Mk4 Polo brake parts replacement

Tzetze

Hi guys. Recently found my polo was losing brake fluid at a rear wheel. Left it into a garage today where they assured me it would be an inexpensive fix (sub €100). They told me I'd get a call from them this afternoon detailing the problem.

So, 6pm comes around and I call them. They tell me that the problem is a 'brake assist module' and replacement part is going to be €80 + a couple of hours labour.

I've just been looking up all brake replacement parts on ebay, and don't see anything remotely like being called a 'brake assist module', and no parts in that kind of price range.

Does what I've been told sound right to you?

Thanks in advance.

Darragh29

Tzetze wrote: »

Hi guys. Recently found my polo was losing brake fluid at a rear wheel. Left it into a garage today where they assured me it would be an inexpensive fix (sub €100). They told me I'd get a call from them this afternoon detailing the problem.

So, 6pm comes around and I call them. They tell me that the problem is a 'brake assist module' and replacement part is going to be €80 + a couple of hours labour.

I've just been looking up all brake replacement parts on ebay, and don't see anything remotely like being called a 'brake assist module', and no parts in that kind of price range.

Does what I've been told sound right to you?

Thanks in advance.

It's also called a brake Servo or brake servo assist module. This component is in the engine compartment and is attached to the master cylinder which is under the brake fluid reservoir. You said though that your car was leaking brake fluid from a rear wheel cylinder??? Is the servo gone as well???

Tzetze

I only assumed a leak around the rear wheel area because there's a stain on my driveway where the rear wheel should be. I could very well be wrong, but if it's just the servo that you mentioned, that leaves me very confused as to what the mess on the driveway is from.

Thanks for the heads up on the servo, I'm clueless about these things, as you've probably guessed. I'll find out for sure when I pick it up tomorrow.

Darragh29

Tzetze wrote: »

I only assumed a leak around the rear wheel area because there's a stain on my driveway where the rear wheel should be. I could very well be wrong, but if it's just the servo that you mentioned, that leaves me very confused as to what the mess on the driveway is from.

Thanks for the heads up on the servo, I'm clueless about these things, as you've probably guessed. I'll find out for sure when I pick it up tomorrow.

Well just make sure that servo or no servo, that your wheel cylinders are replaced if one of them has been leaking! It's convention to change both wheel cylinders if one is leaking and also brake shoes. It's very rare that you would have a brake servo gone, as well as a leaking wheel cylinder.

If your servo was gone, you would notice that braking would be harder to achieve, in that you would have no braking assistance. What exactly was the car in the garage for? Was it just for the leak at the back wheel??? Did you notice any real loss of braking efficiency???

crosstownk

I'd also be inclined to think that it is a wheel cylinder that is leaking. The servo is mounted under the bonnet and even if it was faulty it is unlikely that it would leak fluid.

Is the fluid on your driveway oil based?

Another common fault on certain Polos is a split in the plastic servo vacuum pipe. If this is split/cracked it will demonstrate the same symptoms as a faulty servo. What year is your Polo?

Tzetze

First problem I noticed was yesterday when the brake pedal was travelling almost to the floor before I was getting any braking. I checked the reservoir and it was empty. Filled it up the reservoir last night and left the car into the garage this morning. The reservoir had lost some fluid in the intervening time.

It was only when I left the car in that I was asked if I'd noticed any leakage on the driveway. Had a look when I got home and noticed the stain around the vicinity of the rear wheel. So, it's just my assumption that there was a leak there. When I was leaving the garage, the mechanic was in the process of removing one of the rear wheels, so if there was any leak back there, it would have been spotted.

Would a faulty servo mean loss of brake fluid too?

Edit: it's a '96 1L hatchback.

Darragh29

Tzetze wrote: »

First problem I noticed was yesterday when the brake pedal was travelling almost to the floor before I was getting any braking. I checked the reservoir and it was empty. Filled it up the reservoir last night and left the car into the garage this morning. The reservoir had lost some fluid in the intervening time.

It was only when I left the car in that I was asked if I'd noticed any leakage on the driveway. Had a look when I got home and noticed the stain around the vicinity of the rear wheel. So, it's just my assumption that there was a leak there. When I was leaving the garage, the mechanic was in the process of removing one of the rear wheels, so if there was any leak back there, it would have been spotted.

Would a faulty servo mean loss of brake fluid too?

Edit: it's a '96 1L hatchback.

It would but normally servo's leak inside the component causing the servo to fill up internally with brake fluid. There's a fair bit of room inside there to hold a good deal of brake fluid. Maybe it was leaking and the garage decided to change it.

crosstownk

Right - if you're leaking fluid to the extent that the reservoir is empty then you have a serious problem and the car is dangerous to drive - very high risk of serious brake failure.

Ask the garage to show you the faulty component, point out the location of the leak and explain to you (like you were a two year old) why it is need of replacing. Also ask them to clarify what this 'brake assist module' is and why it is the cause of your leak and if it's not the cause of the leak then why they have come to the conclusion that it is faulty.

I don't think you need worry about the split vacuum hose as it usually happened on later models, but no harm to get them to visually inspect it.

Tzetze

Thanks for the info guys, you've both been a great help. Will definitely ask those questions tomorrow, Crosstownk.

cabbott

there is also a part underneath the car near the back left wheel, its called brake equalizer valve it increases brake effect to the back wheels when the car is loaded, its on the golfs anyway, possibly on the polo aswell,i forget, these sometimes leak.
if you have a badly leaking wheel cylinder, brake fluid will have got onto the brake shoes and will have to be replaced. this takes 2 hours to replace shoes and cylinders.

crosstownk

cabbott wrote: »

if you have a badly leaking wheel cylinder, brake fluid will have got onto the brake shoes and will have to be replaced. this takes 2 hours to replace shoes and cylinders.

Yep - but if they are the genuine shoes they can be relined. Genuine replacement shoes will cost quite a bit. But I'd imagine that as the Polo is a 1996 that spurious shoes will be fitted which is probably the most economical option.

Darragh29

crosstownk wrote: »

Yep - but if they are the genuine shoes they can be relined. Genuine replacement shoes will cost quite a bit. But I'd imagine that as the Polo is a 1996 that spurious shoes will be fitted which is probably the most economical option.

Jasus crosstownk, relined brake shoes, that's goin back a long time! I know we're in recession but there shouldn't be any prob getting a decent set of brake shoes!

crosstownk

Darragh29 wrote: »

Jasus crosstownk, relined brake shoes, that's goin back a long time! I know we're in recession but there shouldn't be any prob getting a decent set of brake shoes!

I know - I'm showing my age

But you can still get linings for a 96 Polo - and for most VWs with shoes of that era. A set of linings is quite cheap - usually cheaper than a set of spurious shoes but the labour usually makes it prohibitive. Genuine shoes are probably in excess of €50 per shoe.

Item no. 29 (part number 191 698 051) in the illustration below is the lining kit....

@ Tzetze - item 6 is the rear wheel cylinder.



Item 1 in the following illustration is the brake servo unit and item 10 is the brake pressure regulator that cabbott reffered to in an earlier post. It might give you an idea of what the parts look like - so if the garage show them to you, you might make the connection.

Mr.David

If you are worried about being done, request that any parts that are replaced, the old ones get left in the boot.:)