Noob Question - broken brake vacuum hose (Split)

[Gti Fly]

SOrry for the noob question,

 

My car has failed it's MOT on the basis that the brake vacuum hose has been noted as split.

 

I've ordered the pipe (£28!) and fitted it myself today,   pretty straight forwards.

 

The old pipe was split at both ends where the hard plastic pipe meets a barbed plastic junction/connector.

 

The pipe I'm talking about is supposedly a vacuum pipe, and it runs from the brake master cylinder (from what I can tell), and runs across the bulk head and to the I guess it's the side of the engine block.

 

Now the old pipe had split,  so I guess it shouldn't have been doing what it's intended job for some time.....

 

 

Now the noobie question is,  what is this pipe,  what's it's purpose techinically (trying to understand the braking system in my head),   and how comes I haven't noticed any issues with the brakes even when stamping on them from high speeds?

 

[fletch101]

Humm the pipe must not have been split all the way through and just perrished. If the pipe was split to right through to center the pipe would be drawing in air from the atmosphere instead of forming a vacuum. So I would of thought no poweraassistant brakes

[Gti Fly]

Well the pipe is split at the ends completely,  it litterally just fell off the connectors, (they are supposed to be a tight push fit) i can post some pics up later,  but there could have been no vacuum from it being in the state it was?!

 

I'll post some pics to explain it better

[fletch101]

Mustn't go to the brake diaphragm then :S

[Breezy_Pete]

The pipe in question goes to the brake servo (a pneumatic device), not the master cylinder ( a hydraulic device).  The servo basically amplifies the effort you put on the pedal, by using the difference in pressure between atmospheric and whatever vacuum level your engine's vacuum pump can deliver.  This could potentially be up to about 14 pounds per square inch, and the Fabia servo is maybe 9 inches or more in diameter, call it 10 for easy maths.  So that's 5-squared x pi for the area of the diaphragm inside, 78-ish square inches, that's a potential extra 14x78 = 1100lbs of effort just by letting air into one side of a metal box.

 

Some nice interactive demos here, Click on the 3 tabs Non-braking mode, Partly-braking mode and  Full-braking mode and the piccie changes to show what happens.

 

Have you driven the car since replacing the hose? I think you may find that you don't have to press the brake pedal quite as firmly now?

[Gti Fly]

Cool, thanks for the detailed explanation.   I've yet to try the car,   the brakes before were actually very good in power and pedal feel.    bite early in the pedal travel and stop the car really well.

 

I'll see if this fix has brought about any postive changes later on,   after the footy match!

[Gti Fly]

Car passed MOT retest,   and the brakes feel fine and strong as before

 

Thanks for the advice

[Molly_Fabia]

I had to replace a split vacuum hose last yr and the symptoms just suddenly presented from nowhere an hour into a two hour journey and they were pretty terrifying, most noticeably downhill from high speed. Foot to brake pedal, pedal is rock hard and not budging. Push the hell out of it and suddenly it kicks in and brakes on just in time to stop me careering into the car in front and/or the roundabout off a motorway junction. It happened once on the motorway and again on the slip road as I was trying to get off to limp the car home.

 

Funnily, the first place I got to, a well known franchise, checked system over and told me all my brake pads and discs were bad and needed changing, £400. I told them categorically that I knew they didn't and I was taking the car home (by which point I'd already deduced it was most likely a vacuum/servo problem from good old research of symptoms). They didn't want to let me take the car and decided there was also a sticking caliper which would make driving it highly dangerous, and (get this!) because I have child seat fitted, I clearly have a young one to think about and I don't want to put her at risk!! She wasn't even with me. They teach this sales talk in mechanic class now or it is reserved to the franchise sales mentors? I was also awed by their money making methods of "replace the easy stuff and work up to the more expensive things when that doesn't work". Sad thing is, if it had been my mother, they would have had her money . They also wanted £24 for bleeding my brakes, which I didn't give them permission to do. Took it to another mechanic for a second opinion, he confirmed the split vacuum hose, told me to be grateful the servo was fine and also concurred that discs, pads and calipers were all good in his opinion too (the fronts were barely worn at that time). Scoundrels.

[Sam84]

Anyone got the code for the vacuum pipe? Mines split and could do with a replacement today. Thanks

[Molly_Fabia]

Anyone got the code for the vacuum pipe? Mines split and could do with a replacement today. Thanks

Try http://www.skodaparts.com/

and http://www.partsbase.org/skoda/fabia-fab-eu/

[Sam84]

Well I ordered a part today: 6Q2612041CD but now I think its the wrong part, I think it should be 6Q2612041AL. any one got any ideas?

 

Thanks Sam

[sepulchrave]

Well I ordered a part today: 6Q2612041CD but now I think its the wrong part, I think it should be 6Q2612041AL. any one got any ideas?

 

Thanks Sam

 

Yes, do what I did and simply cut off the split ends, heat cut ends with hot air gun until soft and push back on to the barbs, job done and as good as new.

[Sam84]

well I checked and I had ordered the correct part even though its listed for a pre 2004 vehicle.

[mac30]

hi

i am new to this site

today i got mot for my fabia 2004 and was fail due to servo vaccum pipe split i already look in this forum regarding this problem but i am looking for picture or part number for this pipe so i can order and replace

waiting for anyone help!!!!!!!!!!!!!!!!!!!!!!!!!!! 

[sepulchrave]

Dude, it always splits on the unions, just cut the split part off, heat the cut end and push it back on, it shrinks back onto the joint and you're only cutting about 15mm off.

[rum4mo]

hi

i am new to this site

today i got mot for my fabia 2004 and was fail due to servo vaccum pipe split i already look in this forum regarding this problem but i am looking for picture or part number for this pipe so i can order and replace

waiting for anyone help!!!!!!!!!!!!!!!!!!!!!!!!!!! 

 

I keep reading this "where do I buy a new part or what is the part number?" I've bought VAG software so that I can look for these p/ns, but for those not wanting to invest in that, either use the on-line VAG catalogues - or visit your local Skoda dealer - that is what their parts department is for. If you give them the right information and the part they source is wrong it is their fault and they will sort it out without you been charged any handling costs.

[TMB]

hi

i am new to this site

today i got mot for my fabia 2004 and was fail due to servo vaccum pipe split i already look in this forum regarding this problem but i am looking for picture or part number for this pipe so i can order and replace

waiting for anyone help!!!!!!!!!!!!!!!!!!!!!!!!!!! 

 

It always baffles me why people ask for help but give absolutely no details about the car.

[mac30]

hi sorry for short information

i got skoda fabia estate 1.2 comfort, 2004

[Breezy_Pete]

mac30: here's a photo of the pipe in question on our 1.2; it comes off the back of the intake manifold just below the throttle body, and (unsurprisingly) heads off to the brake servo on the O/S firewall.  This image is taken across the back of the engine looking from passenger/nearside.  You can just make out the brake fluid reservoir in the top right of the pic.

 

The small arrow points to a part number (1K0612071D) but I think it's just for that 90-degree elbow part, which doesn't help you.  Parts catalogues suggest that this pipe comes 'whole' including non-return valve and both end fittings, but there's a multitude of choices based on 'PR' numbers rather than engine codes, so if you do plan to replace it, you're best off getting a Skoda dealer to look up the required part using your registration number on their system.  If you fancy trying to repair it as suggested by sepulchrave, the most likely problem areas are where the pipe goes over the end fittings, as shown for example by the big arrow.

 

[stevekd]

Not sure if in the correct area I'm on a mobile phone, my sdi breaks have gone hard, I followed the hard plastic pipe to the passenger side, it then goes to a round thing with another pipe soft pipe going into it, that has snapped would that cause my problem? Easy fix? I'm in France till September, can't see how to add a picture.

Help

[stevekd]

Found the pic option

[Breezy_Pete]

Drink a bottle of wine with a genuine 'natural' cork.  Wittle a piece of cork down to make a teeny bung for that hole?

[stevekd]

I like that idea a lot, but will it work?

[sepulchrave]

I would imagine that the soft pipe that is connected to the barb that has snapped off also requires a vacuum which is why it's connected there, however as Wino says, simply blocking that hole will restore your brakes, you can use chewing gum as a temporary fix, epoxy resin is better but getting it off will be a pig and you'll need to heat and soften the pipes to remove it, a hairdryer will do the job nicely.

[stevekd]

hi guys,

ok I taped both ends and breaks are amazing BUT, why is it and what damage or anything else can occur by doing it? I don't understand why it working. 

Cheers 

Steve 

Edited 24 June, 2015 by stevekd