Manual clutch issue

[GREENPEDRO]

Hi All,

Pedro, the green 300TD manual wagon, has an issue.
Went to move out of the garage the other day and on putting my foot on the clutch, it went straight to the floor, No clutch !!!
Left it a few days and noticed a lot of hydraulic fluid on the garage floor.
Mopped the spill up and noticed that brake fluid reservoir was almost empty, topped it up again and noticed that fluid was leaking out between the manual gearbox and the clutch housing at about two drips per minute.

What does this mean, apart form the obvious of no clutch, is it a major issue or something more easily fixed.

All suggestions appreciated as I am a novice.

Cheers
Larry

[Thunderbolt]

Sounds like the slave cylinder, normaly pretty easy job dont know about these cars though
Cheers

[CraigB]

I don't know where the clutch slave cylinder is compared to where it is dripping, but it must be coming from there or a flexible line going to it. I don't know how readily available a replacement slave is or how much but that is the easiest solution. If it is in good shape you could get away with new rubbers or Power Brakes in Adelaide (and probably others) do a stainless sleeves on anything.

[mathuisella]

I have a manual as well, although i did the manual transmission swap myself in the back yard...

I would dare say your clutch slave is leaking internally and the liquid is coming out of the emergency fluid drain port between the slave cylinder and the gearbox.

Either that or my 2nd guess would be at the line that goes between the clutch slave and the liquid resovour, would need some good pictures to confirm where it's coming from.

clutch slave cylinders can be wholly bought online and through mercedes and i gather our sponsor here as well.

but the 3rd party ones won't be exactly the same, they may not have the same travel distance ect: so be careful

[GREENPEDRO]

Thanks guys for your interesting thoughts.
It makes sense to my limited knowledge that it may be the clutch slave cylinder gone ca-put.
It sits on top of the manual gear box and I can't see any fluid escaping from there so can only assume (dangerous) that the slave cylinder is leaking into the bell housing and dripping out via the emergency fluid drain port as suggested by Mathuisella (where did you dream up that name from).

Will do some more investigation before taking any action, so at present, Pedro is on stands in the garage.

Cheers
Larry

[mathuisella]

hehe, the name kinda suits it as if the drain port wasn't there, all the fluid would drain into the bellhousing and you'd end up with liquid all over the clutch plate(s) and that's just an accident waiting to happen....

a few good clear shots to trace the liquid where it's leaking from :) either the clutch itself, or the connection to the fluid res in the engine bay are my thoughts.

[GREENPEDRO]

Thanks Mathuisella,

I have very limited knowledge of this stuff, but can I presume that it is the slave cylinder on top of the gear box that is leaking into the bell housing and if so, doesn't that mean that fluid would have been leaking over the clutch and clutch plate assembly which, as you say, is not good.

Should I change the cylinder as a first option and see what pans out ?

By the way, there are no obvious signs of fluid leakage anywhere else apart from the slow drip from the join between the gear box and bell housing.

Cheers
Larry

[Bartman4800]

It is quite common.

Brake fluid is hygroscopic (attracts moisture) and should be replaced every 2 years.

The water drifts to the lowest point (in this case your slave cylinder) and starts to rust the cast iron body...
When you take it off, check the hose for cracks and replace if in doubt.


Bart

[GREENPEDRO]

Thanks Bart, good info and interesting about the moisture attracting properties of brake fluid.

I am in the process of trying to remove the slave cylinder and having a little trouble due to the very confined space to allow for hand and tool room etc.

Thanks again.
Larry

[CraigB]

I didn't realise the water went to the lowest point. That explains just how effective it is when people go to track days without changing fluid - disc and caliper get hot, boils all the water down there to gas and pedal goes straight to the floor. Happened to a friend in a 6.9 despite a warning - he looked very pale faced when he came in after running off the track! He was convinced something else had broken. I told him to leave it for a bit to cool and then try the pedal again and sure enough it firmed up again once the gas turned back into water. But when you need your brakes the most, when they get hot and that's when they will go.

[mathuisella]

ah yes, i remember now, oh the pain of such tight spare. My suggestion is to do what i did.

first spray some penetrative oil around it and let it soak for a bit.

then using every socket extension you have use this method... also may use the universal joiner/ knuckle joint, go at it from down the transmission tunnel further back. It makes life so much easier when trying to get to the starter motor, upper bellhousing bolts as well as the top clutch slave cylinder.

if you're in brisbane i'll be happy to pop over and help.

ow445.jpeg

[Bartman4800]

I know it is a bit of a hassle, but wouldn't it be easier to remove the propshaft and take the gearbox out?

That way you can have a good look at the clutch fork and the throwout bearing too...


Bart

[Bartman4800]

I didn't realise the water went to the lowest point. That explains just how effective it is when people go to track days without changing fluid - disc and caliper get hot, boils all the water down there to gas and pedal goes straight to the floor. Happened to a friend in a 6.9 despite a warning - he looked very pale faced when he came in after running off the track! He was convinced something else had broken. I told him to leave it for a bit to cool and then try the pedal again and sure enough it firmed up again once the gas turned back into water. But when you need your brakes the most, when they get hot and that's when they will go.

The brake fluid is lighter than water. Next time you replace the brake fluid chuck in a few drops of water in the jar with dirty fluid and see it pool on the bottom.
They lie on the floor of the jar in nice bubble shapes. Same applies for Diesel and any other fluid lighter than water...

[GREENPEDRO]

Thanks for the suggestions guys, I will certainly try them all and thanks Mathuisella for your offer of help.
Unfortunately, I am on the Central Coast of NSW, no where near Brisbane, but you are very welcome to come down the coast, a few beers await.

Cheers
Larry

[mathuisella]

Sorry to say it's a bit for for an afternoon trip...

How are you getting along with this any ways ?

[AMG]

Slave cyl is leaking past piston and cup seal.
When this occurs, it drips down the bellhousing and out through the drain at the front between the sump and gearbox, through a very small hole.
Wipe this area carefully and spray some brake cleaner onto the area, from a short distance, and try to direct it towards the hole, which will free up any blockage and also allow the remaining fluid to drain more readily. DO NOT pump it full of cleaner or use high pressure, or it will end up on the pressure plate and clutch disk.

When you have a brake fluid leak from this area it usually means the slave cyl bore is badly corroded, and the piston seal is toast.
It is common sense that BOTH the slave (and clutch master) should be replaced at this point with a refurbished or new pair.
Doing only one usually ends up in a repeat of this procedure very shortly after replacing only one... It is a well documented occurrence.

To bleed:
Bleed the front right brake calliper and make sure the fluid is CLEAN.
Attach piece of hose (aquarium air line works well for this) from bleed nipple on brake calliper to bleed nipple on slave cyl and crack open both bleed nipple screws. pump the brakes until the air bleeds from the clutch master up into the main master cyl reservoir. You will need to occasionally pump the clutch pedal to visually check the air in the line.

A Mityvac can also be used, but it's best used between the clutch master and clutch slave. Problem with this is brake fluid on interior footwell.
the master needs to be blocked to prevent fluid dripping, and the slave hose is used to pull the fluid through from the beake calliper bleed nipple.
It's not a 100% foolproof method, air can be introduced through the brake bleed and clutch bleed nipples, and you can end up with some air still trapped - but it's the best way without a power bleeder.

It's essential to make sure the brake fluid is clean, because any moisture and crud in the system will be shared between them.

Every time you replace your brake fluid (at least every 2 years) the clutch slave should be bled after the brakes have been bled.

This ensures long life on piston seals and cylinder bores, often eliminating costly premature calliper and master/slave overhauls.

I'm guessing you may have been looking for an 'easier' solution, but the reality is that there really isn't one. The clutch system on a 201 has less space to work in if that makes you feel any better- and the bolts are notorious for shearing threads in the alloy bellhousing when overtightened.

If you're pulling the gearbox, then I have a basic cheap common sense preventative solution for this issue.

:occasion5:

[tsharkey]

It's not a 100% foolproof method, air can be introduced through the brake bleed and clutch bleed nipples, and you can end up with some air still trapped - but it's the best way without a power bleeder.

Hi Joe - I have a power bleeder so .... is the hose between RHF Caliper to Slave Cylinder bleeders not required as pressure will push the brake fluid through to the slave cylinder, cycling the old stiff and any air out when the bleeder nipple is opened ?

I am about to do the fluid cycle on the manual wagon and have never bled the slave before.

Tim/

[AMG]

Tim, the bleeder hose form calliper to slave cyl isn't required if you have a power bleeder - you can bleed the clutch in the same way as you bleed the brakes.

Note this is for master cyl reservoir pressure bleeders. If you're using a mityvac, then you'll have to create a GOOD seal on the slave cyl, and you'll still have to prime the clutch master - I used a long line to return fluid to the master reservoir, after I used the fluid evacuation pump to pull the line clean. That way you can be sure you have good clutch pedal, and you can also reverse bleed the slave cyl and line to where it joins the clutch master. A bit fiddly, but I have a braided line to the clutch master hardline and a bleed nipple extension line running to the tunnel, so it is easier for me to bleed the circuit.

I had issues with a non-functioning clutch master air bleed in the feed line from the master reservoir, so After persisting with all the possible 'bleeding methods' I opted for a section-by-section approach.
This way I can power bleed the clutch master and slave in both directions if need be, without getting under the vehicle.

If you have the means to install a slave bleed nipple extension line, it will save you a lot of frustration. The good news is that it's deadnuts easy to get a good braided one fabbed up, and it will make life easy.

I'm not a fan of the rubber slave line location in the 16v, it sits right above the exhaust downpipes, and is less than ideal, so the braided line served an additional protective function for serviceable life.

The clutch slave bleed thread is 6mmx1mm pitch, so you may need to fabricate a banjo bolt fitting or drill and retap the hole to take an 8mm fitting or 1/8 BSPT fitting depending on what you have access to - best thing is to get your mechanic / brake specialist to do this for you while the cyls being refurbed (or on a new slave) if you don't have the required tools.

[tsharkey]

If you have the means to install a slave bleed nipple extension line, it will save you a lot of frustration. The good news is that it's deadnuts easy to get a good braided one fabbed up, and it will make life easy.

Joe - What a great idea, thanks for the suggestion (I would not have thought of it !)

[Tony From West Oz]

Joe - What a great idea, thanks for the suggestion (I would not have thought of it !)

I have sent you a PM. So has Methusilla
Please contact him.

[GREENPEDRO]

Thanks AMG for those detailed instructions and advice.

I am still waiting on the new slave cylinder to arrive from MB Spares so not up to the bleeding process yet but will certainly refer back to the instructions.

Thank you
Larry

[GREENPEDRO]

Well, installed the new clutch slave cylinder with some difficulty but of course, still no clutch.
Used MightyVac to attempt to bleed clutch but still no clutch as it appears that air keeps leaking into the system.
Reading all the advice from the helpful forum members, I have now switched attention to the clutch master cylinder that I believe resides near the clutch pedal in the drivers footwell.
I hope this is the way to go.
Cheers all and thanks for the help.

[CraigB]

My gut feeling, it is just air and I wouldn't be touching the master. If there is no fluid leakage when you look up at the master and it was working and then it stopped and you found a puddle of fluid under the car and perhaps wet around the slave you replaced.... then even if you take it to a specialist to have them bleed it, it might save you time and expense.

Did you try repeatedly pumping the clutch pedal, say 10 times quickly and then try to put into gear? if it works like that then definitely air.

And you can drive a car without a clutch. If cold you might want to start the engine and get it warm so it easily restarts first. Then put it in 1st gear and turn the key while it is in gear and it should start and take off. Once mobile if you match your revs you can change gears - say rev it in first, back off accelerator and it should slip out of gear when you pull the lever and just put gentle pressure on the lever putting it into gear and as the revs drop to the right range it should just slide into gear without crunching.... etc. for other gears. Being a diesel if it will start on starter in second, less gear changes. And if you get to say traffic light and need to stop, slide it into neutral as you approach, stop, turn off engine, into gear and start again. You wouldn't want to drive in peak hour but it will get you home or maybe a short distance to mechanic. I once drove a car from Sydney to Adelaide like that though when a clutch rod on a manual clutch broke!

Anyway, just my thoughts - see what others think

[GREENPEDRO]

Thanks Craig for that advice and I have some good news.
As you said it is probably just air so I kept trying to bleed the system using the mighty vac, I was surprised at how much air was coming through. I did look at the master cylinder under the dash but chose to leave it alone as there was no evidence of leaks etc.
I also tested the mighty vac and added plumbers tape to some of the threaded components as I was suspicious it was not air tight in itself.
After numerous bleeding sessions and pumping the clutch pedal it finally started to return the pedal from the floor and the air bubbles reduced dramatically.
As the vehicle was on stands, I started it and engaged 1st gear, it then would not come out of gear so turned car off.
After fiddling and diddling with the gears and clutch, finally everything seemed to work.
Took car for a short test drive and (fingers crossed) all seems to be working even better than before.

So thanks for your help, so glad not to have gone further with it.
Cheers
Larry

[AMG]

The clutch master has an internal air bleed built in - when the pedal retracts from the floor, it returns the cylinder excess fluid back up the wet line (along with any air) to the master cyl reservoir.

Over time this has been known to fail on really cruddy old clutch masters, a byproduct of never being bled, dirty brake fluid etc etc.

when you put a new clutch master / slave in, inevitably there will be an air lock in the clutch master as well as a little bit of residual air in the slave, which is one of the reasons the reverse bleed procedure is recommended in many applications.

One thing I found was that if the cylinder was bled and then left overnight, then slowly depressing on the clutch pedal first in the morning will reveal if there is air trapped by the spongy pedal feel, this will then migrate back up the wet line to the reservoir when the clutch pedal is released. It's important to not fully depress the pedal, and to allow a bit of time for the air to migrate back up the wet line to the master reservoir. After about 15 minutes and a few pumps on the pedal, you will feel a much more solid pedal if there was any air in the master.

On the 16v it was a little more difficult simply due to not having any space to effectively work that 7mm bleed nipple on the slave cyl and the inability to access the clutch master effectively in the footwell when I first undertook the job.

Second time around however, and everything became painfully obvious. Then with a new clutch disc and flywheel, everything felt like it 'wasn't quite right' with takeup point etc. I knew there was aire in the line and it frustrated me no end. I left it overnight and performed the aforementioned procedure... I could feel the change in pedal and knew I had an airlock, and just hoped it was going to migrate back up the line, like I was told it would.

Within a few days everything had bedded in properly and the clutch was beautiful. It did take me a few 'takeoffs' to get the bite point just right initially because the clutch felt like it wasn't properly disengaging, it was just the air in the line - but as the disc bedded in, the pedal feel just got better and better.

It sounds like you are in a similar situation and things will work out if you give it a little bit of time and a few clutch pedal pumps.. Let us know.

[GREENPEDRO]

Thanks so much AMG, your detailed descriptions are very enlightening.
I do not have the knowledge of what you talk about to put it into action but I do get the gist of what you are saying.

I am just grateful that, at present, my clutch and gears seem to be working OK although I would not have been surprised if I had an issue with the master cyl, I will attack that if it presents a problem down the track.

Thank you so much to all that have contributed to this issue, Pedro is grinning, as it is back on the road as my surfing woody.

Cheers
Larry

[John Green]

Factory approved method of bleeding clutch after either master or slave cylinder replacement is as follows:

- run a clear tube (from bunnings) from the r/h/f brake caliper bleed nipple to the slave cylinder bleed nipple
- pressurize brake system by pushing on pedal
- open both bleed nipples, do not allow brake pedal to go to more than 70% of travel to floor
- close off caliper nipple when brake pedal at 70% and re pressurize system
- repeat multiple times

Essentially you need to push the fluid though the system backwards.

[mathuisella]

Hey, I've tried the factory approved method before on a couple of my w123's, but nothing seems to work better than the 2 man job of opening and closing the bleed valve on the clutch slave while a friend pumps the clutch pedal.


put a clear line from the clutch slave release valve/nipple into a glass jar.

Press clutch a few times, builds pressure and holds the clutch pedal down, open up clutch bleed valve and watch the air bubbles come out. after a second or two, liquid without bubbles will come and that's when you tighten back up the bleed valve screw. Rise and repeat until little by little there's no more bubbles coming from the clutch slave cylinder and the clutch feels good :) , you may need to top up the clutch liquid resovoir in the engine bay half way through this method, but it's never failed for me.

[GREENPEDRO]

Thanks John Green and Mathuisella for your thoughts.
I did read about the RH brake/slave cyl combination bleed but, due to my limited knowledge, decided to try the mighty vac suction bleed from the slave cyl end. I was a little concerned about letting air back into the brake system as I had a lot of trouble with the brake bleeds and did not want to upset them.

As it has now turned out, I may have an air lock somewhere in the clutch system because;
Took Pedro for a few short (1k) runs around home after the final bleed and all seemed OK.
Next day ventured further and after a few Ks, could not change gears and gears appeared to be stuck, also clutch was not returning from the floor correctly.
Luckily, I was in a side street, as it was morning peak at the time, so was able to pull over without inconveniencing anyone.
Pumped the clutch for a while and eventually the gears were able to move.
Continued to the beach, about another three Ks, had a surf and drove home with no issues at all. (A mate followed me home as a back up)
Have since tested it a few times around home and all seems fine although I have lost confidence in the car at present.

Correct me I am wrong but I plan to do another bleed with someone pumping the clutch etc, as the bleeds I did were with me under the car and periodically getting up to work the clutch, then back to the mighty vac bleed - not ideal I know but had little choice at the time and was impatient to get Pedro back on the road.

Sorry to be a bore with all this but perhaps other forum members may gain some knowledge.
Cheers
Larry

[mathuisella]

http://www.jimrothe.com/volvo/clutch_bleeding.html

The two-man method
This is probably the oldest method out there: get somebody to step on the pedal while you open the hydraulic line, and have them release the pedal after you close the line. Then repeat that cycle, ad infinitum, until the line is completely flushed with new fluid. Be careful about leaving the line open when your partner releases the pedal, or you'll just be sucking air into your lines, which is exactly the opposite of what you're trying to do.

There are some advantages to this tried and true method. It's cheap, it's reasonably fast, it's fairly reliable, but there are some occasional difficulties in rounding up a helper when you need one, and you're bound to get annoyed with each other. What's more, he'll drink half of your beer or, if you were foolish enough to recruit your wife or girlfriend for this effort, you'll have to buy an expensive dinner. Maybe this isn't so cheap after all.



person 1 ( person inside the car)
person 2 ( person under the car )


Person 1 = pump clutch pedal until good pressure is felt and holds pressure on the clutch pedal with their foot Calls out "Holding down"

person 2 calls out "okay, opening"

once air bubbles are releases and liquid is coming through should only take 1/2 a second ( person 1 should be holding pressure on the clutch pedal and pushing it to the floor as liquid is released from the slave bleed nipple valve)

Person 2 closes bleed valve on clutch slave

person 2 calls out " okay closed, pump again "


repeat this until person 1 feels good pressure on the clutch without needing to pump it a couple of times first. Person 2 will also know when it's time as less and less old liquid/air bubbles will come through the release bleed nipple/valve each time you go through these steps.

Hopefully this makes sense.

I tried all the 1 man methods and just came back with a friend to do it this way and it's worked every time. old method, tried and true.

[Christo C]

I’m still rocking with laughter at John Green’s method - never knew the made clear tubing long enough to run from Bunnings to my place!

[GREENPEDRO]

That's funny Christo, good pick up but I think we all knew the reference to Bunnings.
Thanks Mathuisella, will get a mate to help as described. I kind of knew that was best to do but was trying to short cut it, I have learned more.

[CraigB]

just a quick response to Larry's points.

Mityvac - great for finding leaks etc in the vac system but i have never successfully used it for brake bleeding. I think the instructions say to use 'silicone grease' on the bleed nipples to stop air slipping by it - I've asked a couple of places for silicon grease and just got blank faces. I'm interested if anyone has a successful method to seal those threads. You are winding it in and out and air can slip by the smallest gap - i doubt thread tape would do it.

I like the idea of things under pressure rather than risk of sucking air, so I reckon JG method sounds good but the other direct method no reason why it won't work.

Your description though I still reckon still just got a bit of air in there and if I used my mityvac that's exactly what i would expect!

[GREENPEDRO]

Thanks CraigB, interesting analysis on the mityvac, I don't think, having used it, it is the most ideal as a bleeder, however it did work to some degree.