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2011 dmax brake pad change brake master cylinder issue


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eins
Novice

Dec 12, 2018, 12:34 AM

Post #1 of 6 (286 views)
2011 dmax brake pad change brake master cylinder issue Sign In

Hello,

with a 2011 izuzu dmax crewcab pickup. it was taken to a mechanic for a brake pad change and an emergency brake adjustment. When The mechanic changed the pads and and adjusted the emergency brake, the mechnic told us that the master brake cylinder needed to be replaced, because the brake pedal went to the floor after changing pads and adjusting emergency brake. Before we took the pickup to the mechanic the brake master cylinder was working fine. Why did the brake master cylinder suddenly need to replaced?

thanks

jorge


Tom Greenleaf
Ultimate Carjunky / Moderator
Tom Greenleaf profile image

Dec 12, 2018, 4:11 AM

Post #2 of 6 (280 views)
Re: 2011 dmax brake pad change brake master cylinder issue Sign In

A reason is master cyl. hadn't travelled that far in a very long time and was crusty inside the bore tore up the pressure seals. I question why an "emergency" brake needed adjustment being a truck don't know what system is used for rear brakes exact models could be different?


Adjustment of a cable is usually only done once or when one is replaced for another reason will be all wrong later depending on exact type of set up when it's time to do rear brake work,


T



eins
Novice

Dec 12, 2018, 9:10 AM

Post #3 of 6 (268 views)
Re: 2011 dmax brake pad change brake master cylinder issue Sign In

The dmax has front disc brakes and rear drum brakes. The rear brakes are for emergency brake adjustment. The mechanic asked for brake pads for front brakes and brake shoes for the rear brakes. OK. Why doesnt a master cylinder travel?

thanks

J


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Dec 12, 2018, 9:22 AM

Post #4 of 6 (261 views)
Re: 2011 dmax brake pad change brake master cylinder issue Sign In

Under normal use the pedal only travels approx 1/4 of the way down. This causes corrosion and garbage to build up in the bore below that area. When you install new pads and do the initial pump up of the brakes, the pedal travels down into the normally unused part of the bore and the rubber seals get damaged.

It's very common for a previously problem free master to fail after a brake job, especially if the system required bleeding.



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Tom Greenleaf
Ultimate Carjunky / Moderator
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Dec 12, 2018, 9:38 AM

Post #5 of 6 (259 views)
Re: 2011 dmax brake pad change brake master cylinder issue Sign In

? They could prove to you master failed from pumping type brake reset after retraction of pistons in calipers to make room. First few tries pedal goes to floor when done and set before you see the thing again hopefully.


I can't know if they messed up or it's a real pressure imbalance now which should show a warning light on NOW. Other is if new shoes only in the back without new drums or turning those to match (not legal in many places) is the drum is legal but a new diameter even a little pedal is lousy for quite out but work.


I'm left to guessing what happens right away when you fixed it as said or they did. Many tech now will still just push back pistons in calipers all the way to install new pads. Rotors should be turned or replaced or you are getting pretty "hack" work IMO and know it's done all the time.


The pressure is from rubber seals like cups inside master that only travel so far normally so if fluid was ever damp (it happens) by itself over time a crust is deeper in the bore tears those seals so it can't do any pressure or fades out fast meaning slow fade to floor.


If they did everything properly this could happen. IDK what they might have done if they bled this that could be all full of air. First scenario could take a no time or over a few day or longer to notice air would be a constant - usually.
Pedal height and feel is highly dictated by adjustment of rear brake shoes to drum also retracted to make room mechanically and adjusted back up as per just how is done since drum brakes were ever used only about 100 or more years they should know you didn't do this.
What still is on my mind is why did they call it adjusting the parking brake? You shouldn't have to unless it was off for another reason should feel better if all done properly.


Does that work? If not the job must be botched it's all out of adjustment(s) for rear pedal will feel like crap to the floor but would have right away they shouldn't have given it back to you that way without finding out why first.


I nor you really know what or how they did this but it didn't come out right. Master seals torn is somewhat common if pumping brakes up even just to set pads till they are close enough to have a pedal feel. A few pumps that's over.


One more: A shop should test drive a vehicle they just did brakes on IMO and wouldn't dare give one back without doing that first. Lots of unknowns they seem to have thrown out a possible reason for you if they aren't sure it's a guess on their part still - not good,


T



Discretesignals
Ultimate Carjunky / Moderator
Discretesignals profile image

Dec 14, 2018, 1:43 PM

Post #6 of 6 (219 views)
Re: 2011 dmax brake pad change brake master cylinder issue Sign In

Another possible situation is that they pushed the caliper pistons back without opening the bleeder valve. That can push contamination into the ABS modulator and cause a low pedal condition.





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