Brake pedal sucking noise

Tractor Dave

Tractor Dave

Member
So, another one has arrived!
After seeing my tdi 90 I recently purchased for my daughter, my brother in law has bought one for his daughter.
And, being the one in the family with mechanical knowledge, it's arrived at mine for a full service and once over.
There is unfortunately no service history with this car. The cambelt looks worn. So, it will be having a cambelt change and new oils and fluids/filters. Rear shocks are also past their best and tie rod ends perished.

Whilst driving the car into the garage, I noticed a sucking noise from the area of the brake pedal each time the brake was used. I looked up here and found a few threads indicating this is a master cylinder issue. Before I strip it out and replace, is there a vac pipe or anything else that might be the culprit? The brakes do feel a bit spongy but I haven't changed the fluid yet.

219e2bb5be2c479ab32d5610d04008a9.jpg
 
More likely to be that the brake servo is leaking in some way. You will find that it is connected to the vac pump.

RAB
 
Tractor Dave said:
So, another one has arrived!
After seeing my tdi 90 I recently purchased for my daughter, my brother in law has bought one for his daughter.
And, being the one in the family with mechanical knowledge, it's arrived at mine for a full service and once over.
There is unfortunately no service history with this car. The cambelt looks worn. So, it will be having a cambelt change and new oils and fluids/filters. Rear shocks are also past their best and tie rod ends perished.

Whilst driving the car into the garage, I noticed a sucking noise from the area of the brake pedal each time the brake was used. I looked up here and found a few threads indicating this is a master cylinder issue. Before I strip it out and replace, is there a vac pipe or anything else that might be the culprit? The brakes do feel a bit spongy but I haven't changed the fluid yet.

219e2bb5be2c479ab32d5610d04008a9.jpg
Click to expand...
Oooooohhh garage envy!

Sent from my SM-N960F using Tapatalk
 
Tractor Dave said:
So, another one has arrived!
After seeing my tdi 90 I recently purchased for my daughter, my brother in law has bought one for his daughter.
And, being the one in the family with mechanical knowledge, it's arrived at mine for a full service and once over.
There is unfortunately no service history with this car. The cambelt looks worn. So, it will be having a cambelt change and new oils and fluids/filters. Rear shocks are also past their best and tie rod ends perished.

Whilst driving the car into the garage, I noticed a sucking noise from the area of the brake pedal each time the brake was used. I looked up here and found a few threads indicating this is a master cylinder issue. Before I strip it out and replace, is there a vac pipe or anything else that might be the culprit? The brakes do feel a bit spongy but I haven't changed the fluid yet.

219e2bb5be2c479ab32d5610d04008a9.jpg
Click to expand...
Can’t answer the question but is that lift a 3 phase? If not what brand is it? My new workshop is big enough for one so I might take the plunge.
 
Check the hose coming off the rear of the tandem pump, this is the vacuum supply pipe. This pipe could be porous or loose on the tandem ( the fitting of the tandem itself must be tight and not able to rotate or rattle. If this is loose remove the hose from the fitting and glue the fitting in with 24 hour epoxy making sure it is fully seated and can not move while drying. Refit the vac hose and test. The epoxy should not be looked as a permanent fix. That would be a tandem pump replacement.
If the tandem was fine and the hose is also fine then check the connection onto the servo for leaks. If still OK then suspect internal issue with the diaphragm in the servo so a replacement would be needed.
 
There is one other part you could check. The bellows that fit around the rod on the pedal, if they are split or loose they could also be the source of the noise. I do not know if the bellows are available separately or part of the servo.
 
audifan said:
There is one other part you could check. The bellows that fit around the rod on the pedal, if they are split or loose they could also be the source of the noise. I do not know if the bellows are available separately or part of the servo.
Click to expand...
Evening Graham,

I have a Servo in the garage so will check to see if the bellows look to be replaceable. Give me 30 minutes.

Kind regards,

Tom
 
Evening Dave,

Just seen your PM and Will respond shortly Sir.

The brake servo I have here belongs to @Sarge, who sent it me some time ago which turned out to be an incorrect part from my 1.4 Petrol BBY A2.

Kind regards,

Tom
 
@2work Tom as far as I can see there is only 2 different part numbers for the brake servo, one for a MK20 and the other for a MK60 ABS change over date of late 2001. So would have thought BBY will use the MK60?
 
Ok, looking for a good servo for a 2003 75 tdi part number 8z2614105b
Unfortunately, the one Tom has (from Sarge) is slightly different.
Got the old one out. Not too difficult after reading up here. What a great forum!
 
Thanks Rab. I saw that last night and have sent the seller a question about the seal. You can’t see it in the picture.


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It's the diaphragm that's the critical component. I'm sure that you could find somewhere to recondition your existing servo:


Have you checked for a leak between the servo and the tandem pump?

RAB
 
Has anyone got item 24 on this diagram? It's the plastic clip that the servo rod ball end fits into. I have ordered one on ebay but it doesn't look like it will fit. Audi say it's nla. Please ignore the fact that 23 is highlighted.
1620828855082.png
 
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