[fenge64]

Hi. I've just had the brake fluid changed on my i30 diesel fort the 120 k service. I had no problem with the brakes before but since the oil change the brake pedal slowly pushes to the floor under pressure. This would suggest oil leaking past one of the cups in the master cylinder but would like comments from anyone else who has had the same issue.

Cheers!

[StarSeeker]

Hi and welcome to the forum.

If your brakes were ok before the fluid change and are not now, take it back to the garage.

My guess is, there is probably some air left in the braking system and it needs further bleeding.

[Dazzler]

Yes, a big Welcome..

It doesn't sound "bleedin'" right to me either..

[Surferdude]

And sometimes, if the brake fluid is particularly dirty (not suggesting that is the case here), when you flush the system, a bit (bits) of grit can lodge around the seals and damage them so you no longer have a fully functioning master cylinder.

[Paolo5]

I go for the air in the system suggestion. When there is air in a line and you press the pedal, the air compresses (fluid doesn't) and the pedal moves a lot more than normal and not as much fluid is pushed through the brake lines.

[Surferdude]

I go for the air in the system suggestion. When there is air in a line and you press the pedal, the air compresses (fluid doesn't) and the pedal moves a lot more than normal and not as much fluid is pushed through the brake lines.

You may well be right but reading the original post he seems to be saying that if you maintain pressure on the pedal it continues to creep down to the floor. This is, as he says, consistent with fluid bypassing the seals. Air in the system will make the pedal softer (more spongy) than normal but there will still be a point at which it stops before the floor.

[eye30]

Is it loosing fluid from the holder?

Any signs of fluid around the cylinder area at each wheel?

I'd get back to the garage and ask them to check it for you.

[fenge64]

Hi All

Thanks for the welcome and your replies.
I took it back to the garage and they bled the system again but still had the same result. I use my local independent mechanic for the standard services (with the reluctant approval of the Hyundai dealer) on the condition that he uses genuine Hyundai parts/fluids etc. The mechanic also reckons there might be an issue with the master cylinder but from previous experience the issue of dirt/debris getting stuck in one of the master cylinder seals only really occurs with old vehicles and grubby fluid.

I did see a link on this site for a bulletin about 'What to do before changing or topping up brake fluid in i30s but can't open it. 

[Dazzler]

I did see a link on this site for a bulletin about 'What to do before changing or topping up brake fluid in i30s but can't open it.

Shambes is probably in bed now but if you PM him he might be able to help with that when he gets back up...

[fenge64]

Thanks. I've found another link.

[Paolo5]

Hi fenge64,
Did the service bulletein or mechanic let you know what happened to your brakes?