Brake pedal gets hard after engine shut off

[Chet Judd]

On my 2021 wrangler 2.0 the power brake booster looses it vacuum almost immediately after engine shut off, pedal gets hard. No performance issues exist, no CEL coming on etc.Brakes work fine with engine running. I smoke tested the booster, no problem found. When I smoke test the vacuum system smoke is coming out of the power brake booster pump. Should the booster pump be leaking like that?

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[alphawolff]

You get one, maybe two pushes from the pedal. This is normal. If you had a vacuum issue you'd be getting a vacuum performance DTC

 

[VKSheridan]

My 2020 gets 2 pumps max with the engine off.

 

[Willys41]

On my 2021 wrangler 2.0 the power brake booster looses it vacuum almost immediately after engine shut off, pedal gets hard. No performance issues exist, no CEL coming on etc.Brakes work fine with engine running. I smoke tested the booster, no problem found. When I smoke test the vacuum system smoke is coming out of the power brake booster pump. Should the booster pump be leaking like that?

You need to first hook up a vacuum gauge to the brake booster.
Start it up.
Block the vacuum line going to the motor and let it sit over night.
If you still have vacuum then the booster is fine and the check valve is bad.
I had to replace the check valve on my 2018 Rubicon and now the valve is leaking on my 2020 Willys.

 

[roaniecowpony]

You need to first hook up a vacuum gauge to the brake booster.
Start it up.
Block the vacuum line going to the motor and let it sit over night.
If you still have vacuum then the booster is fine and the check valve is bad.
I had to replace the check valve on my 2018 Rubicon and now the valve is leaking on my 2020 Willys.

Thanks for that. It reminded me that my 2018 is starting to exhibit the same characteristics.

 

[JLake JEEPA]

You need to first hook up a vacuum gauge to the brake booster.
Start it up.
Block the vacuum line going to the motor and let it sit over night.
If you still have vacuum then the booster is fine and the check valve is bad.
I had to replace the check valve on my 2018 Rubicon and now the valve is leaking on my 2020 Willys.

My 2024 Willys has the same bleed down problem but I am wondering if it is safe to tow behind my RV without repairing the checkvalve. I use an automatic RViBrake System. That is a common braking system used by RV'ers and actually depresses the brake pedal 3 times to bleed out the vacuum before you start pulling it down the road. I took it to a Jeep dealer and of course they say there is nothing wrong. Ya, right!

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