2002 Pont Bonneville - Brake Problem Still

[joetngallagher]

Things have been GUD up to today. Something simple has me stumped. Another shop sent me an 02 bonnaville with 173K on it that they had put front pads on and turned the rotors. Backing it out of their shop they almost wrecked it, pedal went to the floor. After quizing the tech he told me he had compressed the calipers without opening the bleeder, I'm guilty of this if it's a late model, and the pedal wouldn't pump up so he decided to try to drive the problem away.... NOT.... I tried cross bleeding it starting with the right rear and had no pressure, left front was the same. Left rear and right front have pressure. I suspected fluid comtamination and flushed the system. Still no pressure on R/R & L/F. Plenty of pressure on both master cylinder ports. So I bit the bullet and bought the control unit, thinking the damage was too deep. Still no pressure on R/R & L/F. All I can say is %$#*&%. In 44 years I've never been stumped by a hydraulic problem......until now.
ANY IDEAS??????????? Joe Gallagher....Down in the hille of Tennessee working on retireing 4/22/10. Hope I get the Indian done by then.

[steven kiser]

we all know that the braking systems still work on the tandem theory. i think i'de lean towards the hydraulic abs module. i bet if you pressure bleed nothing will come out of the effected wheels. i've seen plenty of issues like this and the fix being anything from an incorrect rotor, caliper misaligned etc. i think that the valve in the abs hydraulic module is stuck in between and causing this issue or along these lines with these symptoms it sounds like someone crossed a like at the hydraulic block.........................

[joetngallagher]

I ALREADY PUT A NEW HYDRAULIC CONTROL ON IT

[steven kiser]

NO NEED TO YELL JOE. i thought when you said control unit you meant module. a honest mistake. pull the a.b.s. fuse and see what happens. the OTHER thing to consider is (i read the post twice to be sure not to make a mistake again) it appears that like me you're the shop that gets all the fubar's from other shops. i learned a long time ago that i take everything they put in, box it up, put it into the trunk. i mean all. once we touch the vehicle as a rule we're held responsible for future failures. i would strongly suggest that the l/f be looked at real carefully. the caliper
may be not seated properly, rotor way to thin, bad flex line, etc. i'm sure that you took all that into consideration but still would replace rotors, install loaded calipers with mounts, an flex lines. if he collapsed the pistons he may have let the caliper drop and has damaged the line. i've also had cars in my shop where there was some creativity performed on it and when a job was a maintenance procedure the micky mouse was removed and issues arose. i find it kind of wierd that the other shop didn't try all sorts of things before it was sent to you. do brakes, can't get pedal, send to joe...... off the top i would think that the lines at the module were somehow crossed. i know of very few "tech's" that would throw the towel into the ring if all that was done was to reline the front brakes. an example of how easy things can go awry is when we would resurface all rotors i had a fairly decent amount of rotors already resurfaced and ready to go. we would swap out and resurface later. on one particular module there were two styles of rotors. solid and vented. vented came off and solid went on. everything looked great but the brakes sucked. went a bit crazy for a while because we did the brakes and we "never" make mistakes. i went to the catalogue and saw the asterisk that led me to answer. i ordered all new with both options. we had sold the rotors to the customer as used and the original ones were in the recycle bin and it was fairly full of scrap and i couldn't be sure of what ones came off it originally. problem solved. since i see your target retire date i'm kinda thinking we're the same type of tech. old school, thrown into the maelstrom of new vehicles. ne thing that i must always remember is that even new parts fail. i had a customer come in with a dead battery. we replaced it and a few weeks later it was towed in with a dead battery. we spent many hours, paid for a few more tows, before i started at the beginning again. you see i assumed that the battery was good since it was new. it wasn't, it had a bad cell. that stuck with me and since then no matter what i always start at the very beginning. i'm just babbling here not preaching, yours was the only post and as always i got a lot to ramble about. i really like to communicate with shops like mine that are the go to shop when other shops, dealers included (on models that are antique to their tech's). i had a person that came into my shop for a quote to repair the heating system on their beemer. gave them a price and the acted like i shot their dog. we all know how we feel about a good dog. well the long and short another shop dropped the same car off for a heating problem i quoted a price 10% more than i had quoted the customer when it was in my shop. i got the approval and did the work. now the frosting, a few mos later while my wife and i were at a local grocery store i ran into the owner of the beemer. i asked ( i was so excited, like a kid in a candy store) if the car still had a heating issue. she told me is had been repaired at another shop and she was very happy with the work and it was a more reasonable price than the one i had given her. i was giggling like a little kid and had a vacation smile on my face. i told her that i has a car that could have been the sister to hers in my shop a few mos ago with a heating issue. i repaired it and actually charged a bit more than i had quoted her. when i saw her expression i knew i had hit what i was looking for. it was the best christmas present that i got that year.............again sorry for the ramble.

[Tim Martin]

On those models, don't ya need a scan tool to open and close valves in the hydraulic module when the system is being bled?

[steven kiser]

i've never run into this on gm's. fords yes. we use a pressure bleeder on all systems. i have a bleeder that looks like r2d2 along with a newer one that plugs into a wall socket. the attachments with the newer one are so easily used and it's just so much more user friendly. i'll reverse bleed the clutch hydraulics and it's just so nice not to have to break into a sweat bleeding these systems.

[Bobt1]

We have had a couple issues like this in the past. My one tech is a big fan of line locking the various hoses and seeing if the pedal comes back, this usually gets us somewhere. More often than not, it turns out to be an issue with the calipers. Good luck


BT