What is the black ball **** type thing in 2.0l BKD engine in Gt tdi engine bay?

[Buzzoff]

Hello people,

While doing a oil & filter change on my golf GT TDI 2.0l bkd, I came across a black ball **** type thing positioned just above the alternator.

I noticed that the plastic engine cover was rubbing against the small 5-6mm hose that went into the black ball thing. I decided to investigate the hose to see if I could protect the rub mark from getting any worse.

It was at that point that I found that where the 5-6mm hose pushed into a spigot inside the black ball thing that infact the spigot had broken away from the black ball thing.

With the engine running I could feel there was a vacume being drawn into the hose.

I called my local VW dealer and I have ordered a new black ball **** type thing (£20ish) should be there tomorrow fingers crossed.
I had to use my car to get to work this arvo so all I did was cable tie the hose safely out of the way of the alternator, then drive 30miles to work.

My question is what does the black ball thing do?

Any ideas?

Cheers,

Dan

[zollaf]

i think you will find its a vacuum resevoir.

[tornadored7]

Hi Dan,

If the Black ball/sphere appears as below;





Then this is likely to be the Vacuum reservoir, used by the tandem (Vacuum and Fuel) pump.

Rather than operate directly through an electrical connection, several important actuators/components are operated using a vacuum generated by the tandem pump, including;

• Brake servo: Power assist for the brake circuit
• VNT turbo actuator: to adjust the turbo boost
• EGR valve: feeding back inert exhaust gases to reduce NOx pollution
• Anti shudder valve: to prevent engine shake on shutdown

With a broken connector to the vacuum reservoir you are likely to have been leaking vacuum.
Since a leak in the vacuum circuit could affect any of the above, I would imagined there would have been a perceptible change in the way the car was driving ?

TR7

[dataconn]

My mk5 gt 140 had one of these... it snapped off its mounting bracket early on but didn't seem to make much difference to the car. I asked the garage if it was important and they didn't seem to think so. i think a mechanic leant on it or something.

[k3t4n]

hi

I have this problem on my Audi A4 b5!!! Its a 1.9 tdi....sounds like a daft question, but do you need to replace the entire thing, or can I simply replace the hoses frayed and split? I think I have a vacuum leak here, as I can see the hoses coming out of it are knackered,and the car makes a whooshing sound constantly as I accelerate, so suggesting its a leak.

any ideas how I can go about changing the vacuum lines on this plastic ball? couldnt pull off easily, so just erring on the side of caution. thanks in advance

[Buzzoff]

Hello there,

I replaced the pressure chamber jobbie for the cost of about £16.00 and hay presto I was back on full boost.

As for the pipes feeding to it, yes you can replace them if you want to part with more money however if you can ge away with gently removing the pipe and if there is enough extra hose trim it back and refit.

Please note that the pipe spigot you push the vacume hose back onto is very fragile and can snap with very little pressure.

Cheers

Dan (original thread writer)