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johhn14 07-16-2013 07:29 PM

Stiff brake pedal when starting
Hi all

Within the past week I have noticed that the brake pedal is really stiff when I go to start my Jeep (push button). After starting, the pedal depresses like normal and has the travel that I am used to. The problem is only when starting. Previously the pedal would depress.

I did not turn anything up on this forum, but saw elsewhere that it may be related to a broken vacuum and that air may be entering the system. Does anyone here have any experience?

For reference, I have about 48k on my 2011 Overland. Max care covers me through 70k.


wjs81866 07-17-2013 08:40 AM

Re: Stiff brake pedal when starting
Mine does this when it's not been run for 2-3 days in a row; but once started it goes back to normal. Not sure why it does it.

Frango100 07-17-2013 08:48 AM

Re: Stiff brake pedal when starting
It is normal that the brake pedal feels stiff after the engine being off for a longer period. The vacuum which is needed for the brake booster will leak away (or better said, air will leak in) with the engine off and the booster function is gone, its now only your foot pressure which acts on the brakes. As soon as you start the engine, inlet vacuum will be in the brake booster and add to the foot force.
The vacuum will normally stay for a long time when the engine is off. If it doesnīt, there is probably a leak in the brake booster or a leaking check valve.

johhn14 07-17-2013 05:41 PM

Re: Stiff brake pedal when starting
From the time I get to work til the time I leave it leaks away which is certainly less than a few days. Ill have them check it out next time I'm in.

BobsWK2 07-17-2013 06:53 PM

Re: Stiff brake pedal when starting
I've noticed on my 2014 that sometimes it holds the vacuum in the power brake booster for 4-5 days, othertimes it loses the vacuum overnight. No doubt something is wrong but I'm positive the dealer will say its operating as designed.

2012 Summit 07-18-2013 05:49 AM

Re: Stiff brake pedal when starting
Depressing the brake pedal after shutting down the engine will deplete the vacuum in the brake booster. Not saying anyone is doing this, just throwing it out there.

curio 07-18-2013 06:01 AM

Re: Stiff brake pedal when starting
Itīs not that easy any more, if you have front assist the brake has additional sources for activation, interfering with the brake booster.
You can empty the booster by rapid pumping of the pedal (pedal stiffens up)
Basically, as long as you feel the pedal getting "softer" once the engine is running, everything should be alright. Donīt worry if its more rigid in the morning,no problem.

Good luck


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