Engine knocking noise Tahoe 18

[dun7ill]

Hi guys,
In around last months I heard knocking noise from my Tahoe 2018 engine and I went to the GM agent here because my car still under warranty it’s only 12k mileage.
However after they check they said it’s from the vacuum pump and they replace it. After that the sound became clear and higher than before !

In the 2nd time they said we will replace another vacuum pump, then when I went to take my car I heard that sound again and they said it’s normal from vacuum pump and to ensure that you can take off the pump belt and the sound will gone.

Now I’m very disappointed because I still heard that sound so I hope you can help me to specify what’s the problem or from where it’s really come.

note : the sound hide if I hold on the brake pedal.

please find clip link below :
https://www.dropbox.com/s/4ysos5strrw299f/Video 01-04-2020, 2 40 23 PM.mp4?dl=0

Looking forward for your replies.

 

[wjburken]

Hi guys,
In around last months I heard knocking noise from my Tahoe 2018 engine and I went to the GM agent here because my car still under warranty it’s only 12k mileage.
However after they check they said it’s from the vacuum pump and they replace it. After that the sound became clear and higher than before !

In the 2nd time they said we will replace another vacuum pump, then when I went to take my car I heard that sound again and they said it’s normal from vacuum pump and to ensure that you can take off the pump belt and the sound will gone.

Now I’m very disappointed because I still heard that sound so I hope you can help me to specify what’s the problem or from where it’s really come.

note : the sound hide if I hold on the brake pedal.

please find clip link below :
https://www.dropbox.com/s/4ysos5strrw299f/Video 01-04-2020, 2 40 23 PM.mp4?dl=0

Looking forward for your replies.

First off, welcome to the forum.

Can you clarify your statement of “the sound hide if I hold on the brake pedal.”

 

[Big Mama]

Welcome from Virginia if the noise is new it’s not normal and taking the belt off the vacuum pump to convince you the pump is the problem is crazy. Stick with it and reach out to GM customer service if you need to.

 

[OR VietVet]

Welcome to the forum from Oregon and we like pics.

May have to get a GM district rep involved if you keep getting the run around from the dealer. I listened to the video and noticed nothing at first but then the noise became more pronounced. Kind of strange that when holding the brake pedal down the noise stops. That means to me that if the brake system is vacuum operated, not hydroboost, then the problem could very well be related to the vacuum pump. There may be a whole batch of defective noisy vacuum pumps out there.



We recommend that you put all your rig(s) info in your signature so we all don’t have to guess at year, make, model, engine size, trans, rear axle locker…….etc. Makes it way easier on all members that attempt to help, to have that info right up front. It is also recommended that you take a pic of your RPO codes, on the inside cover of the glove box, and post that image in your signature. All this info will greatly help those that will try to help with a problem.


If there is any other info, like upgrades, mods or recent mechanical/maintenance work done, that would be helpful in any post as well. Too many times a question is asked by the poster and after about 10 responses we find out that the poster has done recent work to attempt to fix the problem or work that was done that SEEMS not related to the problem.