Leclance Posted March 26, 2018 Share Posted March 26, 2018 Hi all, i need a little advice on an odd problem I’m having after replace my clutch master and slave cylinders. I have spent a while trying find anything similair on the forum but with no joy. After replacing both ends (master and slave) and taking lots of advice from forum bleeding I have successful(ish) bled the clutch . After tightening everything thing up and giving the peddle a couple of pumps the pedal goes completely soft and I can’t disengage the clutch. When this happens I have double checked the clutch fluids reservoir and it’s sits at the same level . I have tried this with both ezebleed and the conventional way . There is no evidence of any clutch fluid leaking anywhere . What have i missed? thanks advance lec Quote Link to comment Share on other sites More sharing options...
miketomcat Posted March 26, 2018 Share Posted March 26, 2018 Why did you change in the first place. Sounds to me like you have a release arm/bearing issue. I've had arms punch through and snap at one end. I've also seen release bearings melt. All of the above would give the issue you speak of. Mike Quote Link to comment Share on other sites More sharing options...
bushwhacker Posted March 26, 2018 Share Posted March 26, 2018 Hi, Make sure the slave cylinder is in the correct way up with regards to the fluid in pipe and the bleed nipple. Bleed nipple to the top, pipe fitting to the bottom. Quote Link to comment Share on other sites More sharing options...
Leclance Posted March 26, 2018 Author Share Posted March 26, 2018 25 minutes ago, miketomcat said: Why did you change in the first place. Sounds to me like you have a release arm/bearing issue. I've had arms punch through and snap at one end. I've also seen release bearings melt. All of the above would give the issue you speak of. Mike Thanks for you reply mike I changed them because the clutch pedal got gradual softer over a couple of days then finally gave up (this was during the last cold spell we had. The slave had lots of oil around it . I assumed it was just age on the cylinders and they are cheap enough. What you have suggested may we’ll be my problem . Is there an easy way to identify this ? Obviously other than your clutch pedal goes soft . Quote Link to comment Share on other sites More sharing options...
Leclance Posted March 26, 2018 Author Share Posted March 26, 2018 (edited) 13 minutes ago, bushwhacker said: Hi, Make sure the slave cylinder is in the correct way up with regards to the fluid in pipe and the bleed nipple. Bleed nipple to the top, pipe fitting to the bottom. Yes I got it wrong the first time but have corrected . Same problem ! Cheers Edited March 26, 2018 by Leclance Quote Link to comment Share on other sites More sharing options...
simonb Posted March 26, 2018 Share Posted March 26, 2018 (edited) Have you set the master cylinder free play at the pedal box? Edited March 26, 2018 by simonb Quote Link to comment Share on other sites More sharing options...
miketomcat Posted March 26, 2018 Share Posted March 26, 2018 2 hours ago, Leclance said: What you have suggested may we’ll be my problem . Is there an easy way to identify this ? Obviously other than your clutch pedal goes soft . If you pull the slave out you might be able to see/feel. An endoscope would be great. But otherwise it's eliminate everything else first because the gearbox and engine need to be split. Mike Quote Link to comment Share on other sites More sharing options...
Leclance Posted March 26, 2018 Author Share Posted March 26, 2018 Mike im rebuilding a 3.9 at the minute so if I have to split engine and gearbox I might as well finish the build and take the lot out . I’m replacing the box for a zf auto so the lots coming out . It’s gonna take a while to get finished (weekends ) and wanted to keep it going until it’s ready. what I can work is why the pedal firms up and then after a couple of presses goes completely soft again . (No viagra jokes ) Quote Link to comment Share on other sites More sharing options...
Leclance Posted March 26, 2018 Author Share Posted March 26, 2018 1 hour ago, simonb said: Have you set the master cylinder free play at the pedal box? No not accurately , the travel on the pedal isn’t the problem as when I first bleed it it’s fine. Quote Link to comment Share on other sites More sharing options...
miketomcat Posted March 26, 2018 Share Posted March 26, 2018 You could try reverse bleeding it ie drain it down and pump fluid in from the slave. Mike Quote Link to comment Share on other sites More sharing options...
Leclance Posted March 26, 2018 Author Share Posted March 26, 2018 I’ll probably give that a go , gonna need shares in dot4 at this rate ! Quote Link to comment Share on other sites More sharing options...
Ex Member Posted March 26, 2018 Share Posted March 26, 2018 Pull the slave off of the bellhousing. Let it hang don from the flex line. Open the bleed nipple and it will bleed by gravity. They can be difficult to bleed in place unless you have the knack. Quote Link to comment Share on other sites More sharing options...
simonb Posted March 26, 2018 Share Posted March 26, 2018 1 hour ago, Leclance said: No not accurately , the travel on the pedal isn’t the problem as when I first bleed it it’s fine. If the pedal height is not set correctly, the master won't recuperate properly - in other words let the fluid in and out of the slave - as the piston in the master won't be in the right place - and you will have no/or very little clutch action. A change of master will always need the pedal travel to be reset. Not trying to be rude but as a newbie, I would suggest trying the advice given by others - red90 has also given your a fail proof tip - before dismissing the advice out of hand. Quote Link to comment Share on other sites More sharing options...
western Posted March 26, 2018 Share Posted March 26, 2018 I'll 2nd the always re-adjust the clutch master cylinder pushrod after fitting, then it should bleed fairly easily. Quote Link to comment Share on other sites More sharing options...
Leclance Posted March 26, 2018 Author Share Posted March 26, 2018 5 minutes ago, simonb said: If the pedal height is not set correctly, the master won't recuperate properly - in other words let the fluid in and out of the slave - as the piston in the master won't be in the right place - and you will have no/or very little clutch action. A change of master will always need the pedal travel to be reset. Not trying to be rude but as a newbie, I would suggest trying the advice given by others - red90 has also given your a fail proof tip - before dismissing the advice out of hand. Ok fair point didn’t mean it to sound dismissive , or rude but on re-reading I can see how it could come across . Wasn’t my intention to dismiss out of hand I’m just trying to make sense of the aDvice I’m being given . No offence meant . The thing I’m struggling with is why it would loose pressure after it had been bled. As for red90,s advice that makes oerfect sense just hadn’t checked the forum to reply. Always happy to be wrong , im off to research how the dam master cylinder works lec Quote Link to comment Share on other sites More sharing options...
simonb Posted March 26, 2018 Share Posted March 26, 2018 (edited) On first pump, master piston moves and closes off the fluid input and fluid transfers to output port and then to slave. There needs to be sufficient free play at the master to allow its piston to move back, so that the input port is exposed again for more fluid to enter. Similarly when you release the pedal, the master piston must move enough to allow fluid back out of the slave to the reservoir. Sounds like you are getting fluid initially on the first stroke and then master piston doesn't have enough movement, which then blocks a port. Keep it simple. Bleed as red90 mentioned. A variation on this is to use 2 long bolts to secure a metal bar or stout piece of wood across the slave cylinder with the push rod removed. You can then pump the pedal with no danger of the slave cylinder being expelled. 2 pumps and it should be bled. Then refit the slave, reset the pedal travel and go from there. With the slave dangling, even if the master is not set up it should bleed ok. Pedal travel/freeplay needs to be set with everything in a "normal" position/state. Can't remember if the V8s have a cast clutch release arm or if they are pressed steel like the Tdis. If its cast, no chance of the arm failing, if it pressed steel, they usually fail instantly rather than go soft. Also if its a pressed steel arm its worth tie wrapping the push rod clip to the arm - if you have the gearbox off. But it will work all ok without the clip. Edited March 26, 2018 by simonb Quote Link to comment Share on other sites More sharing options...
Leclance Posted April 2, 2018 Author Share Posted April 2, 2018 Got my first couple of hours free on Friday to do this, spanners don't fit inside the master casing ! Flare nut spanners arrived yesterday , just need to get rid of the in laws then I can give it another try (worst case I have a grinder) Q jokes about the in-laws. The back is loaded with stuff thats going to the skip and its really starting to stink now. Quote Link to comment Share on other sites More sharing options...
simonb Posted April 3, 2018 Share Posted April 3, 2018 (edited) Slacken off both nuts on push rod either side of pedal arm. Use the stop bolt in the pedal housing to set the pedal height. There should be no load on the rod at this point. Use a pair of pliers to grip rod and make sure its fully out. You can then adjust nut nearest to bulkhead using you fingers to get the free-play needed. Then wedge pedal down, either in cab or with a screwdriver inserted between the pedal arm and pedal box. You can then use a spanner to tighten the "radiator" end nut. Wedging the pedal down whilst you do this ensures the inner nut (and rod) stay put. Edited April 3, 2018 by simonb Quote Link to comment Share on other sites More sharing options...
Leclance Posted April 9, 2018 Author Share Posted April 9, 2018 Tried everything above - still no joy. I went basic basics setup the cylinder in the vice, added a pipe section and tried to pump through some fluid. - no fluid. Forced through fluid with the easy bleed then hammer closed the end of the pipe . moved cylinder back and forward and got no compression for ten or so strokes . On the tenth ish the cylinder compressed and locked, I release and pushed forward a couple or times then the pressure released completely , back to no compression again. I setup the old master cylinder in exactly the same way (the master was ok when I took it off, its was cheaper to buy the pair so I might as well replace the pair). Bled the pipe again , closed of the end then immediately got pressure when trying to compress the pedal . tried a few times and the pressure stayed . I put the old cylinder back in the truck and re bled the system. The pedal works Fine now, I can only assume the new master cylinder was faulty from , maybe just the cylinder seal isn't siting properly. Oh well , thanks for you advice on this one but maybe I should have stuck to , if it aint broke the don't fix it. Quote Link to comment Share on other sites More sharing options...
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