The pedal falls to the floor after I replace the caliper

Tiny
SPECTROIL
  • MEMBER
  • 2005 ISUZU ASCENDER
  • 5.3L
  • V8
  • 2WD
  • AUTOMATIC
  • 120,000 MILES
I recently noticed one of the front calipers getting stuck, so I replaced the cylinders and hose. During the hose replacement, I left it draining brake fluid until the master cylinder reservoir was empty. I put the new hose, the caliper in position, and filled the master cylinder with fresh brake fluid. I was trying to bleed the system with my friend, but we noticed that the cylinders never came out, the pedal feels "good". We started the car and the pedal went to the ground, we tried to bleed it out again with no luck. Now, I don't have brakes in the car, so I can't use them. :(

Do I need to bleed the master cylinder and maybe the ABS too? Please advise me !
Wednesday, May 26th, 2021 AT 7:35 PM

7 Replies

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,867 POSTS
Hi,

If you allowed the master cylinder to run dry, we have a lot of air to get out.

Let's try this first. Open the bleeder fully on the new caliper. Remove the master cylinder lid and make sure it remains full of brake fluid. Allow the vehicle to sit with the bleeder open for approx 15 minutes. During that time, you should start seeing brake fluid draining from the new caliper. Once it starts leaking, close the bleeder and then manually bleed the brake system.

If you look below, I provided the directions specific to your vehicle for caliper replacement. Review the directions to confirm everything was done properly.

Starting with pic 7, the directions for bleeding the system begin.

_____________________________________

Let me know if that helps. Also, I have seen parts stores provide a caliper for the wrong side. That places the bleeder on the bottom of the caliper and makes it impossible to bleed. That is just a thought. Make sure the correct caliper was used.

Let me know what you find or if you have other questions. If this doesn't take care of the issue, the master cylinder may have been damaged, so let me know.

Joe

See pics below.
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Wednesday, May 26th, 2021 AT 8:09 PM
Tiny
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I will try all that tomorrow morning and let you know what do I found. Thanks a bunch!
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Thursday, May 27th, 2021 AT 8:26 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,867 POSTS
Hi,

You are very welcome. I hope it helps.

Let me know.

Joe
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Thursday, May 27th, 2021 AT 8:38 PM
Tiny
SPECTROIL
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Hi, I bled the master cylinder and now the pedal is almost back to normal. I still need to bleed the other calipers as indicated in your instructions. Do you think an ABS Auto bleed will be needed?
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Friday, May 28th, 2021 AT 1:42 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,867 POSTS
Hi,

If the pedal is solid and feels normal, there is a good chance you got the air out. If that is the case, you shouldn't need to do the automated bleed.

Let me know how things turn out when you finish the final bleeding.

Take care,

Joe
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Friday, May 28th, 2021 AT 5:04 PM
Tiny
SPECTROIL
  • MEMBER
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I still need to bleed it again to make 99.99% sure there is no air in the system. I did a test drive to check how it feels. The Ascender runs and stops a lot better than before. But when I returned home, I check the front rotor's temperature and there were around 450F. Then I lifted the front wheel and try to spin it, but it was almost impossible, I think the brakes still dragging :(. Do you think the issue can be the master cylinder? The issue is presented in the front brakes but not in the back ones.
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Saturday, May 29th, 2021 AT 2:08 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,867 POSTS
Hi,

Do me a favor. When the wheels are hard to turn, open the bleeder on one caliper at a time. If the wheel gets easy to turn, then we know it isn't the caliper or a slide issue. If it doesn't get easier, we will need to remove the brake calipers again and inspect them.

You never removed the master cylinder, correct? Also, since the master cylinder went empty, did you bench bleed the cylinder prior to starting to bleed the brakes at the wheels?

Let me know.

Joe
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Saturday, May 29th, 2021 AT 6:48 PM

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