Volkswagen Golf Mark 4 - Brake bleeding problem.

mobfromcork

I offered to help a friend change the pads and discs and one caliper on his Golf Mark 4 yesterday but I ran into a few problems on the way. I've done this job on a few cars before with no major difficulties but I stupidly managed to let the level on the master cylinder drop (due to fluid escaping from the banjo bolt on the driver's side rear caliper which I hadn't sealed properly and left to drip overnight, ending up with pretty much the entire contents of the brake fluid system on the ground). I could have kicked myself this morning when I saw it!

So this morning I fitted the new caliper. I bled the master cylinder one nipple at a time and then started with the rear passenger, rear driver, passenger and driver. With the car turned off the brake pedal seemed to have good pressure but when I started the car, I was able to depress the pedal almost to the floor and the brakes were obviously still very suspect. I was working alone today with one of those one-man bleeding kits. No visible leaks from anywhere.

I'm going to tackle it again tomorrow (hopefully with a little help). I don't have the manual for this car. Has anyone encountered this before? Is my sequence of bleeding wrong? Any tips or information would be greatly appreciated.

Thanks

Mark

muckeyw

Are u a mechanic ????this is a job for us qualified mechanics brake systems save people's lifes if u were just changing pads why did u open the brake fluid pipe u shouldn't of seriously we send 4 years in collage for this like.hears a tip blead the brakes with engine running as the master cylinder also works on vacuum wen the engine is running

mobfromcork

I'm not a mechanic MuckeyW but have done the vast majority of my own servicing work on my motorbikes for the last 12 years and cars for approx 6 years so I've a reasonable amount of knowledge about how some of the main servicing jobs are done.

It was a stupid mistake to leave the master cylinder run so low but one I won't make again.

I opened the brake fluid pipe to connect up the new brake caliper, not to change the pads.

Thanks for your tip to bleed with the engine running. That should save mea bit of time this morning I hope.

Mark

Slidey

There is a bleed nipple on the side of the master cylinder.

You need to bleed it there first.

Nissan doctor

muckeyw wrote: »

Are u a mechanic ????this is a job for us qualified mechanics brake systems save people's lifes if u were just changing pads why did u open the brake fluid pipe u shouldn't of seriously we send 4 years in collage for this like.hears a tip blead the brakes with engine running as the master cylinder also works on vacuum wen the engine is running

Are you a mechanic?? The master cylinder does not run on any vacum. Thats the servo your thinking of. Brakes should be bled with the engine off so you have direct pedal pressure.


@OP, There are 2 bleed nipples on most VAG master cylinders, did you bleed both? Does the car have ABS/ESP? I so then the brake bleed kit your using may no be able to draw trapped air from the ABS unit, you need someone to pump the pedal.

mobfromcork

Thanks Slidey,

There are two nipples on the side of the master cylinder and I bled both of them yesterday before starting the caliper bleeding. I went and bought one of the Gunson Eezibleed tools this morning http://www.gunson.co.uk/item.aspx?cat=674&item=1818 which use air pressure to pump new fluid in and expel old fluid and air so I'm going to try that and see how I get on. It might save a lot of pedal pumping.

I'll post up later with any further updates.

Mark

mobfromcork

Thanks Nissan Doc,

I've got my brother to give me a hand later on. I'll start by bleeding both the nipples on the master cylinder again and then I'll go through the instructions on the EeziBleed tool. It seems straightforward enough but it'll be good to have another set of hands to help me out. The car does has ABS so hopefully I'll do a combination of the tool and the pump to try and get the air out.

spiggotpaddy

yeah it will be easier with a mate, just take your time and it will bleed out.
you may want to check the clutch, if you have let air into the whole system,
anyway you've got your new easybleed tool if the clutch is spongey.

mobfromcork

Job done. Thanks for the replies.
The Eezi-Bleed makes it so much easier. It was 24 euro well spent as I'll use it on the motorbikes as well. It's still easier having 2 people even though you could probably do it alone. It took us about 30 mins for the master cylinder and the 4 calipers.

The problem ended up being a bit of air still being stuck in the master cylinder. There were also small bubbles in the rear passenger caliper but all sorted now.

Thanks again.

Mark

mickdw

muckeyw wrote: »

Are u a mechanic ????this is a job for us qualified mechanics brake systems save people's lifes if u were just changing pads why did u open the brake fluid pipe u shouldn't of seriously we send 4 years in collage for this like.hears a tip blead the brakes with engine running as the master cylinder also works on vacuum wen the engine is running

4 years in college! Glad I ddnt go to that college. The spelling is bad. This is no big problem for a mechanic but when your mechanical knowledge appears to be even worse, its kinda scary.