next week or two)

 

As far as I know, my 05 has the original brake fluid as well. Replacing front & rear pads if it ever stops raining. Not sure why you can't drain & replace OEM recommended DOT fluid and use DOT 5.

 

Dot 5 is silicon based and not compatible with Dot 3, 4 and 5.1. You could use 5 if you completely removed the existing fluid, but on the other hand, the seals for 3, 4 and 5.1 are different than 5. 5 is also not compatible with ABS systems. DOT 5 is mainly meant for racing applications.

I purchased DOT 5.1 fluid from RockAuto, it has a chart on the differences for the fluid https://www.rockauto.com/en/moreinfo...=8319080&jsn=1

 

This is actually a scheduled maintenance item in the owners manual.. most people over look this. Moisture gets into the system over time and causes problems.