Major Problems With Brakes - 2016 Sierra 3500HD

[Lic0rice]

2016 GM 3500HD has intermittent violent front end shaking when braking.

9/25/17 - 29,752 Dealer replaced rotors
1/11/18 - 36,833 Calipers sticking, bolt rubbing - Dealer replaced rotors, shoes, & calipers
7/19/18 - 48,764 Dealer replaced rotors
8/2/18 - 49,540 Modulator valve found to be bad.  Dealer replaced valve, turned rotors & replaced pads

9/13/19 - 74,560 more violent shaking 

- Local dealer said they have no idea what the root cause is 

- Opened a case with GM
- GM ask me to take to a second dealership.  
- 10/2/19  Second dealership did recreate both front calipers failing to release properly while on the rack and test driving. Took calipers apart trying to determine why.  Said they were both contaminated, but they had no idea why.
- Replaced front calipers (originals replaced at 36,833), replaced rotors& slides, but they did not replace the pads because they were at 90%.  Also replaced rear calipers, rotors, pads & fixed issue with parking brake.  Tested hoses but I'm not certain how.
- Drove 150 miles home and I could not touch the front wheels when I arrived home. They felt like a furnace.
- Drove 18 miles to local dealer this morning, 10-3, and they got temperature readings of 413 & 408 on the front rotors
- Both dealerships admit that they have no idea what is causing it.

Edited October 4, 2019 by Lic0rice
correction

[wforrest08]

4 hours ago, Lic0rice said:

Took calipers apart trying to determine why.  Said they were both contaminated, but they had no idea why

Was contaminated with what? How did they decontaminate the system or did they? If it’s engine oil from a failing vacuum pump (according to the recall letter this is possibility) oil can cause rubber seals to swell up. Seen this several times when I was still wrenching with people combining different DOT # fluids (or god only knows what else) together causing brakes to “lock up” or not fully release. 

 

I would hope this wouldn’t have been over looked by both stealerships? 

 

Good read about brake fluid contamination.

http://www.agcoauto.com/content/news/p2_articleid/251

 

edit 

Never mind about the vacuum pump. Yours is a HD I forgot that since you posted in the 1500 section I was thinking about what could be contaminating the system. But contamination could still be the reason why IMO since it kinda fits if you think about this as a reoccurring problem.

Edited October 4, 2019 by wforrest08

[elcamino]

If you take the vehicle in for service you might pay attention to what they are doing.  I had a gov't vehicle (k2500 burban) and could only take to quick lube for oil changes (lowest price ruled) and I caught the moroons adding brake fluid and topping of coolant with bulk products.  I had to watch these young guys like a hawk as they tried always to take advantage of our maint asst program.  I mean they were caught charging for air filters that were never changed.  They seen a state owner plate on it and tried to bilk for more work never needed.  Couple places got banned over it.

[Lic0rice]

Something has to be stopping the fluid from flowing back into the master.....electronics, computer, push rod, second bad modulator valve?  

[RyanTech]

Sounds like the hydro boost unit could be sticking and causing the brakes to drag. This can easily be identified by monitoring the brake pressure pid in ABS data while driving, if it increases while not on the brakes something is causing hydraulic pressure to be applied. 

[Lic0rice]

On 10/6/2019 at 4:43 PM, RyanTech said:

Sounds like the hydro boost unit could be sticking and causing the brakes to drag. This can easily be identified by monitoring the brake pressure pid in ABS data while driving, if it increases while not on the brakes something is causing hydraulic pressure to be applied. 

Would that effect both front and back?  We are only having problems with the front.  It goes back to the dealer today and I will raise the hydro boost issue.  Thanks

[Lic0rice]

FINALLY!!!  GM admitted that this is a known problem.  The master cylinder has an air leak that allows air to be sucked into the cylinder....explains how 2 sets of calipers appeared to have rust in them.  Simple solution is to replace the master cylinder.  Of course, even though this has been the problem since 29,752 miles and it was never properly diagnosed, they will not cover it under warranty.  After this repair is done, I will have spent approximately $2500 because the truck came with a defective part.

 

GM had an opportunity to step-up and have a very satisfied customer.  Instead, they have chosen to have an extremely disgruntled customer who purchases a new delivery truck every 24 months for my company.  The last one we purchased was a GM with the 6.0 motor.  Never again.  Going back to Isuzu trucks.  We have owned 3 and Isuzu has always stood behind them (never a major issue, just small stuff).

Edited October 11, 2019 by Lic0rice

[Penguin VII]

6 hours ago, Lic0rice said:

FINALLY!!!  GM admitted that this is a known problem.  The master cylinder has an air leak that allows air to be sucked into the cylinder....explains how 2 sets of calipers appeared to have rust in them.  Simple solution is to replace the master cylinder.  Of course, even though this has been the problem since 29,752 miles and it was never properly diagnosed, they will not cover it under warranty.  After this repair is done, I will have spent approximately $2500 because the truck came with a defective part.

 

GM had an opportunity to step-up and have a very satisfied customer.  Instead, they have chosen to have an extremely disgruntled customer who purchases a new delivery truck every 24 months for my company.  The last one we purchased was a GM with the 6.0 motor.  Never again.  Going back to Isuzu trucks.  We have owned 3 and Isuzu has always stood behind them (never a major issue, just small stuff).

I'd talk to GM and threaten legal action. Assuming you have the history of the repairs (if not get that first) you should be able to easily get this covered.

 

Get your data together, contact GM and give them one last opportunity, tell them you don't want to find legal representation but you will, make sure to state you have the documentation to back it up. Talk to a lawyer, most likely you will get it covered.