P38A Clutch slave madness...

The slave cylinder piston popped out on mine when the roll pins sheared so that is a lot of movement you have

Complete clutch kit with cover, plate and release bearing was installed along with a new dual mass flywheel and rear main seal all from Island4x4 and all seemed to fit perfectly.
It also had new roll pins for the clutch fork, and new bushes for the clutch fork shaft.
To be sure, I have just had a "to hell with it" moment, and now have the clutch flexi and master cylinder on order, as well as a new clutch slave push rod (but the 99mm one from a TD5 Disco) Should have them around tuesday or wednesday with a bit of luck.
Will plan on having one of the junior technicians here fit them one at a time, starting with the flexi, then the master and then the push rod, with testing between each stage to see what effects it and how, so I can report back here, but also to satisfy my own curiosity.
If nothing else, hopefully getting to the bottom of these odd symptoms and posting the results will help someone searching the archives here in the future, as everywhere I have found on forums regarding these symptoms seems to involve people asking "why" and asking for help, advice given, but then no follow up to say what worked, so hopefully my financial pain will help someone else in the future! lol

tomcat59alan said:

The slave cylinder piston popped out on mine when the roll pins sheared so that is a lot of movement you have

Click to expand...

Well that is the odd thing..
Measuring from a fixed point on the slave cylinder to the clutch lever cup, at rest, after being bled we measured 180mm
On the first depression of the clutch peddle and holding it down, the distance increased to 190mm
So the usual clutch fork travel seems to be 10mm
On each cycle of the clutch down, to clutch up again, the clutch slave returned, but by 3 to 5mm less on each cycle
Until eventually at 200mm after a few cycles, the slave cylinder started to leak, but had not quite extended the piston enough to cock and jam things up.

From this, it seems that after a bleed, with the system at rest, there is only 20mm of piston thrust before the slave will leak, about another couple of mm before it cocks in the bore and jams things up.

With the 10mm travel from clutch up to clutch down, that leaves just a 10mm margin before the clutch slave fails to seal, or 13mm before it looses its seal and cocks.

Having had the slave cylinder off the car and taken it apart, the piston can drive against its spring by close to 50mm without binding up the spring.

I would be happier with the slave having its rest point somewhere beyond the half way back position, so I hope with the 8mm longer push rod from the TD5 setup, that will provide 18mm of remaining clutch slave piston travel before it leaks or about 21mm before it cocks.. My feeling is, that as the piston has a diameter of about 20mm also, it having closer to its diameter as a supported bore depth when depressed, should result in a more stable piston, but 10mm that we have with the standard piston push rod, means that the piston has only a supported depth of half of its diameter, which although I am no expert on Range Rovers, seems a bit low.

Anyway, that is just my 2p worth from the observations so far, you never know, some unusual fault in the master cylinder could not only be causing the ratcheting out of the piston on each depression (pulling in additional fluid on each depression cycle), but also causing the slave to not be drawn back far enough against its internal spring... But having said that, the force of the clutch lever should be pushing it back as far as it needs to anyway.

I still feel at the moment that the clutch flexi being restrictive or collapsing internally on or during the return stroke, could be causing the master to pull in a small amount of additional fluid from the reservoir on each cycle.

If none of this works, the transmission is coming out, everything inspected, and if we can't see anything, it will get a new clutch lever shaft, clutch fork, roll pins and another clutch kit borrowed from a motor factor just to compare things.
If that does not work, I will get a crane to lift the p38 onto the roof of the workshop offices and it can sit there and have a jolly good think about its behaviour until it becomes a valuable vintage car!

I had an Alfa Romeo Spider some years back and the clutch flexi hose had collapsed or failed in some way internally and it gave me no end of grief.

They can't be terribly expensive (cough) and it would serve an elimination purpose because they can fail - although it's rare.

My gut feeling is clutch flexi.. But seeing as it has had a new clutch, flywheel and now slave, if I am changing the flexi, I may as well get a new master cylinder as well... So they have been ordered... But for the sake of scientific analysis, not to mention my curiosity and desire to post the solution here, the bits will be changed one at a time, starting with the flexi.
If the flexi cures it, I will still fit the new master, and then will re-evalutate the slave piston rest and extend positions, and probably fit the TD5 clutch push rod to satisfy my paranoia about it seeming to put the slave close to popping position when fully extended with the standard rod.

The genuine clutch flexi is about £75, so it isn't getting one of those, most retailers also list it as about £55 for an OEM one.. But Britishcarparts.co.uk list the same part number as £6.17, so I have ordered one from there, as well as the master cylinder.

I had bought a new standard clutch slave push rod from Rimmer Bros for £20 as I thought maybe the one I had was worn or incorrect, which turned out to be the same length as the one that was already on the car.. which for the price, seems to be the going rate everywhere, but the TD5 99.3mm part is about £2 to £4 everywhere for an identical part, but 8mm longer... Go figure!

Sh1t part hose should be ok as it doesn't have a bearing we wait with baited breath

Pump the slave out a bit ,then open bleed nip ,if the piston goes back on its own and fluid comes out under pressure ,there is a restriction in the pipe somewhere,has the pedal pushrod been tampered with,when the clutch was failing ..

Just a thought with these flexi hoses, if you go to your local hydraulic shop, they will normally make you a new one up there and then for a few quid. I've had power steering hoses and brake flexis from pirtek many times without problems.

When a new clutch is fitted the slave piston should be fully retracted. As the spinner plate wears slave piston will move along the cylinder to a new start position because the release arm does not go back as far. Automatically adjusting the clutch. If all has been assembled correctly, only thing i can see causing this problem is weak diaphragm fingers. Had this on an LUK pressure plate a few years ago were the diaphragm fingers had not been tempered and just bent.

It is a crazy situation for sure Wammers.

New master, flexi hose and new reservoir to master hose all fitted.

Bled the system, held the clutch slave back during bleeding... Clutch felt great on three depressions and popped out on the forth and leaked fluid everywhere.

In almost 30 years as a Porsche mechanic at the top of my game and a strong reputation, this Range Rover is the first problem that has ever threatened to beat me.

I have got to the point where I have a similar theory that the wrong clutch is installed or one with weak fingers.

When this clutch first went in, I managed to get half way through a test drive and the clutch felt great, but probably 20 depressions in total before it popped, but as time goes on, it seems to be less and less.

One of the guys here keeps saying he thinks the roll pins have sheered, but I keep telling him that if that has happened we would not be able to pop the piston back into the slave, bleed it and try again, the clutch arm would have moved around rather than always coming back to the same place with no play.

Just an idea, is there any way you can get a strong spring in there and let that retract the slave cylinder? If that works OK and goes all the way back then you know the issue is mechanical. If it doesn't work using a spring it has to be hydraulic.

Completely (I know) left field thought - crank thrust washers???
Well, it seems something is moving around.
When it shouldn't - or it could be a faulty clutch cover as suggested.

wammers said:

When a new clutch is fitted the slave piston should be fully retracted. As the spinner plate wears slave piston will move along the cylinder to a new start position because the release arm does not go back as far. Automatically adjusting the clutch. If all has been assembled correctly, only thing i can see causing this problem is weak diaphragm fingers. Had this on an LUK pressure plate a few years ago were the diaphragm fingers had not been tempered and just bent.

Click to expand...

ive had quite often now cover warps

Sarbirus said:

It is a crazy situation for sure Wammers.

New master, flexi hose and new reservoir to master hose all fitted.

Bled the system, held the clutch slave back during bleeding... Clutch felt great on three depressions and popped out on the forth and leaked fluid everywhere.

In almost 30 years as a Porsche mechanic at the top of my game and a strong reputation, this Range Rover is the first problem that has ever threatened to beat me.

I have got to the point where I have a similar theory that the wrong clutch is installed or one with weak fingers.

When this clutch first went in, I managed to get half way through a test drive and the clutch felt great, but probably 20 depressions in total before it popped, but as time goes on, it seems to be less and less.

One of the guys here keeps saying he thinks the roll pins have sheered, but I keep telling him that if that has happened we would not be able to pop the piston back into the slave, bleed it and try again, the clutch arm would have moved around rather than always coming back to the same place with no play.

Click to expand...

How about if the pins haven't completely let go? Unlikely but maybe possible?

I wouldn't go with LUK clutch, only flywheel. I'd go for the Valeo clutch kit as minimum spec. although I've just ordered an uprated one from https://www.clutch-fix.co.uk/.

After renewing everything in the hydraulics other than the pedal, pedal power spring, clutch fluid hard pipe, I parked it outside the front of the building so it could have a good hard long think about its behaviour.
But one of the technicians asking if I wanted the old clutch hydraulic parts throwing in the bin, has got me thinking about this again.

I have read the above comments and suggestions and think some of them are worth a go for sure.

As mentioned by WazzaJnr, one is fitting a return spring between the slave body and the clutch fork arm to pull the arm back fully each time we let the pedal raise to see if then it starts returning to the same point and not ratcheting out, then I will be faced with a choice... Run with that setup, knowing something somewhere mechanically isn't right, or then decide to remove the transmission again and look at what is going wrong inside the bell housing.

If it does not work, then the only real remaining thing would either be the linkage between the pedal and the master, or the clutch fluid hard pipes either side of the flexi, maybe one of them has a partial blockage.

I will also try all the other suggestions, such as bleeding it again, pumping it once to get it to ratchet out and then open the bleed nipple to see if it then returns.

I hope it does not end up being something in the bell housing, thats just a pain in the behind that I can do without.

Thanks for all the suggestions, even the one about the thrust bearings on the crank.. that does have me worried, as this did have a bit of a knock, but it really did sound like a camshaft knock or like a bad lifter and was something else for the to-do list.

The whole idea of hydraulic clutches is that they are self-adjusting to take up the natural wear over time - of course Ford thought they could do it better - anyone remember those ghastly ratchet arrangements on Escort and Sierra cable types - hideous.
Easy to put your mind at rest with crank thrusts - see if you can axial movement in the crank pulley - regret suggesting it now - it's not like the engine has any history of such behaviour, unlike some I could mention

The pedal is pushed back by the pressure plate fingers. So either that is weak / gone or the release bearing isn't releasing or something is wrong between the slave and master cylinder. There isn't much to go wrong! However, I had a similar issue yesterday. In the end I hooked up an Ezibleed kit and just pumped a litre of fluid through. Seemed to do the trick. You have to syphon the excess out the reservoir after and get it back to the max with engine running.

So since my last message on here we have been so busy in the Porsche workshop the Range Rover has sat out the front looking sad for itself, I have bought some other Porsche projects that will need my time going forward and all of this has given me time to reflect on the whole situation.

The reflection is that my ex girlfriend wanted this car in the first place back in 2010 and even though I told her it would be no good for what she wanted it for (Taking 4 dogs for walks in the countryside, two of which were elderly) the car was never needed, but it became part of the family.. The girlfriend was part exchanged for a better model in 2013 but the car remained with me and I actually enjoyed driving it from time to time, but it really did not have a purpose.

And that is the conclusion that I came to recently, the car does not have a purpose for me, it has a big question mark over it's head regarding the clutch issue, but otherwise is a good beast. But I also do not have time to invest in the Range Rover, so I decided to let it go. It is now on eBay starting at £0.01

http://www.ebay.co.uk/itm/272894176108

I really want the car to find a good home, with an enthusiast who wants to solve the clutch issue and will enjoy the car, or even if they want it to keep their pride and joy on the road with parts, I have to say that although that will be a shame, it will be better than the car just sitting there waiting for me to have time that I just do not have... I have Porsche projects that have been waiting 10 years for me to have time, so I need to be a realist.

I would like to thank everyone in here for all their help with this issue, I will direct the new owner once it is sold to this forum so they can join you, and this thread so they do not ask the same questions from scratch again.

So, so long and thanks for all the fish.

Understand why. Up to £310 now which isn't bad for a car with no MoT test certificate. Not worth buying it at that to do up and sell on. In 2 minds as to whether it is worth buying for parts!

What's this comment about? "the gearbox had an updated version of the gear lever pin fitted (as I learned this was the to-do thing to-do.. and having had it break once before, it seemed like a good idea) and the gearbox was re-fitted." The spiral clutch pins?