Technical Car/Motor Issues > Hyundai i10 - 12 1.0 Brake master cylinder problem
Thread Author: percy Replies: 9

 Hyundai i10 - 12 1.0 Brake master cylinder problem - percy
Hi, I'd be grateful for any advice on the brake problem with this 2012 20,000 mile i10.
This car belongs to a neighbour, was serviced by Hyundai while under warranty and is now regularly serviced by a mobile mechanic.
The initial problem was the front o/s caliper showing signs of binding.
The mechanic freed up the caliper easily, then the decision was taken to put new pads in.
The o/s slave cylinder pushed back under finger pressure, however the n/s cylinder needed gentle assistance with a g clamp. New pads were inserted on both sides, brake pedal depressed and the problems started.
I've lost a bit of the story here, but essentially the n/s cannot be bled, the pedal is floppy and there is much head scratching. The mechanic talked to a local (non Hyundai) garage that were having a similar problem with an i10 and had installed a new £300 master cylinder to no avail. My neighbour purchased a second hand m/c from eBay which also doesn't provide a cure.
An attempt was made to dismantle the original m/c see how it functioned and what might have failed, but it doesn't appear to dismantle easily. There is very little information available on the braking system.
Has anybody come across this problem/or can throw any light on it?
Many thanks in advance.
 Hyundai i10 - 12 1.0 Brake master cylinder problem - carmalade
Could it be the brake flexi hose to the calliper internally collapsed. It then operates like a one way valve . So flow and return are restrictive
 Hyundai i10 - 12 1.0 Brake master cylinder problem - percy
Thanks for your reply. I forget to say the flexi hose was suspect number one and the first item to be changed, alas no change in the symptoms...
There was some thought that one of the seals in the original m/c may have 'flipped' when the g clamp was applied but disassembly proved difficult so couldn't verify.
I haven't talked in length to the owner since the ebay m/cylinder was installed. It cannot have solved the problem though as a second ebay m/cylinder has been ordered. Time will tell if this one is any better.
 Hyundai i10 - 12 1.0 Brake master cylinder problem - carmalade
Have you tried a power brake bleeder? Usually need one of these to get the fluid through the abs unit
 Hyundai i10 - 12 1.0 Brake master cylinder problem - VxFan
>> There was some thought that one of the seals in the original m/c may have
>> 'flipped' when the g clamp was applied but disassembly proved difficult so couldn't verify.

I was just about to suggest this. Good job I carried on reading the whole thread first. I always opt for slackening off the bleed nipple these days when having to push the piston back into the calliper because of this very reason.

>> I haven't talked in length to the owner since the ebay m/cylinder was installed.

The trouble with 2nd hand parts is you just don't know the history. Did the seller say it guaranteed and tested? Mind you, anyone can say that it has been tested, but actually hasn't been.

Not sure if this helps at all? A diagram of a stripped down master cylinder.

www.99rpm.com/hyundai/brake-master-cylinder-i10.html

www.99rpm.com/media/catalog/product/cache/6/image/b459b361606096bcb3b026720354ac59/b/r/brake_master_cylinder_i10.jpg

 Hyundai i10 - 12 1.0 Brake master cylinder problem - slowdown avenue
well hello. have the brakes ever stuck on, how old was brake fluid
 Hyundai i10 - 12 1.0 Brake master cylinder problem - percy
Power brake bleeding has been tried but not successfully. One problem was matching the Hyundai m/c cap, a new cap was modified but would not hold the pressure ie fluid leaked out around the cap.

The fluid is at most 6 years old though I believe it has been changed successfully in the the last couple of years. There hasn't been a problem with the front brakes before, though at an earlier Hyundai service a problem with a binding rear drum had been corrected.

Mobile mechanic not due to try again until next week, meanwhile, is there anything out of the ordinary with the ABS systems on these cars? Does the system have to be interrogated?
 Hyundai i10 - 12 1.0 Brake master cylinder problem - slowdown avenue
look at the old pads to see if one was more worn or unevenly worn
raise both front wheels and see how they spin . then pump up pedal hard and check pads are freeing , ie spin again

need to find out, is it the hydrollicks or physical

are both sides getting hot.

did you bleed in correct pattern, have you regreased the slide pins
I doubt its the mc
file the pad pins down, file out the carrier slides grind of the pads at the top to large chamfer. bleed again with fresh fluid , best down with a good flow and oscillating. maybe to put a block of wood under pedal to prevent mc seal flip.

hope you changed both hoses.

ive just been through all this my self with rear i10 disc brakes
 Hyundai i10 - 12 1.0 Brake master cylinder problem - percy
With thanks to all for useful comments and diagrams.
Problem now overcome. I pass on comments from my friend and his mobile mechanic.

In the end the 2nd eBay m/c was installed and the system 'pedal pumped' bled with difficulty, the problem seeming to be that the particular m/c fitted to this 2012 car has a 'difficult to fill fluid reservoir'.

Getting brake fluid into the rear compartment of the 'baffled' reservoir was very difficult on a level driveway, car on jacks with all wheels off, also it is not easy to check the fluid level in the rear compartment.
Putting a thin rubber glove over the filling orifice and tapping the diaphragm with a finger helped to transfer fluid into the rear compartment. Very tedious, but solved the problem.

If the correct adaptor for the m/c cap had been available initially, pressure bleeding would have worked ok and the whole sorry mess would have been avoided.

Lessons learned! Thanks again to all.
 Hyundai i10 - 12 1.0 Brake master cylinder problem - slowdown avenue
I also replaced mc from a breaker , I used the original cap to fit with my pressure bleeder , with success. but still had sticking brakes. after replacing hose it was fine. to any body coming here in years to come.i would suggest bleed and rebleed the brakes before opening the hydraulics, take a good look at the pad wear too
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