# Air getting in brakes? **URL:** \ **Category:** Maintenance/Repairs\ **Created:** [December 13, 2018, 4:36am UTC](https://community.cartalk.com/t/air-getting-in-brakes/130763 "2018-12-13T04:36:52Z")\ **Posts on this page:** 5\ **Page:** 1
**Author:** ![Jackson\_Touchstone](https://avatars.discourse-cdn.com/v4/letter/j/46a35a/32.png) [@Jackson\_Touchstone](https://community.cartalk.com/u/Jackson_Touchstone)\ **Post date:** [December 13, 2018, 4:36am UTC](https://community.cartalk.com/t/air-getting-in-brakes/130763/1 "2018-12-13T04:36:52Z")
I drive a 98 dodge dakota and my brakes are rock solid when i first tap them, then they sink to the floor. We bled the master cylinder and calipers and it fixed it for a little while and then it went back to the way it was. The rubber insert on the cap is loose and probably not air tight. Could this be the problem or do i need a new master cylinder? ---
**Author:** ![Tester](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/tester/32/15976_2.png) [@Tester](https://community.cartalk.com/u/Tester)\ **Post date:** [December 13, 2018, 4:45am UTC](https://community.cartalk.com/t/air-getting-in-brakes/130763/2 "2018-12-13T04:45:53Z")
A brake master may be leaking internally. This means that brake fluid doesn’t leak out of the master cylinder. But the seals inside the master cylinder leak and don’t produce enough hydraulic pressure. Tester ---
**Author:** ![Jackson\_Touchstone](https://avatars.discourse-cdn.com/v4/letter/j/46a35a/32.png) [@Jackson\_Touchstone](https://community.cartalk.com/u/Jackson_Touchstone)\ **Post date:** [December 13, 2018, 4:48am UTC](https://community.cartalk.com/t/air-getting-in-brakes/130763/3 "2018-12-13T04:48:46Z")
So the best bet would be to replace the whole cylinder? ---
**Author:** ![Tester](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/tester/32/15976_2.png) [@Tester](https://community.cartalk.com/u/Tester)\ **Post date:** [December 13, 2018, 4:54am UTC](https://community.cartalk.com/t/air-getting-in-brakes/130763/4 "2018-12-13T04:54:02Z")
It’s a brake master cylinder. That’s the only way it can be replaced. [https://www.rockauto.com/en/catalog/dodge,1998,dakota,3.9l+v6,1314423,brake+&+wheel+hub,master+cylinder,1836](https://www.rockauto.com/en/catalog/dodge,1998,dakota,3.9l+v6,1314423,brake+&+wheel+hub,master+cylinder,1836) Tester ---
**Author:** ![donnaeastman](https://avatars.discourse-cdn.com/v4/letter/d/e0b2c6/32.png) [@donnaeastman](https://community.cartalk.com/u/donnaeastman)\ **Post date:** [January 16, 2019, 9:49am UTC](https://community.cartalk.com/t/air-getting-in-brakes/130763/5 "2019-01-16T09:49:57Z")
If so, chances are you have **air** in your **brake** lines. A hydraulic **braking** system, like the one found in most cars and trucks, relies on **brake** fluid for pressure. … The hydraulic pistons within the **brake** calipers slowly extend to keep the **brake** pads at a uniform distance from the **brake** rotors as the pads wear.