Has anyone ever had a problem with a brake pedal when the temperature outside is below 15F? The pedal gets hard as a rock and the breaks does not work until I press it for few times.

 

probably moisture in the brake booster.... or in the one-way valve on the vacuum supply hose.
Its not completely uncommon. Its not just a mitsubishi issue, either, as that can happen to a LOT of cars.

 

thanks for answer Manybrews, I set schedule at dealer.

 

After the car taking to the service department at dealer and having the brakes job done (front pads and rotors replaced with bleed braking system) the problem still exists...even better, now the pedal get hard not only after staring the car but also during driving - seems a little dangerous. It happen two times in one day during cold weather. Service department manager says he had never had any experience with such thing. Can somebody help?

 

id recommend replacing the vacuum supply hose for the brake booster. Theeres a valve inside the hose that is probably freezing shut, preventing vacuum from applying the brakes. They brakes WILL still work, but you wont have power assist.
as the temp of the car or the ambient air rises, the issue will disappear.

If its not the hose, its the vacuum diaphragm itself. since thats less likely and more expensive, Id start with the hose. Do NOT use any hose.... get the correct one!

 

thanks, its a big help, I'll check with teh dealer

 

After visiting different mitsubishi dealer and replacing brake booster, the brakes work great

 

I've read that it can be home made, but the brake booster valve hose is obsolete and will not be available after market either. Any ideas?