Abs vacuum hissing noise

[AndyD]

I have a 21 1500 5.7 non etorque. It drives and brakes fine but each time I have the brake pedal pushed in and then release I hear a very noticeable loud hissing from the vacuum pump for a few seconds after lifting off the brake pedal, I hear it each time I let off the pedal. No lights on the dash or stored codes. Has anyone ever had this happen to them? It’s been like this since purchased the truck.

My friends 21 limited doesn’t do this so wondering if its something I should look into.

 

[Fatherof3]

Welcome to the forum . Are you still under warranty ?

 

[AndyD]

Welcome to the forum . Are you still under warranty ?

Thanks
No, not under warranty.

 

[theblet]

Maybe the brake booster. I would open the hood with the truck running and have someone press the brake while you look to try and narrow down where it’s coming from.

 

[AndyD]

Maybe the brake booster. I would open the hood with the truck running and have someone press the brake while you look to try and narrow down where it’s coming from.

I did and it’s coming out of the electric vacuum pump. Looks like part # 4581991AB.
Just wondering if anyone else hears a hissing/suction sound when releasing their brake?

 

[theblet]

I did and it’s coming out of the electric vacuum pump. Looks like part # 4581991AB.
Just wondering if anyone else hears a hissing/suction sound when releasing their brake?

Gotcha. I don’t recall ever hearing that sound