Brake performance issues

[Matahoe]

As of late my truck seems to be gettting harder to stop. When coming to a stop light it feels like i am going to glide right into the back of the car in front if me. In other words it seems as if I need to press the brake pedal much harder (lack of boost?) than normal. The brakes feel like they aren't grabbing good enough. Not sure if this is a brake pad issue or master cylinder or not. It cant be a hydroboost issue because the system exhibits the same performance weather the engine is on or off. The issue is noticeable weather towing or not. Need help with determining an effective course of action in starting to troubleshoot. Thanks.

 

[Jeff Groves]

It cant be a hydroboost issue because the system exhibits the same performance weather the engine is on or off.

This confuses me.
Are you saying you shut the engine off while driving and tried to stop?
If the pedal feels the same with engine running and engine off in the drive way? I'd suspect the boost.

 

[Matahoe]

This confuses me.
Are you saying you shut the engine off while driving and tried to stop?
If the pedal feels the same with engine running and engine off in the drive way? I'd suspect the boost.

I'm trying to troubleshoot it like a vacuum boost to simplify things. If the pedal feels the same with engine running and also when putting in neutral and turning engine off then I would think pressure related.

 

[swathdiver]

As of late my truck seems to be gettting harder to stop. When coming to a stop light it feels like i am going to glide right into the back of the car in front if me. In other words it seems as if I need to press the brake pedal much harder (lack of boost?) than normal. The brakes feel like they aren't grabbing good enough. Not sure if this is a brake pad issue or master cylinder or not. It cant be a hydroboost issue because the system exhibits the same performance weather the engine is on or off. The issue is noticeable weather towing or not. Need help with determining an effective course of action in starting to troubleshoot. Thanks.

Has your pedal travel changed any? Does it move while sitting at a light? Either way, I'm leaning towards a master cylinder but you should check your pads and check for leaks first. A collapsed hose can also cause this feeling.

 

[Matahoe]

I'll check again but im pretty sure it's not a leaky/bad master cylinder. The pedal is rock solid and holds its height. Will check lines at calipers again. I saw something about checking the brake pressure with a guage at the caliper. I might do that.

 

[swathdiver]

I'll check again but im pretty sure it's not a leaky/bad master cylinder. The pedal is rock solid and holds its height. Will check lines at calipers again. I saw something about checking the brake pressure with a guage at the caliper. I might do that.

You can probably rule out the master then. Consider also a stuck piston or two, she is near fifteen years old.

 

[Matahoe]

Just changed the old rusty factory calipers a few years ago. Preemptive maintenance is my motto. I suppose both the replacements could still be bad. It wouldn't be the first time an overseas re-manufactured caliper wasn't properly gone through. However having two bad ones seems remote from my experience. I am leaning towards a hydroboost or power steering pump as the issue. Who is the power steering guru around here?

 

[Woodblocker55]

My guess hydro boost or vacuum boost is toast .
I'm not going to be one that informs you how much hydroboost unit cost. [emoji106][emoji15][emoji849]

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[Matahoe]

My guess hydro boost or vacuum boost is toast .
I'm not going to be one that informs you how much hydroboost unit cost. [emoji106][emoji15][emoji849]

Sent from my LGL84VL using Tapatalk

Yeah, I was thinking it could be the hydroboost as well. I am going to check the service manual again and see if there is a well defined procedure. Would hate to replace the hydroboost without any proof it really is bad. I also thought about attempting a rebuild instead. I have seen kits on Amazon and ebay.

 

[Woodblocker55]

Yeah, I was thinking it could be the hydroboost as well. I am going to check the service manual again and see if there is a well defined procedure. Would hate to replace the hydroboost without any proof it really is bad. I also thought about attempting a rebuild instead. I have seen kits on Amazon and ebay.

Yes try to rebuild or find someone that has done it .
I have hydroboost in my Yukon XL and motorhome . Still have my fingers crossed there working good yet .

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[Matahoe]

Speaking of the hydroboost unit...I know it gets fluid pressure from the P/S pump. My power steering seems to be way low on assist for as long as I can remember. Parking lot steering maneuvers require both hands trying to turn the wheel. When backing up it definitely isn't a one hand on the wheel and the other over the passenger seat type of vehicle. I replaced the pump a few years ago as well. I cant really remember how it performed before the replacment. I guess it would be more important to start with the pump before jumping into the brakes since they are tied together.

 

[Fless]

^^^^ This. Have the power steering pump pressure checked, especially at idle or low rpms.

 

[Woodblocker55]

I have another post trying to figure out if I have the right pump because it's blowing seals out of my steering gear . I'm guessing owner before me put in a cheaper pump $50 instead of the 7200 lb $119 one . Junk yard was all over it he said if you have hydroboost is one pump if you have a vacuum boost it's another pump. now with it leaking it turns super easy it's a 1 finder easy to turn . It like I have to much pressure.[emoji849][emoji15]

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[TxEngr]

Google N182202780 - Special Coverage Adjustment - Brake Assist Decreased Due to Vacuum Loss

Apparently is for 2014-1027, but I don't know why other model years wouldn't be affected.
I got letters from GM for both my 2015 GMC Sierra and 2016 Chevy Tahoe. Symptoms sound very much like your experience

 

[Matahoe]

Google N182202780 - Special Coverage Adjustment - Brake Assist Decreased Due to Vacuum Loss

I dont think this applies to my vehicle as I have hydroboost and not vacuum boosted. Good to note otherwise.

 

[Matahoe]

Just got a replacement OE GM pump. I think i may have found the issue. Take a look at the following pics. It shows a recessed machined area where the bracket meets the pump. I think this is the problem I am facing. I will have to investigate a bit further on this but it could end up being the cause of many peoples problems involving pump noise and immediate failure after replacement.

 

[Matahoe]