Vac pump

Can any help.

I keep loosing vacuum pressure to the servo resulting in hard pedal pressure. After some investigation I traced it back to the were the vac pipe connects to the vac pump, as when I move the vac pipe up & down I can hear a hissing sound coming from the vac pump which I'm sure is not meant to happen.

Does any one know if the pipe connection on the vac pump is meant to be flexible or fixed (circled in the attached picture) as the one on my vac pump moves when you move the pipe.

If its not meant to move can it be fixed or do I need to replace the complete unit.

The engine I have got is a 1.9 TDI (130) engine code AWX.

http://i547.photobucket.com/albums/h...0/vacpump2.jpg

They do move around and hiss a bit, I suspect the leak in the servo hose or in the small 3-mm vac pipe leading off to the EGR/Turbo/manifold flap. Have you had any boost delivery issues?

Hi mate, I have had no boost problems. I've checked all the hoses and they all seem ok. The hissing noise only comes from the hose connection on vac pump.

I will upload a few more pics tonight to try and help with explaining what I mean.

Cheers

Here is a pic that should help explain what I mean -

http://i547.photobucket.com/albums/h...0/DSCF1640.jpg

If I move the vac pipe up & down the connection that sticks out of the vac pump also moves up and down.

I am not 100% sure of its designed to do this or the connection is broken, as this is were I can hear the hissing.

I hope it not broken as a new one around £300.

My mate has got a A4, so I checked his, but his is a newer version and has a different engine code and vac pump.

Hope someone can help, as it can be a bit scary when you press the brake pedal and its rock solid and the car in front has stopped. :1zhelp:

Some movement there is quite normal and a small hiss when moved should not cause a loss of vacuum, after all there is a one way check valve in the pipe that maintains any developed vacuum in the servo and engine vac control system. I would check the system by disconnecting the vacuum pipe from thee pump and using a Mitty Vac hand held vacuum pump, I would test the system for vacuum integrity. Using a vacuum gauge I would then test the pumps output and also use the Mitty Vac to test the pumps sealing. If the system was air tight, I would still bee sceptical about replacing the pump, I have had many A4/A6/Passat 3B servos’ fail due to water ingress from blocked plenum chamber drains. If I came to the conclusion that the loose fitting was the problem, I would replace the pump but I would buy one from somewhere like GSF and I think they are made by LUK. To be honest, if you were loosing that much vacuum, I am sure you would be having turbo boost control and EGR problems so a scan of the ECU would bee a good idea.

Hi mate, thanks for your reply. How much are the hand held vac pumps.

The car had the servo changed a few months ago but still seems to have the problem, I also checked the drains but they were clear.

I don't seem to be losing any boost as it still feels as powerful as it always has. Could it be a combination of the vac pump & the one way check valve.

Would i get the same problem if the master cyclinder was faulty?

Hand held vac pumps vary in price, my kit was about £100 when I bought it a number of years ago. I can’t see that being the master cylinder. The check valves are totally reliable in my experience.

Cheers mate, will get some more checks done to see if I can find the problem.

Thanks again.

Hi
Just come across this post. I have discovered the same apparent problem with a leak from the same port on the vac pump, same model ('02 130 passat), loosing vac pressure and brakes going hard. I am pretty confident that there are no other leaks, none obvious anyway. I have tested the vac pressure with a gauge (engine running) and when this pipe is moved at the joint with the pump it looses about half the vac pressure. I've investigated further and removed the rubber connector pipe to see if there was some damage to the port. I can wiggle the stub about up/down and in/out just about 1mm, the stub will also turn in my fingers. I thought I might be able to tighten it but it just keeps turning in my fingers. Would this indicate the pump is a goner or could it be repaired?
Cheers!

Hi mate, from what you're describing it sounds like it needs replacing.

As a temp repair I used some alaldite for metal until I got a replacement pump, but this only worked for a few days. I got mine for £70 off ebay, BS Motors Ltd in Birmingham. You could try giving them a ring on 0121 328 5222 (this is the phone number off the sales invoice).

I've just seen a few on ebay for around £80, but will depend on which engine code you have got.

Hope this helps.

Hi
Thanks for the info. Did replacing the pump solve your problem or was there more to it, servo, pipes etc? I will start shopping around!

Hi mate, yes it did solve the problem 100%.

It took me about 30mins to change it. But due to the vac pump being a tandem type pump (Brake & Fuel) you will have to make sure that when you connect everything back up that you the prime the fuel side of the pump otherwise it will be very difficult to start.

If you have got a Haynes manual the info on how to change the vac pump is in there.

Hope this help.