Very hard brake pedal

[Buttyman]

I've not driven my 2018 power wagon much these days--stuck working from home. I've been taking it out once a week only. During the last two start ups, the brake pedal was really hard--I mean, no travel hard. I pushed the brake pedal, but it wasn't enough to "release" the ignition, so it went to accessory only. I pushed REALLY hard on the brake pedal and it finally engaged the starter and started normally. The brake pedal immediately softened to a normal response. Drove fine. So, aside from the need to drive it more often, what gives? Why the hard pedal after not driving for a while?

 

[KeepRight]

I've not driven my 2018 power wagon much these days--stuck working from home. I've been taking it out once a week only. During the last two start ups, the brake pedal was really hard--I mean, no travel hard. I pushed the brake pedal, but it wasn't enough to "release" the ignition, so it went to accessory only. I pushed REALLY hard on the brake pedal and it finally engaged the starter and started normally. The brake pedal immediately softened to a normal response. Drove fine. So, aside from the need to drive it more often, what gives? Why the hard pedal after not driving for a while?

You can Google the problem. Did you have any extreme outside temp changes? The rubber seals in your master cylinders and brake boost got hardened - temporarily.

Most likely, very small vacuum leak. Resulting is lost vacuum assist... Again temporarily - Until you got the truck started.

Keep an eye on it... But it would be tough to find a small vacuum and quite expensive.

 

[IRSmart]

Mine did the same thing a few months ago. I had the theory that someone had been in my truck and pressed the brake pedal during entry or egress. I noticed both times my door was unlocked.

 

[Buttyman]

That makes sense. I googled and it's either the booster or valve. I checked it at 24 hours and it was fine. I think it just bleeds down over the entire week I let it sit. Not the best thing for a vehicle. Saving gas though!

 

[Gone]

My 18 dose the same its been Like that maybe a whole year still dose i just press harder at start up.. Feels like trapped air In the booster..

 

[bm02tj]

bad check valve ,seal or booster
should be warranty have dealer fix

 

[KeepRight]

My 18 dose the same its been Like that maybe a whole year still dose i just press harder at start up.. Feels like trapped air In the booster..

Air in the brake line would make the pedal spongy or squishy. Unless there's a large leak and something else really wrong - air doesn't just get in there on it's own. It's a closed system.

 

[Gone]

Air in the brake line would make the pedal spongy or squishy. Unless there's a large leak and something else really wrong - air doesn't just get in there on it's own. It's a closed system.

yeh brake system 100% fluid no air.

The brake pedal on the other hand relies on engine vacuum to feel soft and easy to press if its hard just means you lost all the stored vacuum from a leak somewhere

 

[Hydraplane]

Vacuum brake boosters don't hold it forever and I don't have the spec on it. Hopefully someone knowing will chime in before you think something is actually wrong.