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1.8 TDCI clutch bleed / flush methods


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The Haynes manual explains the clutch bleed / flush method as alternating between opening / closing the bleed valve on top on the transmission and depressing / releasing the clutch pedal. For this method two people are needed.

But can the 1.8 TDCI clutch be bled using the gravity method (without a second person)? And, if it is workable, what is the location of the valve to be opened using the gravity method?

Hope members will share their experiences.

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Isn't the bleed valve part of the slave cylinder assy on these?  If not, it must be fitted in the pipework just before the slave connection.

Gravity bleeding won't work properly.  Ideally I would recommend a vacuum bleeder to suck the fluid through.  But you can still do it with one person using a One-Man Bleeder pipe which includes a one-way valve.  That means fluid cannot be sucked back in when the pedal is released so there's no need for a second person opening and closing the nipple with each pedal press.

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Hi Tom, yes there is a bleeder valve as part of the CSC unit, but I was hoping there might be an old school valve nearer the front of the car and lower down to allow gravity bleed. Do you know? 1.8 TDCI is an old enough engine to have one. Basically I would like to flush.

Because the gearbox is now off, I want to put in new clutch fluid so the new CSC and clutch start their lives with new clean fluid. In retrospect should have done that (using clutch pedal and bleeder valve alternately)before I started dismantling anything, but live and learn! 

Pressure bleeding is not recommended for the clutch I have read (seems fine for brakes), so basically the main aim is to do a very 'gentle' flush as one man without depressing pedals.

I am thinking ... I have a 1.5 litre syringe. What about sucking out the reservoir with it, wiping it clean and topping up with new fluid? If necessary I then repeat to at least improve the condition of the fluid which has been there some years. Would that work?

In case of use, I have a new clutch line pipe if needed (but not the hose it plugs into), so this:

https://www.ebay.co.uk/itm/393457867211?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=7k6w-3wmqzu&sssrc=4429486&ssuid=yVFafxpISdO&var=&widget_ver=artemis&media=COPY

NOT this:

 https://www.ebay.co.uk/itm/235260723737?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=ihsusevvrhs&sssrc=4429486&ssuid=yVFafxpISdO&var=&widget_ver=artemis&media=COPY

 

 

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There isn't a second bleed nipple for the clutch pipe as far as I know.  Although it's an old engine, it's the gearbox & chassis that really decide the clutch system.

As the CSC is removed, you can just pump the clutch a few times to force all of the fluid out of that open pipe.  Then fill it with fresh fluid and bleed it through when you fit the new CSC.

Perhaps I'm missing something but it feels like you're overcomplicating this.  If you're concerned about the master cylinder seals, you could disconnect the pipe from that end as well then tip it up on end to gravity drain.  But I'd be more concerned about disturbing the pipe connection than damaging the MC.  As you're going to all the effort of a major refresh, you could replace the MC at the same time.

Don't forget the reservoir is shared for both clutch & brakes.  So make sure not to touch the brake pedal while the reservoir is low, otherwise you'll suck air into the brakes and end up with a much bigger job.

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Tom, thanks for this. Yes, probably am overthinking, hence your guidance is valued.

So, with gearbox off (and thereby CSC removed from the car clutch system) I can just open the bleeder valve halfway and pump the clutch a few times to eject the fluid? So just do it all myself? Do I not need to alternate opening and tightening of the bleeder valve with depressing and releasing the clutch pedal (as per Haynes manual) which is two people?

Also to do this do I need to put the pipe from the master cylinder back in (next to the bleed valve)? Right now it is disconnected and end covered.

I think you are right about leaving the MC pipe connection undisturbed and for that reason I will also leave the MC unchanged (it's Ford original and only 60k miles). If I have to do MC later, then I'll renew the hose too. New fluid should help preserve the seals anyway. (Also present work more than enough for now, will detail later).

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The CSC pipe should be open at the gearbox end without the CSC connected.  If there is a bleed nipple on the pipe before the CSC then you would need to open that.  Then just place a container under it, or connect a bit of spare pipe to prevent any mess.

Yes, you just need to keep pressing and releasing the pedal to push the fluid through.  The reason for closing off the valve each time when bleeding is to prevent old fluid and air bubbles getting sucked back up the pipe from the open nipple.  But that syphon effect won't happen when being drained.  You will need to use your hand to lift the pedal each time as it will just stay on the floor when pressed under these conditions.

I'm slightly confused by which pipe has been removed.  I thought it was the MC to CSC pipe that's being drained?  If so, it doesn't need to be put back onto the CSC, just leave it open and place into a container.  If you reconnect it to the CSC then you'll be putting dirty fluid through the CSC.

It's worth noting this should be done as close as possible to fitting the new CSC & refilling the fluid.  Don't want to leave the pipework exposed to air and damp in the meantime.  Better to leave it full of old fluid until the last minute.

You will also need a one way valve or a vacuum/pressure bleeder in order to bleed the system with fresh fluid.  It is possible to do with only one person, but you need that one way valve if you're not going to vac or pressure bleed.  This is what I mean by a one-way valve, there are a few options around £10 each.  Much cheaper than hiring an assistant!  Vizibleed Brake & Clutch Bleeding Kit with Container & Retaining Strap,... | eBay

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Thank you very much Tom, you make a good point about not leaving the clutch lines empty (especially in damp weather). I will do the flush and refill in one go, and only directly before fitting the gearbox (with new clutch and CSC).

Drawing on your guidance, this is what I plan (let me know if it makes sense).

Gearbox is off, so CSC off. There are only two holes. One is the bleeder valve the second is where the tube from MC to CSC plugs in.

So I will connect some tubing to the bleeder valve to guide the clutch fluid being pushed out of the system into a container.

And also lower the MC to CSC pipe into a container to drain.

Attach one-way valve product (1 man bleeder)to bleeder valve, with container to catch purged fluid. Open the bleeder valve halfway and then pump the clutch pedal until the old fluid has been purged, and new fluid coming through. All the while ensure that the reservoir is topped up as I go. Then close the bleeder valve.

Fit gearbox, then bleed clutch system as above, to purge any last air bubbles (adding the new CSC since the earlier flush will add air to the system, until it is replaced with new fluid).

Does this make sense?

I have a load of Ford fluid so not worried about saving a litre here or there, just to do a thorough job.

 

 

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That generally makes sense.  Though the bleed valve part is still confusing me.  While the open pipe is in a container, there is no need to open the bleed valve or connect anything to it.  The pipe end is already open so fluid should come out of there.  If you can post a picture of your current setup, that might help confirm either way.  It's been a while since I've seen one of these and may be confusing it with another Mk2 gearbox type now.

Personally I wouldn't run new fluid through the system.  I get that you're not fussed about the cost but it still seems like a waste of time and resources to me.  There shouldn't be anything stuck in the pipework to flush out (unlike coolant radiators and matrices for example) so I would just drain out the old fluid, then fill with new at the same time as bleeding.  But that is entirely your decision of course.  Ultimately as long as it ends up filled with fresh fluid and no air in the system after the CSC is refitted that's the best possible end result.

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Reason for the flush and renew clutch fluid before installing gearbox and new CSC, and then a bleed and top up afterwards is because a) I don't want to depress the new CSC too much when it is dry and b) I want any fluid that goes to it to be new fluid. I don't see how I can achieve both without doing the above two steps (maybe a bit OCD perhaps).

I will take a picture of the two holes (bleeder valve and pressure pipe from MC to CSC) when it's dry. Reverting.

Meantime will order a 1 man bleeder so it's on standby as cheap enough. Do you recommend the one you sent me in the link?

 

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Yes, I have the same Vizibleed kit as the one in that link.  It may be cheaper from other places though, that's just the first one that came up on eBay.

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Morning Tom, still wet so not lifting the cover and doing some research. These two articles may be of interest to members installing a new CSC or doing clutch work.

https://pmmonline.co.uk/technical/best-practice-clutch-or-concentric-slave-cylinder-installation/#:~:text=Never pressurise the CSC until it is fully installed in the gearbox.&text=Flush old hydraulic fluid from,seals may swell or disintegrate.

https://pmmonline.co.uk/technical/installation-tips-for-csc-replacement/

My takeaway:

A flush prior to fitting and a bleed after fitting is recommended. The flush method doesn't matter so much.

After CSC / gearbox installation, then use the pedal judiciously, press once and then wait a bit for the vacuum / hydraulics system to do its thing and trigger the flow before considering pressing again. Repeated pressing of the peddle before the CSC has been fully primed with fluid is likely to cause damage to it.

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OK, so too damp to lift the bonnet for photos so, thinking about the architecture of the clutch system I thought I would take a look at the old CSC I took off. I attach a couple of photos of front and back. The whole story is there ... I think (still feeling my way). Experts forgive me if I tell you what you know, or balls it up (in which case correct me).

There is no entry / exit hole at all on the back. On the front there are is the bleeder nipple and the hole for the thin solid pressure pipe from the MC to feed the CSC. This must mean the CSC is the end of the hydraulic system, fed clutch fluid through the pressure pipe from the MC as / when called on by pressing the clutch pedal.  The fluid does not pass beyond the CSC and remains within the clutch system. As unless the bleeder open for bleeding there is no exit for the fluid. 

Now, how about flushing the clutch system without the CSC (as gearbox removed)? I am not sure I can use the clutch pedal as there is now bleeder valve (it is incorporated in the CSC, and there is no CSC as there is no gearbox). So I think the only way is to suck the fluid out either side of the MC, from the reservoir and its outlet on the one side, and from the solid pressure pipe that runs between the MC and the CSC.

Assuming the MC seals are holding OK (no reason to doubt) it is then just a matter of filling up with new fluid the reservoir and hose to the MC. I can't fill the solid pressure pipe but that will only be a small amount of fluid anyway.

Then install the gearbox with CSC, plug in the solid pressure pipe to the CSC from the MC., top up the reservoir (as the pressure pipe and CSC will need to have the air in them replaced with fluid) and do a carefully regular bleed with clutch pedal and bleeder valve (now CSC in place) as per the PMM article link above.

Am I wrong? 

IMG_20240923_185849097_HDR.jpg

IMG_20240923_185832323.jpg

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Yes, that's correct, it really is a very simple system.

Just one part that I'll pick up on though.  The hard pipe is open at the end right now.  When you press the pedal, fluid will come out of that open end.  The bleed nipple is irrelevant while the CSC is disconnected.  Just place a container under that open end and press the pedal slowly.

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Thanks Tom, for that correction (I suppose it's logical too but still getting all this into my head). Yes, need to press slowly to make the most of the purging effect of the pedal ...

After the purge, I then just fill up the reservoir (which will run to the MC) until bubbles stop ...

I then install the gearbox with CSC, plug in the hard pipe to the CSC from the MC. These two will add capacity (i.e. new air) to the system, so it is just a matter of checking / topping up the reservoir again and then running a regular bleeding with the bleed valve on CSC and careful use of the clutch pedal as per the PMM article.

Thanks for keeping my thinking on the straight and narrow!

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Tom, you were right: overthinking. Squirted the old fluid out with one stroke of the clutch pedal, then refilled the reservoir and another press on the clutch pedal to flush it through. Refilled the reservoir awaiting gearbox reinstallation, and will bleed in the usual way.

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Got the gearbox in on the drive and have put in the transmission support bracket and mount so no jacks now.

So, I topped up the reservoir, plugged in the hard pipe into the hole next to the bleeder (all part of the CSC. Attached ed the Vizibleed bleeder on to the bleeder, opened it a quarter turn, pressed the clutch pedal which dropped to the floor, raised it up by hand and waited. Nothing...

So after a minute pressed clutch pedal again. Same result. Again waited a minute and repeated, same result ... And repeated a couple more times. Zilch feels in the clutch pedal which just drops to the floor. I have left it for now.

Checked the reservoir throughout and it's full and the above efforts have had no effect on the level.

My guess is there is a lot of air in the system, as because of the intermittent rain there have been delays with the hard pipe (clutch pressure pipe to CSC) not plugged in and probably taking in air...

What do members think?

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The pedal will drop to the floor with the bleed nipple open.  I'm not sure what you're waiting for?

Just keep pressing and pulling the pedal smoothly until fluid comes out of the bleed nipple.

Then keep pumping until there are no bubbles visible in the clear bleeder pipe.

Then close the bleed nipple and try the pedal.  It should work properly then.

(PS - Did you reconnect the reservoir to MC pipe?)

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Hi Tom, thanks yours. Will try again tomorrow as your advice. The reservoir to MC pipe has not been disconnected.

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12 hours ago, TDCI man said:

Hi Tom, thanks yours. Will try again tomorrow as your advice. The reservoir to MC pipe has not been disconnected.

No problem.  As that pipe wasn't disconnected, I would expect the fluid level in the res to have dropped with the first few pedal pumps even if it hadn't reached the CSC end.  I wonder if the bleed nipple is actually open.  A quarter turn may not be enough on this part.  You can open it more, the fluid won't just start gushing out.  Just take care not to open it so far that it feels loose as it can start taking air in around the threads at that point.

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Thanks Tom, so you understand the background ahead of reinstalling the gearbox, I previously pressed the clutch once to evacuate the old fluid (cloudy brown), filled the reservoir and pressed the pedal once more to flush as level down to minimum. Then topped up the reservoir to have fresh fluid ready for the new CSC.

Next couple of days were spent reinstalling gearbox (am working on drive with straps, boards, etc). This a day more than expected as a small critical oversight (tab stuck between box and engine at top which difficult to see) which had to be corrected (!).

The reservoir level had by then dropped again to minimum (fluid dribbling out of the hard pipe disconnected from the CSC (but always connected to the MC).

So topped up reservoir again (whilst doing so, bubbles seen from reservoir), and then back to my post yesterday.

With the half dozen pedal pumps I did (albeit about a minute between each to see if the hydraulic system would kick in). No change in the reservoir level after each pump (still full).

Noted your point about how much to open the nipple.

The reading I did on installing a new CSC (e.g. the PMM article links I sent earlier) recommend against repeated pressing of the pedal for a new CSC. This is why I am being careful (too much?).

Thinking of reverse bleeding by attaching a syringe primed with fluid to the bleeder to displace the air as where the hard pipe connects from the CSC to the MC the first couple of feet (from the CSC back) are horizontal and the next foot (after the hard pipe connects to the hose to the MC) is not much better as the first foot of hose is an S bend. Ample scope for air pockets...

For this method the bleeder would need to be open and allow inward fluid (under syringe pressure). But not sure if clutch pedal should remain up or down (thinking of the MC, not wanting to damage). Or whether the whole reverse bleed with syringe is a bad idea ...

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Ok, something strange is going on here.  If the bleed nipple is open & the res pipe is connected to the MC then air pockets in the MC-SC line shouldn't stop the fluid being pushed through by a pedal press.  You are right not to just keep pressing the pedal in this situation.

Leaving the pipe open isn't ideal but shouldn't have caused any damage in such a short time.  Best practice for future reference would be to plug the end of the pipe with some tissue and something watertight like a bit of disposable glove or something to that effect.

I wouldn't reverse bleed against the MC personally though that's your decision to make.  I think you'd be better off sucking the fluid through using a vacuum bleed instead.  (This is how it's generally done in garages, though they have access to compressed air tools which makes it easier.)

I would definitely double check the nipple is actually open before going any further though.

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Thank you Tom. The tip of the hard pipe was covered until a few days ago with a patch of plastic bag and elastic band. While it has been open it has had dribbling fluid though it (into a clean rag) and the reservoir has never dropped below minimum.

I may possibly be doing something wrong in 'when' I am opening the bleeder valve ... 

Anyway, will not reverse bleed now. To avoid undue pressing of the clutch pedal I will:

A. Buy a vacuum bleed kit (£12 eBay):

https://www.ebay.co.uk/itm/166882245933?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=T4QuoLCqQfa&sssrc=4429486&ssuid=yVFafxpISdO&var=&widget_ver=artemis&media=COPY

Can use it for brakes later. Unlike with a syringe I can monitor the pressure levels and it should be fairly easy to control. If you know of a better tool, please let me know.

B. Open bleeder and apply vacuum to nipple with hard pipe connected to CSC. Monitor reservoir level.

C) If B doesn't work then maybe close bleeder nipple, disconnect hard pipe from CSC and apply vacuum direct to the tip of the hard pipe ...

All the while the clutch pedal is up (not pressed).

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At the back of my mind, I half suspect that there's air in the MC itself.

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Well Tom, I bought the vacuum pump and passed loads of fluid through the clutch.

Initially, bubbles galore for the first half dozen passes. Now nothing but fluid for as many passes again

I tried a couple of gentle reverse bleeds to see if that would help shake things up in the system with fluid moving about the same speed through the hose (but other direction) as with the vacuum, but no difference that I can tell.

Clutch pedal doesn't drop to the floor now, but when pushed to floor (bleeder closed), stays there until lifted by hand. About half way up lifting, the pedal becomes springy (like a normal clutch) and has to be restrained by hand from moving too quickly (but is this a physical return spring or actual clutch pressure?).

I think the vacuum method has done what it can at this stage, but the clutch is still not satisfactory.

I read the Ford Focus (and many other Fords) clutch systems are quite horizontal (hence Ford's own manual for Focus shows reverse bleeding).

My plan is to buy a cheap pressure bleeder which runs off the spare tyre air but NOT use it as a pressure blender at first. Later, if all else fails, maybe I will but on low pressure like 10-12 psi.

So this is where I would like yours and members views ...

I plan to use the cap from the pressure bleeder that fits the reservoir, and plug in the vacuum bleeder to it, applying vacuum to the reservoir directly, rather than pressure, and draw any air bubbles up through the reservoir (as opposed to down through the bleeder). I think this is what is called 'dry bleeding'.

Has anyone tried this? Any thoughts?

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Hmm, I must admit, I can't remember anyone having so much trouble with a Mk2 clutch line before.

You're right about the pedal spring.  It's main job is to push the pedal up and off of the MC, otherwise the weight of the pedal would be putting constant pressure on it and accelerating wear in the system.

Brake fluid doesn't really flow like water.  So I'd generally recommend only bleeding in one direction otherwise you could be pushing air back & forth in the middle.

I am slightly concerned that the MC seal may be failing and letting fluid pass now.  But it's definitely worth trying a bit more bleeding before changing it.  I'm wondering if you can carefully disconnect the top pipe from the MC just enough for any air to be purged and then quickly reconnect it.  I watched a mechanic bleed a caliper by loosening the pipe slightly when the nipple was snapped, worked better than I was expecting.

Probably clutching at straws now but have you had the engine running?  The engine vibrations may help to shake any bubbles one way or the other.

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