I've noticed that my break pedal is making certain "squeek" sound when pushed (even slightly, by hand), and in first 3-4 pushed it also makes some "puffff-puffff-puffffff..." sound (like some air is coming out of somewhere...). After few pushes pedal is "stiffer", more hard to push and that sounds seems to dissapear. But, then, agai, on next traffic light I notice that again... Apart from that, breaks seems to be workind fine. Is this something that is common for Logan - or something that I should worry about. Btw. car is still under warranty - but, is this something that could be claimed as warranty?

This sounds like you have air in the system !You need to take it in and have the brakes looked at and Bled (bleed the air out)
If you can push the pedal down a long way and after a few trys all feels ok it is air !!!
Now you need to find out where it is coming from !! somewhere there is a leak
so go to your Garage and tell them because it could happen that one time you will press down your brake pedal and there is NOTHING there !
Also have a look at the brake fluid
Stu

Well, it is not pushing the pedal a long way down, and that is why exactly I am confused - I know that when there is some air in the brake system it behaves like what you have just explained.

It is like the first third to the full way down, and then with each (even light) press it becomes stiffer, and stiffer.

But, since it is under the warranty... I'll visit the garage anyway.

Check the brake fluid level!
Anything "funny" with the brakes should be dealt with utmost care!!!

Some colleagues told me that it can be connected with "servo break amplifier" in the car, and there is some rubber gasket that, when malfunction, can produce such sound. But, they say, it normally doesn't happen on cars with low mileage (approx 16.000).

Anyway, I'll visit a authorised service, since it is still under the warranty.

And there goes another one into the "What was broken..." topic!

Just tested in my Logan - when the motor is running, I have the same "puff puff" sound, and the brake has a few centimeters of travel. After turning motor off, for the first few pushes the sound is there, but after 3 or 4 pushes the pedal is much stiffer, and there is no sound.

The car has only 4300 km, and it brakes perfectly. Is it a problem with the servo pump, or just normal behaviour?

The "puff" sound is said to be normal. I do not know about the squeaks because I didn't encounter that.

@stajp: it's normal behaviour. With the engine off you are able to push the pedal because the servo is still pressurized. As the engine is not running pressure won't build and the pedal becomes stiffer. It _will_ brake though but you have to push harder on the pedal.

At my garage they told that the "puff" sound was normal, they even let me sit in two brand new Logans and try the breaks. It was the same.

Do all the Logans have the puff sound or not?

One easy way of checking your brake Servo unit is to press the brake down in the morning with the Engine NOT running .Now keep your foot on the brake and start the Engine and you will feel that the pedal now moves down a bit if it does then the Servo is OK
Stu

there are 3 checks to verify if the brake booster is ok:
1. Run the engine for one or two minutes, and then stop it. If the pedal depresses fully the first time but gradually becomes higher when depressed succeedeing times, the booster is operating properly. If the pedal heights remain unchanged, the booster is defective.
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2. With the engine stopped, step on the brake pedal several times. Then step on the brake pedal and start the engine. If the pedal moves downward slightly, the booster is in good condition. If there is no change, the booster is defective.
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3. With the engine runnig step on the brake pedal and then stop the engine. Hold the pedal depressed for 30 seconds. If the pedal height does not change, the booster is in good condition, if the pedal rises, the booster is defective.
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If these three test are ok, the booster is in good condition.
Even if one of these tests is not ok, check the ceck valve, vacuum hoose and booster for defects.

Dear Klaus,

First of all, thank you very much for this very useful information, on the behalf of all members of this forum! Many of us, not just with Logans, but also with previous cars, have noticed such behaviour of the break system - but, at least me personally, was never sure if that is OK or something that should make me worried about. Now I know

Just tell me, if all those 3 tests are "passed OK", and brake fluid is also OK, then this "squik" sound (occasional) can be from the non-lubricated (?) break pad axle bearing point? Uncommon?

Mine Kadett also has puff sound.......it is perfectly normal. No need to worry, as far as brakes do their job well.

When engine running, vacuum forms in brake amplifier (that is big disc in engine compartment). When you press brake pedal, air goes inside and makes pufff sound.

It is quite common the non-lubrication of the pedal axle at logan and the squick from it.

OK, then "mystery" has been solved! :-)
Thank you all!

By the way, in order to lubricate it, would a short burst of WD-40 spray be enough? Or to use some other grease? ("Silicone", "graphite", etc?)

wd 40 is a short term solution.
Use better a grease

Just any grease would be fine?

I am asking this because I haven't seen this axle and don't know if there are some plastic parts there or not - and because I heard that some type of grease can be "agressive" to certain types of plastic (?)