Subject being brake servo vacuum hoses.  Not sure quite how universal this failure is, but I've seen so many now on friends and neighbours' cars I always check them any time I remember to whilst under the bonnet of a Volkswagen Group car. 

The hard plastic sections split where they are stretched over the barbs of hose nipples on the terminations at e.g. the non-return valve.

 

If the hose completely parts company with the bit it's attached to you will lose all servo assistance for the brakes. The brakes still work, but you have to press a hell of a lot harder on the pedal. If you don't know this, you will believe the brakes have failed completely.

Before this catastrophic failure, if the splits develop to the point of leaking significant quantities of air, all sorts of weird fault codes can be thrown up, leading to replacement of non-faulty parts if diligent diagnostic techniques aren't used. Lambda sensors, throttle bodies, all sorts of things could get the blame due to 'false air' entering the intake manifold through these splits. 

 

The splits I've just found were not super-obvious. The first one on the underside, I felt with a fingertip before bringing a mirror out to inspect it. The second split, and worse one was on the front side, facing the engine, and couldn't be seen or felt easily until I pulled the whole assembly out a little to inspect more carefully.

 

How old was this hose assembly on my car?

5 years only.   The original was found in a similar or worse state about that long ago, this was a new genuine replacement then. 

Guess what improvements have been made in materials and design of these hoses since this car was made in 2003? None whatsoever that I can see.

 

Please check your own car's equivalent. Go on, you have some time in the next few days, right?

 

If you find crap like I just did, please photograph it and add to this thread.

 

 

 

 

 

I can vouch for this. Checked a while ago on my car, boom huge crack in the hose. I had a vacuum leak for months and I didn't know why.

Instead of buying a new one which is very expensive, what you can do is carefully and skillfully cut off the broken part, and use heat to mold it on the piece of plastic pipe where it should be connected.

Works a treat

Thanks for adding to this @xyzal. 

 

Shortening and refitting with heat may work if the hose is long enough. On the BBY-code engine in my Polo it isn't, sadly. I've temporarily patched it with self-amalgamating tape and a couple of tyraps, but it will have to be changed again at some point I think.

Just now, Wino said:

Thanks for adding to this @xyzal. 

 

Shortening and refitting with heat may work if the hose is long enough. On the BBY-code engine in my Polo it isn't, sadly. I've temporarily patched it with self-amalgamating tape and a couple of tyraps, but it will have to be changed again at some point I think.

You're welcome. Like you said, I should mention that you must make sure it's long enough after cutting part of it. I have the AQW engine and with heat it was easy (but you need lots of patience) to mold it in any shape you need. 

Why Skoda didn't change this, I don't know. They didn't do anything about the water leaks in the first gen Fabia either.

1 minute ago, xyzal said:

They didn't do anything about the water leaks in the first gen Fabia either

Apart from making it more difficult to remove the panels that leak by changing the fasteners from screws to rivets in 2004! 

Thanks for the heads up, you are right, this is now the time to do preventative maintenance, I found that I had not put any antifreeze in over 2 years ago if I removed the radiator to replace the crash bar, I'm doubting now that I even let any fluid out, perhaps it was already filled with water, it was very clear with no signs of corrosion.

 

I will check the accessible vacuum connections and reinforce them with tywraps.