New brake rotors, pads & steel braided lines - pedal needs tapping to be firm...

[sniper_x]

On my 2013 Tahoe LT, I installed new brake rotors, pads, and steel braided lines.
I also flushed the fluid and bled the system.

For several days now, I have had to lightly pre-press or tap/ short-press the brake pedal before I get a solid/firm pedal as I should.

I even took the Tahoe to a brake specialist, and they verified it was bled well and there was no air in the system.
The tech stated that it could be any of several things like the master cylinder, sluggish calipers, etc.

However, this only started after I did the rotors, pads, lines, and flush.

My 2007 Yukon brakes are rock solid - fully stock and have replaced the pads on that one too.
Never had this issue before.

Thoughts?

 

[OR VietVet]

On the 07 you said, "replaced the pads" and that does not require opening the lines. IMO, the brake specialist could be wrong and there is still air in the system. When you had the calipers off, did you clean and lube all contact points and pins? With all tires/wheels off, pump up brakes and apply and then remove foot from brake pedal. Inspect the rest position of each caliper. The relaxed gap between the pad surface and the rotor surface, should be almost nothing that you can see.

 

[sniper_x]

On the 07 you said, "replaced the pads" and that does not require opening the lines. IMO, the brake specialist could be wrong and there is still air in the system. When you had the calipers off, did you clean and lube all contact points and pins? With all tires/wheels off, pump up brakes and apply and then remove foot from brake pedal. Inspect the rest position of each caliper. The relaxed gap between the pad surface and the rotor surface, should be almost nothing that you can see.

"The brake specialist could be wrong and there is still air in the system."

Agreed. I have the GM dealership scan tool and try to bleed the brakes using the built-in ABS bleed process.

"When you had the calipers off, did you clean and lube all contact points and pins?"

Yes.

"With all tires/wheels off, pump up brakes and apply and then remove foot from brake pedal. Inspect the rest position of each caliper. The relaxed gap between the pad surface and the rotor surface, should be almost nothing that you can see."

I am replacing the engine mounts today.
I will check this as I do that work since the front wheels have to be removed and the truck is already on jack stands.

 

[Dustin Jackson]

I don't have a lot of experience with bleeding brakes but I did replace my rubber brake hoses in the front and it took quite a bit to get all of the air out and it didn't seem like I could get all the air in 1 try. I would bleed until no more air bubbles came out, then I would take it for a drive and come back and try to bleed it some more and sure enough more air would come out.

 

[sniper_x]

I don't have a lot of experience with bleeding brakes but I did replace my rubber brake hoses in the front and it took quite a bit to get all of the air out and it didn't seem like I could get all the air in 1 try. I would bleed until no more air bubbles came out, then I would take it for a drive and come back and try to bleed it some more and sure enough more air would come out.

Yes, this is precisely what I did.

What I’m gonna do now is I’m gonna hook up the GM tech2 to the car and let it run the ABS purge program.

We’ll see if that does anything

 

[Geotrash]

Yes, this is precisely what I did.

What I’m gonna do now is I’m gonna hook up the GM tech2 to the car and let it run the ABS purge program.

We’ll see if that does anything

One mistake I see people often make is not closing the bleeder screw when their assistant has the pedal to the floor, allowing a tiny bit of air to sneak back in when they release the pedal.

And I agree with the others that the shop doesn't know what they're doing and it's possible (probable?) that they wanted to materialize a problem requiring further diagnosis and replacement of parts.

 

[sniper_x]

One mistake I see people often make is not closing the bleeder screw when their assistant has the pedal to the floor, allowing a tiny bit of air to sneak back in when they release the pedal.

And I agree with the others that the shop doesn't know what they're doing and it's possible (probable?) that they wanted to materialize a problem requiring further diagnosis and replacement of parts.

Regarding the shop and the possibility they wanted to materialize a problem...

I never take my cars to the shop because I do my all own work (from oil changes to engine rebuilds), but this shop is run by a friend.
He maybe didn't perform the ABS purge program (I know that I didn't) and that is likely the issue.

I'll know more after I finish changing my motor and transmission mounts today and can get to the brakes.
I'll set up the hoses and bottle and then grab the TECH2 tool and run the ABS purge process.

 

[wjburken]

What was your bleeding method and bleed sequence?

Vacuum bleeder? Pump the pedal? Etc?
If pedal pump, did you put anything behind the pedal to keep it from going in too far and damaging the MC?

RR, LR, RF, LF?

 

[Foggy]

Gotta run the abs pump when doing calipers and hoses. Almost the only way to get
all the air out

 

[sniper_x]

F@#K!

Tech 2 ABS automated bleed tried twice

Brake pedal is still worse than my Yukon.

What the hell can I do to absolutely and definitely FIX THIS?!

 

[Charlie207]

When I replaced a stuck caliper, and bled all the fluid from the four calipers (it was baaaad). I did it by myself using a Motive Power Bleeder. I sucked out the fluid resevoir with a turkey baster, then topped it off with fresh fluid. Attached the power bleeder & pumped up to 15 psi.

Then I just cracked the bleeder at each caliper (starting at the farthest away) until clear fluid drained out for a while. I had to top off the resevoir and repump up to 15psi several times, but it worked great. No sloppy brake pedal after.

https://www.amazon.com/Motive-Products-System-Bleeder-Trucks/dp/B000TK9FE8?ref_=ast_sto_dp&th=1

Technically, you're supposed to fill up the bleeder with brake fluid, but I was bleeding two vehicles with different fluid types, and didn't want to contaminate. Using it dry works the same, but you need to be more observant that you don't force air into the system. It's not that hard to observe and add fluid as needed.

 

[sniper_x]

I used a vacuum bleeder system with a master cylinder attachment that kept fluid in the reservoir while I ran the ABS Automated Bleed program.

It had me open & close bleeder screws on each caliper in order.

I thought that would knock it out for sure.

Nope.

 

[mattbta]

These questions have probably already been asked, but figured I would ask again.

1. Are the bleeders on top, ie. calipers put back on correctly?
2. Did you have something behind the brake pedal when manually bleeding to avoid pushing the pedal all the way to the floor?

 

[sniper_x]

These questions have probably already been asked, but figured I would ask again.

1. Are the bleeders on top, ie. calipers put back on correctly?
2. Did you have something behind the brake pedal when manually bleeding to avoid pushing the pedal all the way to the floor?

1. Are the bleeders on top, ie. calipers put back on correctly?

>> YES

2. Did you have something behind the brake pedal when manually bleeding to avoid pushing the pedal all the way to the floor?

>> NO? Why would i want to not push it all the way to the floor?

 

[j91z28d1]

1. Are the bleeders on top, ie. calipers put back on correctly?

>> YES

2. Did you have something behind the brake pedal when manually bleeding to avoid pushing the pedal all the way to the floor?

>> NO? Why would i want to not push it all the way to the floor?

since the master never gets pushed to the floor in a 100k miles, it wears just the top part, but now you go bleeding it and it hit the wear ridge and can damage the seal inside.

that's the theory anyways since a lot of guys have perfectly fine brakes and than all of a sudden after trying to bleed them, they need a new master cyl.

 

[OR VietVet]

The seal inside the master cylinder is shaped a lot like a cup and if the master cylinder is bottomed out it can cause the seal/cup to flip backwards. All of a sudden that seal/cup is in a part of the master cylinder that it is not used to being in and the ridge that @j91z28d1 talks about or seal/cup travel parameters can cause problems and is better to avoid all that. I use a small piece of 2x4 and put it on the floor and the pedal hits the 2x4 and never bottoms out.

 

[sniper_x]

The seal inside the master cylinder is shaped a lot like a cup and if the master cylinder is bottomed out it can cause the seal/cup to flip backwards. All of a sudden that seal/cup is in a part of the master cylinder that it is not used to being in and the ridge that @j91z28d1 talks about or seal/cup travel parameters can cause problems and is better to avoid all that. I use a small piece of 2x4 and put it on the floor and the pedal hits the 2x4 and never bottoms out.

Well crap.

If a new Master cylinder is inexpensive then I'll just eliminate this issue with a replacement.

/facepalm/

 

[sniper_x]

It appears I found someone with a unit new in box for $97.00.
I visually verified it's the same unit and part number as a new one from a GM Genuine Dealer.

I'll try to acquire it, but it'll take a while to reply back with my results (3-4 days) because I can't replace this until the weekend or early next week

 

[Charlie207]

Well crap.

If a new Master cylinder is inexpensive then I'll just eliminate this issue with a replacement.

/facepalm/

2014 GMC YUKON 5.3L V8 Master Cylinder | Shop Now at RockAuto

Brake & Wheel Hub Parts and More for Your 2014 GMC YUKON at Reliably Low Prices. Fast Online Catalog. DIY-Easy. Your Choice of Quality. Full Manufacturer Warranty.

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[sniper_x]

2014 GMC YUKON 5.3L V8 Master Cylinder | Shop Now at RockAuto

Brake & Wheel Hub Parts and More for Your 2014 GMC YUKON at Reliably Low Prices. Fast Online Catalog. DIY-Easy. Your Choice of Quality. Full Manufacturer Warranty.

www.rockauto.com

I found a new unit in box for $97 from a person who had an extra one.
However Rockauto does have them inexpensively too.

I'll look into these too.