Right front brake caliper dragging

Tiny
DAVID PORTER
  • MEMBER
  • 2004 CHEVROLET TRAILBLAZER
  • 4.2L
  • V6
  • 2WD
  • AUTOMATIC
  • 44,200 MILES
Elderly neighbor asked me to look at brake problem on low mileage vehicle that stays parked in garage mostly. After ten mile warm up, shudder is noticeable on right front when brake applied. I suggested new rotors and pads (do not trust local rotor turning option) and found a seized right front caliper, therefore changed both, bled system and then things started cascading. After bleeding front brakes, pedal was great until I started engine, then pedal would just keep going to floor. Since then, I have changed the master cylinder, power booster as well as checked vacuum, hose and check valve and both front flexible brake hoses and a second right front caliper (due to uneven drag between sides). As well as a complete four wheel bleed, I have basically flushed out all the brake fluid through multiple part replacement and several times have bled the system. Used brand new or re-manufactured parts and all new DOT 3 brake fluid. Why am I still losing brake pedal all the way to the floor when running, but hard as a rock when not? He has spent several hundred in parts and I have have spent way too much time and effort. I have fixed original problem, but what caused the rest and how do I stop this problem?
Do you
have the same problem?
Yes
No
Thursday, February 9th, 2017 AT 8:34 AM

8 Replies

Tiny
HMAC300
  • EXPERT
Have a mechanic bleed the system with a scanner the ABS unit has air in it which is quite common on DIY jobs. He has to open all valves so it will bleed properly which DIY cannot do.
Was this
answer
helpful?
Yes
No
+1
Thursday, February 9th, 2017 AT 9:31 AM
Tiny
DAVID PORTER
  • MEMBER
Are you saying the only way to bleed the brake pressure modulator is by manipulating the brake control module to open the three outlet lines on the BPM (one rear, one left front and one right front) by using a high end data scanner to send voltages to open those lines in order to bleed? Or can it be done manually? Or can it be bled with a scanner that just reads codes? Just to be sure we understand each other, the calipers were replaced, front brakes bled and then this symptom started, so how did the air travel into a closed valve if the car's entire abs system was off (no voltage) while bleeding the air out of the calipers and maybe some residual air in the line between the caliper and the brake pressure modulator (Chevrolet's terminology for the ECU and proportioning valve two pack that makes up the ABS central hub unit electrical and hydraulic).
Was this
answer
helpful?
Yes
No
Thursday, February 9th, 2017 AT 2:06 PM
Tiny
HMAC300
  • EXPERT
You need the high end scanner to do this the auto parts ones just read codes nothing else as far as sending commands. When the scanner is used it opens the dump and isolation valves so it can get all the air out. There is another valve in there which I do not remember but normally that is the one that is the trouble maker as well. Like I said this is quite common on DIY brake jobs. You can try a power bleeder it may take care of it but if not a scanner must be used.
Was this
answer
helpful?
Yes
No
+2
Thursday, February 9th, 2017 AT 4:06 PM
Tiny
HMAC300
  • EXPERT
It is the brake pressure modulator valve that causes the problem it can be a spec of dirt even with power off as it has to open anyhow to direct the pressure to left front/right front and rear.
Was this
answer
helpful?
Yes
No
+1
Thursday, February 9th, 2017 AT 4:09 PM
Tiny
DAVID PORTER
  • MEMBER
As suggested, I took it to local Chevy Dealer (only shop that had the scanner needed locally) and they did an active ABS bleed and complete system flush for $50. Not too bad. 1 service manager out of 5 local shops worth of Techs had ever come across this before, myself included. I am ASE certified in brakes (and 4 others areas) since 83 and I have never had backward airflow into the ABS setup from changing out a stuck caliper or even seen the scenario on an ASE test. I even went to Chevy dealer and asked if that exact scenario was possible right before I talked to you. Their reply - probably an internally collapsed flexible brake line! But after you shared this with me and I talked to almost every Tech around here, only ONE person, an ex- Chevy service manager - now at a Chrysler dealership - was familiar with and recommended the same procedure. Closest large town dealer wouldn't even offer advice - "$99 and we will troubleshoot." This problem is not as common a problem as you might think - at least not around here. But when I went back and asked local Chevy dealership if they had the right scanner and the capability - the service manager's superior looked it up on the shop's computer, quoted the price and followed through. Simple procedure IF you have the right scanner. Brakes work great now. Pedal travel still seems long and spongy to me just idling, but when driving the brakes work great with very little effort or travel. Chevy says that long travel is normal on that model. Anyways, Seems to have cleared up the issue. Many thanks - hope you are happy with my humble appreciation and a chicken dinner as this was a favor to an elderly neighbor. Dave P. - Florida
Was this
answer
helpful?
Yes
No
+1
Saturday, February 11th, 2017 AT 12:36 PM
Tiny
KEN
  • ADMIN
Glad you could get it fixed please use 2CarPros. Com anytime we are here to help

Best, Ken
Was this
answer
helpful?
Yes
No
+1
Wednesday, February 15th, 2017 AT 9:55 AM
Tiny
DR.PHILL1999
  • MEMBER
I have had cars do the same thing. If the system is open at air gets in. When you push the brake pedal to bleed the air moves and compresses. That is why we bleed all four wheels when only one caliper has been done. The same goes for the abs module.
Was this
answer
helpful?
Yes
No
Friday, March 30th, 2018 AT 10:17 AM
Tiny
KEN
  • ADMIN
Great addition to this thread! Please feel free to help out whenever you are on the site :)

Cheers, Ken
Was this
answer
helpful?
Yes
No
Friday, March 30th, 2018 AT 10:41 AM

Please login or register to post a reply.

Recommended Guides