Somebody please help me! Here's the scoop: I have a 300td with a 4-speed manual, (factory original) and the clutch won't engage. It started loosing clutch/brake a couple of weeks ago, and like the fool i am, i procrastinated and just kept topping it off. Towards the end i was noticing some shuddering as i put it into 1st and 2nd gear for the first 5 or 10 minutes of driving, then it would seem to get better. Finally last week i lost clutch altogether. I bought new master and slave cylinders thinking it had to be one of them and put them in yesterday. MS went in easy enough, SC bolt pattern turned out to not fit, i ended up pulling out the piston from the new one and installing it in the old SC (seemed to fit fine, moved freely, fluid did not leak out by the piston when i plugged the hole and pushed the piston). I put my "rebuilt" SC back in full of fluid, tried just about every technique for bleeding the line that i read about, and still the clutch wouldn't engage.
Additional information: The old MS definitely had been leaking, (down onto the floor below the pedals) but when i pushed on the piston with a screwdriver it seemed to hold the pressure without leaking.
One more thing: When i removed the old SC there was no evidence of the slotted spacer/gasket that my Haynes manual mentions-the SC was bolted directly to the trans. Also, the old SC prior to my "rebuild" DID leak some fluid around the piston when i plugged the inlet and pushed on the piston.
When all was done and still not working i loosened the nut at the bottom of the MS to make sure it wasn't totally dry in there, and fluid almost squirted out, suggesting that it was at least partially bled. Also, fluid had reached the top of the hose at the reservoir.
Does this seem symptomatic of fluid having gotten into and soaked the clutch? Any guesses? I'd really appreciate some insights. I love this car and want to keep it on the road forever!

Thanks in advance.

Aaron

It seems unlikely to me to have gotten on the clutch disc. I suspect bleeding problems. It is really really tough to bleed these clutch hydraulics. I suggest searching here for information.

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

X2, I suspect bleeding problems also......here is a post that I saved from a member here. I have done allot of clutch bleeding, using the brake slave to clutch slave method but last time I used the oil can method which worked well but the method described in this post seems like it might be the way to go.

I'm hopping Beagle doesn't mind that I pass along his post.

"1) Remove clutch feed pipe from brake M/C and drain reservoir. Replace feed pipe and refill to max with new fluid.

2) Remove pipe from slave cyl. and cap the pipe end with one of the bleed nipple rubber cups.

3) Undo bolts and remove slave.

To re-insall:

1)Thoroughly bench-bleed the slave leaving the push rod fully extended. Ensure all bubbles are out and fluid is filled level with the top of the pipe connection.

2) Remove the rubber cup and let at least an eggcup full of fluid drain down to replace old fluid in clutch M/C and then tighten pipe connection. Don’t pump the pedal!.

3)As the piston is pushed back in as you bolt the slave back on any air still in the pipe is pushed back up and through the M/C. Let it stand at least 15 mins before pumping pedal slowly.

4) Top up the reservoir and you’re done!

If fitting new slave and M/C:
1a) After fitting new clutch M/C, re-set pedal free play. Before connecting pipe to slave, fill res. and when fluid is running right through, cap pipe end as before. Let it stand for 10 to 15 min and gravity does the job. DON’T pump the pedal! Reconnect slave as in (2) and (3).]

The system is self-bleeding anyway but the trick is to get all the air out of the slave piston before re-installing it.

[B]Just BTW...... this method and procedure works equally well on the brake hydraulic circuit./B]
This method and procedure works equally well on the brake hydraulic circuit.
I.E.. - You can R & R the brake M/C or a caliper without having to open any bleed valves or re-bleed the whole system.

Example:-
R&R Brake M/C:
After replacing and reconnecting the bench bled M/C push a caliper piston in a few mm on both front and one rear wheel to push the air bubble trapped in the loop of the pipe into the M/C and then you’re done!

R&R a Caliper:
Cap pipe end with a bleed nipple rubber cup when removing caliper/s. Keep Res. topped up! Bench bleed with flex hose attached and with the piston on the bleeder side left at least 6mm out - but I guess you'd figure that!.
Pressure bleed by pushing the caliper piston back in once reinstalled and you’re done.

It is useful to have a few screw plugs for pipe fittings to keep fluid in and dirt and air out when refitting bench bled parts. A small can with a 2ft length of old brake pipe soldered in the bottom works well for gravity bench bleeding if you are doing a lot of this sort of work.

Corrosion is the result of water condensation in the air space in the reservoir being absorbed by brake fluid and settling in the lowest areas of the system. By keeping the reservoir topped up well above the max. level, air space (and thereby condensation) is reduced to an absolute minimum inhibiting corrosion".

Have a nice day.

Beagle
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1985 Euro 240D 5 spd 140K
1979 240D 5 spd, 40K on engine rebuild
1994 Dodge/Cummins, 5 spd, 121K
1964 Allice Chalmers D15 tractor
2014 Kubota L3800 tractor
1964 VW bug

"Lifes too short to drive a boring car"

Thanks for all the info, I'll try this today. So, do you think the absence of the spacer on the SC is inconsequential? Is the only purpose of it to allow access in to check the clutch adjustment? It would seem like the piston on the SC is traveling in farther because it's missing on mine. Maybe this doesn't matter.

Aaron

I'm hoping Beagle doesn't mind that I pass along his post. No problem

I’m afraid that was a bad idea to put a new piston into an old cylinder. You should have taken it back and exchanged it for the correct one. I believe there are 2 bore sizes. Corrosion in the cyl. is usually why they fail and could well be your new problem now.

When I bought my slave several years ago I remember that they told me there were two bore sizes with different bolt-hole positions – I think ?? 19Ø and 20Ø, don’t know which is which. I identified mine by bolt position. Maybe Stevo or someone else here can clarify? I think he changed his recently?.

There should have been no pressure in there. Check that you have free play on the pedal – about ¼ inch - adjustable with eccentric bush. The M/C piston must be fully out to clear the self-bleeding port.

The spacer is 2mm thick and leaving it out will not affect operation of clutch. Its purpose is to check wear with a gauge.

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Beagle

X2 on the thick slave gasket, no gasket needed, at least I have put it together that way with no problems.

As Beagle suggested it would be a good idea to swap in the proper slave. Your TD must have had the two piece iron tranny and your new 5 speed box is the one piece aluminum box which is why the difference in slaves. (the throw out bearing is also different) Installing slaves on the 300s is such a pain compared to the same job on a 240. I dropped the tranny mount, lowering things to give a little better access for my fat hands.

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1985 Euro 240D 5 spd 140K
1979 240D 5 spd, 40K on engine rebuild
1994 Dodge/Cummins, 5 spd, 121K
1964 Allice Chalmers D15 tractor
2014 Kubota L3800 tractor
1964 VW bug

"Lifes too short to drive a boring car"

Ok, i drained the res to MC pipe, replaced, filled, removed the SC inlet, no fluid drained out, so i had assistant pump the pedal while i plugged and unplugged the line, finally fluid came out, i took the fluid-filled slave and bolted the line, went to bolt it to the trans and the piston would not go in at all. So the system is blocked somewhere? I haven't adjusted the pedal free play, i'll try this next in case it can only bleed back when fully released (and is not presently).

The later (off set bolt holes) slave looks to have a push rod thats about an inch or so LONGER than the early slave. Seems that would produce a problem just reverse of what you have. Just order a new slave and be done with it, probably not much over $60, you dont want to do this job too many more times

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1985 Euro 240D 5 spd 140K
1979 240D 5 spd, 40K on engine rebuild
1994 Dodge/Cummins, 5 spd, 121K
1964 Allice Chalmers D15 tractor
2014 Kubota L3800 tractor
1964 VW bug

"Lifes too short to drive a boring car"

I guess we're all agreed - you must get the correct slave

Right. If the piston will not go in, the M/C rod is not fully out with free play. (reset the play) If you bought a M/C from MB agent it is for both 123 and 126 cars and should have 2 rods in the kit, the one with the black nylon end is for the 126 and the white nylon end the 123. They are different lengths.

If in doubt use your old rod.

Avoid pumping the pedal at any stage until you are finished. When you have set the free play refill the brake M/C reservoir and disconnect at the S/C.

Wait until fuel is flowing out by gravity from the S/C end - it could take about 5 mins to come through.

Then connect the pipe to the fully bled slave before you bolt it back on. The rod will be fully extended and will push in as you bolt it on. Do not loosen the slave bleed screw at ANY stage.

N.B. Push the slave piston back in only ONCE as you bolt back on. It is sprung loaded out and if you push in and release, it can suck air past the piston seal.

Let it stand at least 15 min before pumping the pedal slowly.

Top up the M/C and your done.

Well, once again, thanks to the patience of those of you who have experience, i've saved some $$ and gained a better understanding of my car. I'm going to share what i learned in case someone else is in the same predicament i was in. Obviously the best policy is always to replace parts with the real thing and not the cheapest aftermarket. Usually i do, and in this instance it actually did not occur to me when i ordered the parts that i was getting the cheap ones (made in China and Taiwan). While it might have been better to send the parts back (both needed altering), i have always loved creative solutions, and enjoy trying to imagine how a third-world mechanic would work, i.e. this isn't the right part but i can't get the right part, how can i make this work?
After removing the slave one more time, i realized that in addition to the bolt pattern being different, by golly, the push-rod was in fact longer. The piston, however, was identical-i measured them with a digital caliper. And of course, it was the ring on the old piston that was not sealing. So, my newly rebuilt slave has: Original housing, new spring, new piston, original push-rod and boot.
The replacement MC looked the same as the original when i first held them up, but after a closer inspection i see that the original had a deeper seat for the pushrod. So what do you think i did? Measured the difference and ground down the push-rod, of course.
One more thing i learned and then i'll shut up. Despite Beagle's advice to just let the fluid drain to the slave inlet pipe in it's own time, i decided to hook the other slave (the parts i was not reinstalling) to the pipe with the bleed screw removed and use it as a suction pump. I uncovered the bleed hole, pushed the rod gently down, plugged the hole and let slave suck the fluid down. A few repeats of this process and the fluid was flowing out.
So there's the happy ending, thanks again y'all!

Aaron

This solution should give you reasonably good service. In the old days I rebuilt many mc for brakes but now the rebuilt unit is nearly the same price so I just buy the whole thing. This is just like buying a kit to do the job. Although the bore will be worn it still should work for a good while.

Some of the nasty pitted bores I got to work because there simply was no replacement available (but a kit was) I would never have believed would work, but they did!

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

I'm pleased to hear you have been successful. You are the first here, AFAIK, to have used this method although I first described this technique here a number of years ago.

I guess that I underestimated the time it would take to flow through at 5 mins - perhaps half an hour would have been more realistic with that small bleed hole. When I changed my M/C I had already changed the S/C a few weeks earlier and let it stand for maybe a hour or more while I did something else.

Anyway that was a smart idea of yours to speed things up.

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Beagle