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Floppy Clutch Pedal/Master Cylinder Fix

12K views 22 replies 6 participants last post by  Luciano710 
#1 ·
Recently the clutch pedal on my 2.5 V6 156 went floppy with only the last inch of travel actuating the clutch causing extreme difficulty in changing gear. On investigation found the fluid very low in reservoir, refilling did not restore clutch action.

Read forum and found a number of queries regarding this problem so I will outline my experience and correction of fault. The replacement job took about 4 hours but should be faster using the tips given.
Me and my Dad carried out the job together... He's far better at describing the job than me... so this is his write up!!! ;););)

Apologies for length of description but tried to describe the procedure in detail and problems experienced.

Diagnosis
Checked if slave cylinder situated just under the battery on the bell housing was operating, with the limited actuation of clutch pedal, and found there was some movement of the slave actuating rod with no sign of fluid leakage.
Next checked the clutch master cylinder actuated directly by the clutch pedal and found small drops of fluid coming from the rubber boot as clutch pedal was operated. So decided the master cylinder needed to be changed as the internal seals were obviously worn causing the leakage.
From the forum the change of the clutch master cylinder has given a number of people terrible problems mainly due to almost impossible access to the master cylinder outlet connection which is somewhere in the bulkhead.
On checking found no access to this connection also the rubber inlet connection was very close to the bulkhead and was going to be another headache to disconnect.Also one of the cylinder holding bolts was behind pedal work steelwork. Given what seemed an almost impossible task without decided to leave the old clutch master cylinder in place and replace the internal piston and seals with the piston from a new Master Cylinder as it was only the seals that was worn not the cylinder itself.

Job to replace cylinder internals
Remove the clip and washer from the pin securing the cylinder actuating rod to the pedal. Remove the actuating rod off pin, this was difficult as the rod moves at an angle to the pin as the other end of rod is in the cylinder but persevere it will come off . I used a large screwdriver as a lever and moving the pedal to aid the removal by changing the angle of pin to rod.Remove the rubber boot from the actuating rod which exposes the circlip which retains the piston in the cylinder. Using a circlip pliers remove the circlip, again not straight forward due to access. The old piston is now ready to withdraw from the cylinder, before withdrawing piston put some pvc on floor underneath cylinder and have a rag ready.
Before you remove new piston from new cylinder chamfer the leading edge of the actuating rod hole so it will help to get it on to clutch pedal pin.
Remove new piston from new cylinder as above (be careful not to damage the seals) and have ready to install in existing cylinder so as old piston is removed the new piston can be installed immediately, be ready with rag as fluid will come out as old piston is removed.
Picture of piston removed from cylinder ready to install in old cylinder is shown below.
(Picture actually shows the old piston with the new cylinder....I forgot to take a picture of the new master cylinder with all its bits removed!! Duh!! :rolleyes:)

Auto part Suspension part Tool accessory Transmission part Hardware accessory


Slowly push new piston into cylinder being very careful not to damage the seals as they enter the old cylinder. Replace the circlip, this is much easier than removal. Install the new rubber boot over rod on to existing cylinder.
Before installing the actuating rod on clutch pedal pin chamfer the leading of the bush on the clutch pedal pin to help ease the new rod on pin.
Install actuating rod on to clutch pin again a bit difficult but it will go on.I used a plumbers grips while at the same time moving the pedal up and down.
Be careful that the clutch pedal return spring (up inside the dashboard) does not come loose as it located by spring pressure and by moving pedal to remove and install actuating rod it can fall out of place. This spring must be in place before the actuating rod is installed on pedal.
Remove hosework above battery and remove battery to expose the bleed nipple on rear of clutch slave cylinder which is accessible through the battery tray cut-out.
Bleed clutch, I would advise bleeding until new fluid is visible.
After bleeding my clutch was functioning correctly.

Phew!!! Remember all the above is done while lying upside down in the footwell so it helps if you are flexible! Was a big relief when we completed this job successfully... been using the car all week and have had no problems... with reservoir level still at max.
Any questions then please message me and I will be glad to help if I can.This forum and its advice has helped me out on many occaisions. :):):)
 
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#3 ·
It's a little while since this was posted but wondered if all Master cylinders installed on 156 V6s are identical and from same manufacturer. How did you know the internals of one would fit exactly into the cylinder of another. did you find the exact same part or did you order from dealer and hope for the best
 
#4 ·
We took a bit of a punt. Ordered one from Shop4parts (I think).Then when we'd removed the old piston and measured it using digital calipers and compared it with the one we bought! It was exactly the same!
Glad to report all is still working well nearly a year down the line! :D
 
#7 ·
Recently the clutch pedal on my 2.5 V6 156 went floppy with only the last inch of travel actuating the clutch causing extreme difficulty in changing gear. On investigation found the fluid very low in reservoir, refilling did not restore clutch action.

Read forum and found a number of queries regarding this problem so I will outline my experience and correction of fault. The replacement job took about 4 hours but should be faster using the tips given.
Me and my Dad carried out the job together... He's far better at describing the job than me... so this is his write up!!! ;););)

Apologies for length of description but tried to describe the procedure in detail and problems experienced.

Diagnosis
Checked if slave cylinder situated just under the battery on the bell housing was operating, with the limited actuation of clutch pedal, and found there was some movement of the slave actuating rod with no sign of fluid leakage.
Next checked the clutch master cylinder actuated directly by the clutch pedal and found small drops of fluid coming from the rubber boot as clutch pedal was operated. So decided the master cylinder needed to be changed as the internal seals were obviously worn causing the leakage.
From the forum the change of the clutch master cylinder has given a number of people terrible problems mainly due to almost impossible access to the master cylinder outlet connection which is somewhere in the bulkhead.
On checking found no access to this connection also the rubber inlet connection was very close to the bulkhead and was going to be another headache to disconnect.Also one of the cylinder holding bolts was behind pedal work steelwork. Given what seemed an almost impossible task without decided to leave the old clutch master cylinder in place and replace the internal piston and seals with the piston from a new Master Cylinder as it was only the seals that was worn not the cylinder itself.

Job to replace cylinder internals
Remove the clip and washer from the pin securing the cylinder actuating rod to the pedal. Remove the actuating rod off pin, this was difficult as the rod moves at an angle to the pin as the other end of rod is in the cylinder but persevere it will come off . I used a large screwdriver as a lever and moving the pedal to aid the removal by changing the angle of pin to rod.Remove the rubber boot from the actuating rod which exposes the circlip which retains the piston in the cylinder. Using a circlip pliers remove the circlip, again not straight forward due to access. The old piston is now ready to withdraw from the cylinder, before withdrawing piston put some pvc on floor underneath cylinder and have a rag ready.
Before you remove new piston from new cylinder chamfer the leading edge of the actuating rod hole so it will help to get it on to clutch pedal pin.
Remove new piston from new cylinder as above (be careful not to damage the seals) and have ready to install in existing cylinder so as old piston is removed the new piston can be installed immediately, be ready with rag as fluid will come out as old piston is removed.
Picture of piston removed from cylinder ready to install in old cylinder is shown below.
(Picture actually shows the old piston with the new cylinder....I forgot to take a picture of the new master cylinder with all its bits removed!! Duh!! :rolleyes:)

View attachment 273025

Slowly push new piston into cylinder being very careful not to damage the seals as they enter the old cylinder. Replace the circlip, this is much easier than removal. Install the new rubber boot over rod on to existing cylinder.
Before installing the actuating rod on clutch pedal pin chamfer the leading of the bush on the clutch pedal pin to help ease the new rod on pin.
Install actuating rod on to clutch pin again a bit difficult but it will go on.I used a plumbers grips while at the same time moving the pedal up and down.
Be careful that the clutch pedal return spring (up inside the dashboard) does not come loose as it located by spring pressure and by moving pedal to remove and install actuating rod it can fall out of place. This spring must be in place before the actuating rod is installed on pedal.
Remove hosework above battery and remove battery to expose the bleed nipple on rear of clutch slave cylinder which is accessible through the battery tray cut-out.
Bleed clutch, I would advise bleeding until new fluid is visible.
After bleeding my clutch was functioning correctly.

Phew!!! Remember all the above is done while lying upside down in the footwell so it helps if you are flexible! Was a big relief when we completed this job successfully... been using the car all week and have had no problems... with reservoir level still at max.
Any questions then please message me and I will be glad to help if I can.This forum and its advice has helped me out on many occaisions. :):):)
Hi I hope you're still on the Forum!

Can I ask some advice on this please?
It should be universal for what I'm asking anyway...

On my 147 the Rod in the Clutch Master Cylinder has an integrated bush at the Pedal end.
(See photo) This had worn and split so I managed to get a replacement with superb intact rubber bush.

On removing the rod the internal piston and spring came out - with lots of fluid - which I really wasn't expecting.
(I was under the impression that the fluid and piston would stay put.)
If I'd had known i could've done a swift swap with the rods.
Anyway after clearing up I've left the old fluid to drain out into a jar as it's a bit murky.
I'm not sure if this possibly 19 year old fluid is just a bit tarnished from wear and tear, reaction to the spring metal, or possibly grease applied to the piston and seals on initial assembly...

Now I'm going to reinstall it all back together some advice needed please;

1. When re-installing the white plastic piston and rubber seals; should I use grease?
I have thick silicone grease NLGI 3 rated,
Silicone Spray oil,
Spray Lithium grease,
Copper grease,
Vaseline,
High Temp Grey Grease,
I'm guessing the Silicone grease as it's plastic parts and rubber seals will be best but it might be a bit thick so just a smear...
Does the brake fluid lubricate anyway? Would it mix ok with Silicone Grease?

2. The Rod meeting with the pin on the clutch pedal; Inside the Rod's rubber bush is what looks like brass, which will go onto a steel (I think) rod on the clutch pedal. I painted the rod with Kurust and smooth Hammerite paint (as the previous sleeve had rusted/ bonded to it causing the split bush)
Will thick Silicone Grease suffice here or should I use lithium?
I don't want that sticking again!

3. After this is all in place, I'll top up the brake fluid reservoir..
Will a few pumps of the Clutch Pedal will this sort out any air bubbles etc?..

Many thanks!!

942674


942675




942677


942678
 

Attachments

#8 ·
I'm still here! [emoji1303]
I am trying to think back to the job now... its a long time ago! [emoji1787]

1. I think I just smeared the two new seals on the rod with new brake fluid.

2. I used lithium grease on the bush connecting to clutch pedal rod. I guess any decent grease would be ok though.

3. To bleed the system theres a bleed nipple on the slave cylinder on top of the gearbox.
With someone pumping the clutch pedal you need to draw the air out from the slave cylinder end.

Hope this helps! [emoji1303]

Rob

Sent from my SM-G965F using Tapatalk
 
#9 ·
I'm still here! [emoji1303]
I am trying to think back to the job now... its a long time ago! [emoji1787]

1. I think I just smeared the two new seals on the rod with new brake fluid.

2. I used lithium grease on the bush connecting to clutch pedal rod. I guess any decent grease would be ok though.

3. To bleed the system theres a bleed nipple on the slave cylinder on top of the gearbox.
With someone pumping the clutch pedal you need to draw the air out from the slave cylinder end.

Hope this helps! [emoji1303]

Rob

Sent from my SM-G965F using Tapatalk
Ah fantastic and thanks for quick response!

1. Ah I see would anything else compromise the action?
I thought a smear of silicone grease might help protect the rubber and the brake fluid would find it's way on top of that I guess and possibly mix in.
Would it be any harm in doing that? Just a smidge?

2. Yeah I think most of the grease in the Clutch Pedal area I noticed was Lithium Grease. Just thought the silicone might be good for the rubber.

3. Ah thanks. Is that in the engine bay I guess? I'll have to do an image search I guess lol. Do I need a special tool to open the bleed nipple?

Many thanks!
 
#12 ·
It is accessible on the 156 without removing the battery .. but not sure if a 147 engine bay is different.

Don't be surprised when the clutch pedal stays on the floor .. there is no return spring to pull it back. It may take a few pumps to get the fluid moving.

And if that fulid is 19 years old .. it is way overdue for replacement! It will contain a lot of moisture now which corrodes the pipes from the INSIDE! When was the last time the brakes were done? Do them too!
 
#13 ·
Thanks I’ll take a look when there’s a break in the rain.
When I took the battery etc out I actually took a load of photos of the area underneath for future reference so that should help me find it...
Also from the video (and your pdf thanks -although it’s a 156 but still a T-Spark motor) - I know what to look for...

There is a return spring arrangement on the 147 clutch pedal; whether it’ll return completely from the floor if it’s been pumped fully down I’ll have to see but thanks for the tip...

Actually I have a recent-ish bottle of Tutela brake fluid that’s probably no more than 5 years old.
I’ll be using it to top up (so at least I can drive it) for now. If there’s not enough I can just dilute it with some water eh? 😉😆
I’m sorry just kidding!

I have a set of new pads and discs actually and plan to get callipers tastefully painted so it’ll probably be prudent to have a full brake fluid change also...
 
#15 ·
That's the awkward little "wotsit" .. mine never had the protective cover ..
 
#16 ·
Aha! I wondered what that was back along.....

I think with the air take nudged aside if possible it could be accessible, if not then I’ll take it off...
Not wanting to remove the battery plate again after all the faff not long ago!

Notice how around the area on my car it has a special anti-rust protective coating...
Oil! 🙄😆

On reading your pdf there’s something I don’t quite follow...
I thought bleeding pipe into the jar was just to catch the old fluid?
I’ve underlined it on a screenshot:

942877
 
#17 ·
It can suck back if you pull the clutch pedal back up without closing off the "valve" (pushing the hose back into the slave).. plus it shows how filthy the old fluid is!

If you simply push the pedal down and pull it back up it just moves the fluid up and down the pipework .. pulling back the air, dirt, etc. It's not a clutch system I'd ever come across before, but apparently now very common with plastic slave cylinders!

If you can, check the flexible hoses that feed from the reservoir too. There should be one joining two metal pipes above the gearbox .. to allow for movement .. when I had to have a gearbox change my mechanic spotted the one on my 156 was nearly worn through. It didn't appear to have even been clipped into the fitting to stop it moving. And as the gearbox hadn't been touched since it came out of the factory, that must have been like it from new!!
 
#18 ·
It can suck back if you pull the clutch pedal back up without closing off the "valve" (pushing the hose back into the slave).. plus it shows how filthy the old fluid is!

If you simply push the pedal down and pull it back up it just moves the fluid up and down the pipework .. pulling back the air, dirt, etc. It's not a clutch system I'd ever come across before, but apparently now very common with plastic slave cylinders!

If you can, check the flexible hoses that feed from the reservoir too. There should be one joining two metal pipes above the gearbox .. to allow for movement .. when I had to have a gearbox change my mechanic spotted the one on my 156 was nearly worn through. It didn't appear to have even been clipped into the fitting to stop it moving. And as the gearbox hadn't been touched since it came out of the factory, that must have been like it from new!!
Thanks for the tips.

as it’s been described to close off the valve after expelling old fluid & bubbles; then it won’t suck anything back up if I’ve closed the valve? Or is there enough fluid space in between the valve and the bleed nipple to make a difference on this?
I thought it was just flushing out old fluid and bubbles then closing the valve, pushing the clutch pedal back up drawing down new fluid from the reservoir I guess? Then start the process again...
I’ll see how much brake fluid I have spare seeing as I’ll probably have a brake fluid change along with the new discs and pads later on..

thanks for the tip about the pipes I’ll check that out...
How was the pipe worn through?
Simply chafing from not being tied down?
 
#20 ·
Are you closing off the slave feed hose after you push the pedal down? If not it will just suck the old bubble-filled fluid back from the outlet and jar. There is no shut off in the clutch system so it is a time-consuming process. And yes, I would expect t to be very dirty. It's not something that the garages change on a regular basis (they really ought too!) unless you ask (and pay for!)

  • Lift clip and pull out feed hose from slave slightly (it should stop as the clip catches it unless clip is completely pulled free)
  • Push pedal down slowly and hold it down (it should stay down as it has not return spring).
  • Close hose on slave (If you are doing it alone, you will need to push clip down to hold hose in place)
  • Pull pedal up
  • Repeat until all air bubbles have gone

Occasionally keep hose pushed and clipped into slave and test pressure on pedal. Not hard? Start again.

As your master cylinder is full of air if will take a while to suck fluid through from reservoir. The alternative is to try a pressure bleed tool (eg Gunson) which would force fluid into the master as it pressurises the reservoir slightly. Pulling out the feed hose will force the fluid to flow through the master and down to the slave.

Maybe even gravity? Leaving the hose pulled free from the slave and keeping the drain jar lower. I think I've read that some people have tried this method.
 
#21 ·
Are you closing off the slave feed hose after you push the pedal down? If not it will just suck the old bubble-filled fluid back from the outlet and jar. There is no shut off in the clutch system so it is a time-consuming process. And yes, I would expect t to be very dirty. It's not something that the garages change on a regular basis (they really ought too!) unless you ask (and pay for!)

  • Lift clip and pull out feed hose from slave slightly (it should stop as the clip catches it unless clip is completely pulled free)
  • Push pedal down slowly and hold it down (it should stay down as it has not return spring).
  • Close hose on slave (If you are doing it alone, you will need to push clip down to hold hose in place)
  • Pull pedal up
  • Repeat until all air bubbles have gone
Occasionally keep hose pushed and clipped into slave and test pressure on pedal. Not hard? Start again.

As your master cylinder is full of air if will take a while to suck fluid through from reservoir. The alternative is to try a pressure bleed tool (eg Gunson) which would force fluid into the master as it pressurises the reservoir slightly. Pulling out the feed hose will force the fluid to flow through the master and down to the slave.

Maybe even gravity? Leaving the hose pulled free from the slave and keeping the drain jar lower. I think I've read that some people have tried this method.
Thanks Gary.

I persevered including leaving the valve open overnight.
It collected a lot of old stuff and most bubbles gone.
I’ve left it overnight tonight too.

I found what really helped I found was pushing the pipe back in, clipping it secure, and then exercising the pedal pushing it in to get some pressure.

then releasing the pipe and then the collected bubbles rose up.
To expel the air only and not the rest of the new fluid I’d put in; I placed the jar as high as I could, to around the same height as the reservoir.
If the pipe was longer I’d have put it higher.
The old fluid had come out and I was getting fresh fluid coming through.

So all it took really was perseverance with getting the air out of the clutch master cylinder.

I think by morning all bubbles should have gone.

next is cambelt change (taking it to Indy garage to get it done)

then later will be brake discs and pads and will get brake fluid changed then too.
Then with what’s left I might just check the clutch valve again for bubbles and other old stuff to make room for brand new stuff.

earlier today with the clutch bleed pipe closed there was ample pressure in the pedal I reckon so should be good to go!
 
#22 ·
Great news ..

Disc and pads are relatively simple apart from the need to wind in the rear cylinders. I've used the proper tool and an assortment of odds and ends to do that!

I did a full bleed/refresh when I fitted braided hoses and the only thing to remember is don't let that reservoir run out as getting air in the ABS system is a nightmare sometimes to correct. At least with the brakes the pedal will return!
 
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