Hissing sound during start up... then it disappeared?

[PnwGladiatorBuild]

Hey everyone,

I had a weird issue pop up and maybe somewhere here can shine some light on it. During start up last week I got a strange hissing, almost like a dry pump sound for 5 start ups in a row, it would happen during auto start stop as well.

Once I made it home, I got out with my camera to record it and it stopped happening... nothing since that either.

Has anyone experienced this? I got no lights on the dash either!

Makes me nervous.

2022 Gladiator Rubicon Diesel, 15600 miles.

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[Hootbro]

Might be the vacuum pump priming.

 

[PnwGladiatorBuild]

Might be the vacuum pump priming.

Maybe but It only happened for 30 min or so in the last 15k miles... Did it ever happen to yours?

 

[Hootbro]

Maybe but It only happened for 30 min or so in the last 15k miles... Did it ever happen to yours?

Happened on my JL. There has been a few threads of similar complaints of either a hissing at start-up and/or during braking operation. Same symptom of it comes and goes and maybe temp related. Common consensus was the vacuum pump and priming of the vacuum system to include the brake booster because you have your foot on the brake when first starting.

This was the gas 3.6L, but I imagine the diesel also has a similar vacuum system.

https://www.jlwranglerforums.com/fo...i-press-brake-pedal-i-hear-a-loud-hiss.39234/

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