Why is there air in brakes after changing discs and pads?

Tiny
TATZ2UK
  • MEMBER
  • 2010 VAUXHALL ASTRA
  • 100,000 MILES
I changed the back brake pads and discs one day and everything was fine. Did the same method when changing the front brakes, the next day and a small amount of air got in the brake line. How can this happen when changing discs and pads?
Friday, August 5th, 2022 AT 1:22 AM

3 Replies

Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 43,046 POSTS
Yep, it does happen when the calipers start to age because it pulls through the seals, you could have had air in the ABS module which will make the brake spongy. Have you tried to bleed the system? If so, did it work? If not, you will need to connect a scanner to open the ABS valves.

Here is a guide and video to help you do the job:

https://www.2carpros.com/articles/how-to-bleed-or-flush-a-car-brake-system

Please run down this guide and report back.
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Friday, August 5th, 2022 AT 5:15 PM
Tiny
TATZ2UK
  • MEMBER
  • 2 POSTS
Thanks very much. We did try to bleed the brakes but didn’t do it right after looking through the article. We were taking our foot off the brake when bleeding them which would have explained why they were still spongy. We’ll bleed them properly and that should do the trick.
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Saturday, August 6th, 2022 AT 1:51 AM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 43,046 POSTS
Use 2CarPros anytime, we are here to help. Please tell a friend.
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Saturday, August 6th, 2022 AT 7:45 PM

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