Guide – The best way I’ve discovered to bleed a stubborn hydraulic clutch.

You all know how it is – you spend precious time and money bleeding a clutch system only to find that you just can’t rid it of that stubborn bubble of air. This is an unfortunate pain of hydraulic clutches and often results in clutch drag, shuddery starts and crunchy gear changes. Even more difficult is the concentric slave cylinder on the Mk1 vRS that does not permit you to compress its piston without removing the transmission. I believe I have found the best way for the DIYer to bleed the clutch system alongside the braking system, so I thought I would roll up my sleeves and contribute something to the cause

Parts and equipment required –

1 litre DOT4 brake fluid

Jack, jack stands, wheel removing tools

Bleeder monkey/hobo/slave etc.

Open ended spanners

Short section of 5mm internal diameter pvc plastic tubing (30cm or so)

Long section of 5mm internal diameter pvc plastic tubing (2m or so)

Slim cable ties

Pressure bleeder system e.g. Gunzons eezibleed (optional)

Part 1 – Raise the car, support it on axle stands and remove the wheels. Two axle stands at the front are sufficient since the rear brakes can be bled without removing the rear wheels.

Part 2 – Bleed the entire brakes and clutch system in the conventional way either using a pressure bleeder, or use your hobo to pump the brake and clutch pedals while you open the bleed nipples. Flush the system with 1 litre of fresh fluid and drain into an old plastic bottle using the short section of tubing. Dispose of old brake fluid responsibly. Bleed the system in the following order – clutch, front left, front right, rear left, rear right. Bleeding the entire system is important for the next step. When the system is completely bled, check the level of fluid in the master cylinder and replace the cap.

Part 3 – Connect a long section of plastic tubing between the bleed nipple on the front left brake calliper and the bleed nipple on the clutch slave cylinder. Tightly secure the tube to the nipples using slim cable ties. Open the clutch bleed nipple. Now for the important part – we are going to use the forwards pressure in the braking system to reverse bleed the clutch system. Since the brakes and clutch share the same fluid reservoir the fluid will simply circulate without a change in level, but will force the air bubbles out of the clutch system in the preferential uphill direction. So follow these steps-

1.) Open the brake nipple.

2.) Get your hobo to GENTLY press the brake pedal to the floor.

3.) Close the brake nipple.

4.) Get your hobo to release the brake pedal.

5.) Follow steps 1-4 ten times.

6.) Close the clutch bleed nipple. Get you hobo to forcefully pump the clutch pedal in and out. Open the clutch bleed nipple again.

7.) Follow steps 1-6 three times.

8.) All done. Make sure all bleed nipples are closed. Carefully remove the long tubing and drain the fluid in the tube back into the master cylinder.

Part 4 – Test the functionality of the brake and clutch pedals. Replace the wheels and lower the car. Go for a drive and be amazed by the improvements.

Summary – Hydraulic clutches can be a pleasure to use and are remarkably direct and smooth. However problems of air bubbles in the system can cause an enormous amount of pain for the operator. This method uses the forwards pressure of the braking system to reverse bleed the clutch system. It is important to first bleed the entire system with fresh fluid therefore avoiding the problems of dirt and contaminants entering the clutch system. This method assumes that air has entered the clutch system through no serious fault of the components. If air continues to be a problem after performing these steps then it may be neccessary to replace various components.

Enjoy

Edited 28 May, 201214 yr by piggoy

That's a fantastic idea I will defiantly be trying this one, I know I have air in my clutch system,

Thank you

Matt

I do wonder if this is all that my car is suffering from. I may have to attempt this one. Where did you get the tubing from?

I do wonder if this is all that my car is suffering from. I may have to attempt this one. Where did you get the tubing from?

It just standard PVC tubing on a roll from Homebase. I can't remember exactly the internal diameter but it was a very tight fit over the bleed nipples - it needs to be because the line is quite highly pressurised, that's why the cable ties are also neccessary.

Ah... maybe this is the cause to my stiff/cruntchy gear changes.

When I did by brakes I bled the clutch but didn't know about the bleed nipple on the master cylinder. I only bled from the pipe that goes into the gearbok near the shift linkage.

Phil

Ah... maybe this is the cause to my stiff/cruntchy gear changes.

When I did by brakes I bled the clutch but didn't know about the bleed nipple on the master cylinder. I only bled from the pipe that goes into the gearbok near the shift linkage.

Phil

#

There is only one bleed nipple on the clutch and that is in the location you mention (next to the gear shift linkage). The method is to reverse bleed the clutch by forcing fluid from the brake caliper into the clutch bleed nipple.

Ah right. I have obviously got muddled reading some other things on the internet.

When I first did the brakes I didn't know the clutch shared the same fluid as the brakes and so didn't do it. I did them all again including the clutch but might give it another go and then try your method of reverse bleeding.

BTW. You mention either using a pressure bleeder or pumping the brakes. As far as I understood this shouldn't be done on VAG cars and only a pressure bleeder should be used.

Ah right. I have obviously got muddled reading some other things on the internet.

When I first did the brakes I didn't know the clutch shared the same fluid as the brakes and so didn't do it. I did them all again including the clutch but might give it another go and then try your method of reverse bleeding.

BTW. You mention either using a pressure bleeder or pumping the brakes. As far as I understood this shouldn't be done on VAG cars and only a pressure bleeder should be used.

I'm not sure about this. I only ever use a pressure bleeder when bleeding the system (part 2) because it's a heck of a lot easier. But part 3 can only be done using an assistant, a pressure bleeder will not work for this. I don't see why the traditional "two-man" method can't be used for VAG cars, Haynes says it's fine, but then again I'm no expert.

I'm not sure about this. I only ever use a pressure bleeder when bleeding the system (part 2) because it's a heck of a lot easier. But part 3 can only be done using an assistant, a pressure bleeder will not work for this. I don't see why the traditional "two-man" method can't be used for VAG cars, Haynes says it's fine, but then again I'm no expert.

I've heard some horror stories of ... a ... brake cylinder? master cylinder? going past where it should do and destroying a seal or something, when bleeding it the old fashioned way. Seems like you got away with it okay though!

I'm hopefully going to pick up some tubing and a pressure bleeder and the father will help me do this over the weekend. I have a lot of difficulty getting it in to reverse, out of first, and it kinda seems like the clutch is still engaged a bit in first *sometimes*. I'm told it's a quirk of the clutch setup (Helix), but.... thinking about it.... it may have started shortly after a brake fluid change by a garage :(

I've heard some horror stories of ... a ... brake cylinder? master cylinder? going past where it should do and destroying a seal or something, when bleeding it the old fashioned way. Seems like you got away with it okay though!

I'm hopefully going to pick up some tubing and a pressure bleeder and the father will help me do this over the weekend. I have a lot of difficulty getting it in to reverse, out of first, and it kinda seems like the clutch is still engaged a bit in first *sometimes*. I'm told it's a quirk of the clutch setup (Helix), but.... thinking about it.... it may have started shortly after a brake fluid change by a garage :(

I really hope this works for you. I had exactly the same problems as you describe after bleeding my brakes and clutch for the first time about a year ago. I also initially thought it was problems with my clutch, gearbox synchros, DMF etc, but the onset of the symptoms straight after the first bleed a year ago was too much of a coincidence - I knew it must be something to do with the clutch dragging due to it not disengaging properly. It took me ages to devise a solution, but when I finally did the results were amazing. My car is so much more pleasurable to drive! I no longer have any worries when doing 'sporty' quick shift gear changes. No more granny shifting and double declutching to avoid the crunch

I really hope this works for you. I had exactly the same problems as you describe after bleeding my brakes and clutch for the first time about a year ago. I also initially thought it was problems with my clutch, gearbox synchros, DMF etc, but the onset of the symptoms straight after the first bleed a year ago was too much of a coincidence - I knew it must be something to do with the clutch dragging due to it not disengaging properly. It took me ages to devise a solution, but when I finally did the results were amazing. My car is so much more pleasurable to drive! I no longer have any worries when doing 'sporty' quick shift gear changes. No more granny shifting and double declutching to avoid the crunch

I hope too. Sounds promising, and I thank you for posting such a detailed potential solution I will let you know how I get on.

Mine's not that bad. It's mostly just 1st and reverse - I swear a couple of times mashing on the brakes has free'd up the clutch / gear before, but I am never 100% sure!

If it stops my gear difficulties I will be one happy chappy! Hopefully it won't have damaged the clutch / gearbox too badly :(

I hope too. Sounds promising, and I thank you for posting such a detailed potential solution I will let you know how I get on.

Mine's not that bad. It's mostly just 1st and reverse - I swear a couple of times mashing on the brakes has free'd up the clutch / gear before, but I am never 100% sure!

If it stops my gear difficulties I will be one happy chappy! Hopefully it won't have damaged the clutch / gearbox too badly :(

No worries. Just one more tip which I didn't explain in my guide - you need to fill the tubing with fluid from the brake caliper before fitting it to the clutch nipple, that way you minimise the amount of air you will pump into clutch nipple before the fluid starts to circulate. And just pay attention to the fixing of the tube to the nipples - it's all too easy for the tubing to pop off and brake fluid to go spraying everywhere if they are not fixed tightly or the brake pedal is pushed too heavily. Best of luck

Edited 25 May, 201214 yr by piggoy

5mm or 3mm hose? :-)

5mm or 3mm hose? :-)

No one knows? In the Eezibleed kit there's two pipe sizes - 5.4mm and 3.5mm. Just need to know which so I can get extra length

For others, it's the 5.4mm tubing that you need - 5mm stuff from B&Q worked fine. The Father suggested bleeding normally first, as he was weary of reverse bleeding (he was taught not to do it, as it can bugger seals up apparently?).

So, we just bled the clutch. It was pretty straight forward. I pushed on the clutch 6 times, then on the last one held it to the floor whilst he tightened. On the first bleed apparently quite a lot of air came out! The fluid looked a bit hazy too. We repeated this a few times and put things back together. So far so good, but i'll give it a few days

One thing we also noticed, is that the slave cylinder seems a bit loose.... it wiggles about a bit! I have a bit of 'slack' on my clutch pedal, where nothing seems to happen when I push and it feels quite loose on the pedal - it seems that when I get to the end of this on the pedal, the slave cylinder tightens up. Is this normal? If that makes any sense at all?

For others, it's the 5.4mm tubing that you need - 5mm stuff from B&Q worked fine. The Father suggested bleeding normally first, as he was weary of reverse bleeding (he was taught not to do it, as it can bugger seals up apparently?).

So, we just bled the clutch. It was pretty straight forward. I pushed on the clutch 6 times, then on the last one held it to the floor whilst he tightened. On the first bleed apparently quite a lot of air came out! The fluid looked a bit hazy too. We repeated this a few times and put things back together. So far so good, but i'll give it a few days

One thing we also noticed, is that the slave cylinder seems a bit loose.... it wiggles about a bit! I have a bit of 'slack' on my clutch pedal, where nothing seems to happen when I push and it feels quite loose on the pedal - it seems that when I get to the end of this on the pedal, the slave cylinder tightens up. Is this normal? If that makes any sense at all?

I've been told the known issues of reverse bleeding relate to dirt and impurities in old fluid damaging and contaminating seals - hence forward bleeding the entire system first with fresh fluid before attempting any reverse bleeding.

Did you try the reverse bleed of the clutch using the brakes or did a forward bleed manage to expel the air?

I've been told the known issues of reverse bleeding relate to dirt and impurities in old fluid damaging and contaminating seals - hence forward bleeding the entire system first with fresh fluid before attempting any reverse bleeding.

Did you try the reverse bleed of the clutch using the brakes or did a forward bleed manage to expel the air?

A normal bleed got quite a lot of air out apparently (I was on the clutch, so couldn't actually see). We did it a few times. After the first go, no more air came out. It seems to be behaving much better so far - I'm waiting for the problems to slowly return though!!

It seems to be behaving better though, so hopefully it's just air in the system that can be completely removed (eventually!!).

A normal bleed got quite a lot of air out apparently (I was on the clutch, so couldn't actually see). We did it a few times. After the first go, no more air came out. It seems to be behaving much better so far - I'm waiting for the problems to slowly return though!!

It seems to be behaving better though, so hopefully it's just air in the system that can be completely removed (eventually!!).

And what do you know, it's gradually returned over a few days of use! I'm sure it must just be stuck air. I'll try and convince father to help me do a reverse bleed at the weekend - I just want it over and done with!! It was nice to drive without it sticking in 1st / hard reverse :(

Just sumbled upon this whilst researching some more:

http://forums.vwvortex.com/showthread.php?2970528-I-think-I-need-a-new-clutch-master-cylinder-mad&p=34591247&viewfull=1#post34591247

and

http://forums.vwvortex.com/showthread.php?4376420-How-to-bleed-your-02M-clutch-slave-cylinder-the-effective-way.

Sounds scary and I would rather not attempt that. Does the reverse bleed achieve the same thing? Specifically in the first link:

This creates a problem because the slave must be bench bled or in a retracted state when installed. If it is installed in a neutral state, with air in the cylinder, then no matter how well you bleed the system, you will still have air in the slave, because when you bleed the system, you are bleeding the master cylinder and the line, not the slave, since it is on the other side of the bleeder valve.

It sounds like connecting a hose from the clutch bleed valve to a caliper still wouldn't be able to get any air out of the slave cylinder?

Just sumbled upon this whilst researching some more:

http://forums.vwvort...=1#post34591247

and

http://forums.vwvort...-effective-way.

Sounds scary and I would rather not attempt that. Does the reverse bleed achieve the same thing? Specifically in the first link:

It sounds like connecting a hose from the clutch bleed valve to a caliper still wouldn't be able to get any air out of the slave cylinder?

I don't agree with that post on VWVortex. It doesn't make sense for two reasons. If the slave cylinder is designed in the way the writer describes in that post 1.) The concentric slave cylinder would never be able to be bled properly and it will have air trapped in it from the moment the car leaves the factory, 2.) old fluid, dirt and contaminants would never be able to be removed from the slave cylinder during a bleed, it would contain the same dirty fluid for it's entire life!

I've been reading this thread with interest.

I like the idea of a reverse bleed, but at the moment I can't seem to get my head around how/why it could purge anymore air out of the system than a regular clutch bleed. Worth a try I guess - so long as no damage can be induced by reversing the flow of clutch fluid at highish pressure.

Anyway, with regards to the slave cylinder, yes it sits inside the bell, and the bleed valve sits way before the slave cylinder, so no matter how much flushing you do, you'll never (from what I can see) be able to flush the old oil from inside the bell housing.

Some people have suggested to bleed the slave cylinder by using thin pipe inserted into a disconnected bleed valve, and pump oil out that way. Seems like a (abit risky) solution, but other than this method, I can't see any other way. A reverse bleed wouldn't do anything to clear the old oil from the Slave cylinder.

With regards to the comment about factory bleeding + air, this is a valid point. Not sure how it's done, and surely some sort of method would be used when the slave cylinder is replaced when a new clutch is fitted.

Maybe someone has access to VAG technician manual for the proper vag process?