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Renault Scenic MK3 PH2 2013 1.5dci 110 dynamique tomtom
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Discussion Starter · #1 ·
Hi all,my name is Michal and i am new to this forum .
For past few months i have issue with brakes in my 2013 Scenic 1.5dci . Problem started around december when i noticed that my brake pedal goes lower and lower.I knew i had to change front discs and pads as they were low so my mechanic did it in january,along with fresh brake fluid. There was little to no improvement .I had to pump the pedal to get it firm, then brakes were ok for a while, it was enough to tip them with foot to make it working right. Again, we pressure bleed the whole system ,this is where its getting interesting. Only LEFT side of the car had dark fluid and air in calipers. To the point when it actually hissed when mechanic opened the bleeding nipple on back left caliper. Right side ,front and back had clean fluid with no air. After the bleeding brakes were fine for maybe 2-3 weeks when it all started again, pedal was sinking to the ground,when pressed gently stays in the position. ABS was working fine when triggered ,tested many times on wet,pump generated 80 to 120bars of pressure,but was slowly loosing it ,even when pedal was pressed in same way.
Eventually ,two weeks ago my mechanic replaced the master cylinder,bleed the system again. For first few days pedal was hard.working from very top.As today,2 weeks later and about thousand kilometers it went down again.Not as much as before,but there is a bit of play before brakes starts to work,1/3 of travel i think. To stop car hard i have to press it with force,brakes feels numb. What's interesting is, when on hill assist ,pedal is stiff and very high. Wheels are warm after yourney,four of them in same way so i assume everything is working fine,but it gets me worried . My wife 2006 megane brakes are very firm and working from the top ,while scenic have mind to its own . To get pressure above 80bars i have to press it really hard. On plus side pedal is not spongy,but as i said brakes are numb ,unless i press the pedal around half of the travel.

Servo is working correctly,brake pedal is firm when pumped with engine switched off ,and when engine is running its slowly going down .

Back discs have a bit of lip ,could that be the issue?
I have access to pyclip and elm adapter if needed.

Any advice will be highly appreciated
 

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Super mod..
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Welcome to the forum .. I had to read your 1st post and then approve it.. all is well and now its live to the members.. :)
 

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Grand Scenic 1.6 2007
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Hi Michal and Welcome:)
Was there any conversataion about the vacuum pump?
 

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Renault Scenic MK3 PH2 2013 1.5dci 110 dynamique tomtom
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Discussion Starter · #4 ·
Hi Brendan.
Yes vaccum is working fine, no air leaks, no hissing. Just took the car for a test drive on empty roads, on way to and from work i have no chance to test it properly. Car stops immediately when pressed hard, abs kicked in once(have good tyres so its hard to trigger the system on dry) Did a good few bashings on the brakes, very effective every time. In result front wheels were hot, back ones warm. What's worries me is that first centimetres of travel when im braking gently. Comparing to my wifes megane nothing happening on the first touch
 

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Pedal sinking is normal in any car, but to the point.
This is not something to be looked over. I would take down calipers and check sliders. Calipers must go smoothly left to right.

As long as they are down, you have to see if pressing on the pedal really pushes piston out.
 

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Grand Scenic 1.6 2007
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Could this be just diesel pedal sink?
What happens at idle if you press the pedal gently?
 

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Diesel or petrol, makes no difference.
Slightly pressing the pedal activates master brake cylinder, closing brake pads to the rotors. If braking piston is jammed, braking is achieved by pulling the caliper instead by push of a piston.

Sry, I thought Michal was asking.
 

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Discussion Starter · #8 ·
Well,car just went trough an NCT(car inspection) and according to them everything is fine with brakes.So happy days. I have to change clutch pedal sensor which releasing handbrake when moving on . Sensor is fine ,just the plastic clip is broken. So i moved the sensor today,to reset the error on the dash(check parking brake),and the pedal got a bit stiffer on the top? Could that have any relation to it? Handbrake is working fine, only problem is you have to release it manually every time
 

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Discussion Starter · #9 ·
I have a little update. We have bleed the system again, but different way this time. Engine runing,20pumps on pedal, then one big pump with bleeding nipple open x5 each wheel. Week later brakes are solid as they should be. Fluid in the calipers was brown like a tea,and the amount of air bubbles went trough reservoir was crazy. Obviously ,old master cylinder was letting the air into the system and abs pump has an air in.No air was going though calipers this time. Happy days,for now anyway lol
 

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Not a method that we'd recommend but it worked....nice one.

If the fluid was like brown tea, that may have been the issue and may still re-occur.
Brake fluid has an age limit, 2-3 years and it should be changed.
As time goes by, the fluid absorbs moisture, which causes some discolouration and in severe cases, rust...nice tea colour.
Then as you use the brakes and they get hot, you boil the water/fluid, steam and air result...causing spongy brakes.

A fluid change may be worthwhile.
 

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Discussion Starter · #11 ·
Whole fluid was changed few months back with pressure method, over 1 liter of fresh fluid was pushed through the systen.Didn't help, as the master cylinder was faulty(i hope its the end of the problems lol). We didn't have access to pressure pump so we decided to try to get rid of air from abs unit this way, and it worked. Im just curious where do that dark fluid came from. Maybe my mechanic didn't flush the system properly
 

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Discussion Starter · #13 ·
Well,brakes were superb for 2 weeks. Went to visit a friend,perfect.Left the car parked there for few hours and pedal is soft again :mad::mad:. Going to bleed them again tomorrow. As Renault says bleed the system till the brakes are fine.

Pedal is catching over half of travel,brakes are fine,car reacts to first touch and then nothing till about half of the travel. Fluid in reservoir is clean as it should be. Brand new ABS pump is about a 1k euro as far as I know, and I'm afraid there is no other choice
 

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Super Moderator Technical Supremo Platinum Member
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That may be suggeting that summat is not moving freely., a pad or caliper sticking??
 

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Discussion Starter · #15 ·
I have full service history of the car from the moment it arrived to ireland. Just before i got it 2 back calipers were done.Since i changed back & front discs and pads. Everything is going down even, wheels are hot after few bashings on brakes. Car went to the garage again, different mechanic this time.He said he will bleed it again.

Brakes were superb for 2 weeks, no sign of weakness during that time, like before. Before they got weaker day by day. I just hope there is a bit of air left somewhere, as pedal is getting hard when pumped. Also hard on hill hold.
 

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Check anyway.
The number of times I have had to fettle the edges of new pads to remove burr or paint is almost every brake change I have done in 40 odd years.
If not clean, it can bind.

Other question is what pads...the make....cheap and nasty ones can also fade
 

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Super fantastic Mod Technical Supremo Nice Guy
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Hard braking for the first couple of hundred miles will also cause fade,
Just saying, if you have been hard braking, then might need to clean the surface of the brake pads also
 

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Discussion Starter · #18 ·
Fading of pedal started before i changed discs and pads in the front.
 

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Super fantastic Mod Technical Supremo Nice Guy
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Sinking of pedal you mean
Fading is when you put your foot on the pedal, and you feel like you are not going to stop
Sinking, if thats whats happening ( Engine off foot hard on the pedal and it drops to the floor ) if dropping so far then stays solid and wont drop any more then its not sinking as such, just bad adjustment on rear calipers, or still got a slight bit of air in the system, or brake fluid is that hot and.or it contains water in it ( Old fluid will do this especially when the brakes get hot )
 

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Discussion Starter · #20 ·
Pedal is stiff with engine off. Stiff also when i pump it while stationary. Its kinda dangerous beacuse it sinks to about half of the travel. Brakes are fine tho, car have stopping power. Will see later today, maybe mechanic will find something. Maybe and hopefully there was a bit of air trapped in the system. Im not in favour to change the abs pump
 
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