clutch problem 240D - PeachParts Mercedes-Benz Forum

clanreed · #1 07-06-2013, 05:57 PM

I have a 1977 Mercedes 240D manual transmission car that my son has been driving for the past year. He was out driving went around a corner and there was no clutch. The car was towed home.

I am unsure of the mileage on the clutch. As far as I know, it did not slip or have any precursors that would have led us to believe the clutch was going bad. I pulled the slave cylinder and the diaphragm was bad, so I replaced it with a new slave cylinder. I also replaced the clutch master cylinder because it was leaking. I used the original push rod on the new master cylinder. Then I spent a very long, long time bleeding the clutch. Finally after bleeding the clutch with a pressure bleeder from the top of the reservoir I was able to get good pressure on the clutch and the peddle returns on its own.

Here is where I am at now:
*If the car is not running, I can move it into any gear without using the clutch peddle
*If I start the car not in gear, I cannot move it into any gear even with the clutch peddle depressed--lots of grinding.
*If I start the car in gear, in lunges forward as though I have popped the clutch.

I am a learn as I go mechanic, but a new clutch may be out of my skill set if that is the problem. The value and condition of the car make a $1000 clutch job probably not a good investment. I just want to make sure I have tried everything before I give up on the car. If anyone has any ideas of something I may be missing or something to try let me know.

Thanks,
Shannon

charmalu · #2 07-06-2013, 06:30 PM

First of all................Welcome to the Forum.

Bleeding the Clutch has to be from the bottom up, IE from the Slave Cylinder.
The Factory Shop manual (FSM) states to connect a hose from the R/F Caliper bleed Nipple over to the Slave Bleed Nipple.

Open the Nipples, and pump the Brake Peddle. (Do not pump the Clutch peddle) you are cycling the fluid from the Reservoir, to the R/F Caliper, thru the Slave Cylinder and MC and back to the Reservoir . This pushes the air up, air just does not want to go down for some reason.

Another way is to use a clean Oil Pump can, fill it with Brake Fluid, connect it to the Slave Cylinder and pump away.
here is a good video explaining it.
BMW, VW, Porsche Clutch Bleeding - YouTube

Bottom line is, you probably still have air in the system. you are not the only one pulling your hair out, there are a lot of bald headed guys that have come before you.

The Clutch (if you need one) is not all that difficult to DIY.

PeachPartsWiki: Clutch R&R

I know the 4-Spd trans on the 82 & 83 240D weighs 54lbs. Its an all one piece aluminum case. your 77 thru 81 is the two piece, with the iron box and the separate aluminum, Bell Housing. it weighs just a bit more. not all that difficult to DIY at home in the driveway/garage.
I swapped out the auto trans in our 85 for a 240D 4-spd here at home. Noot that big of a deal.

\This would be a good learning experience for your son, and he might have more respect for his car, that now he can say "I did that".

Post where you live and maybe a Forum member is some where close by that has done this before and will lend a hand.

Charlie

kerry · #3 07-06-2013, 06:39 PM

If you pump the clutch like hell, 8 or 10 times quickly, will it work? If so, the problem is an unbled clutch.

I believe there is one instance recorded on the forum of the clutch fork breaking. That also might be the cause of your difficulty.

Stevo · #4 07-07-2013, 09:30 AM

The job of bleeding the clutch is not difficult if you use the squirt can. The hardest part might be finding a decent squirt can, as the chepo I got at Harbor Freight leaked. I have three manual 123s and so I've had allot of practice bleeding clutches. The brake slave to clutch slave method is a pain as the two nipples are different sizes. There are several reasons to forget that method. The squirt can generally has the same size end as the slave nipple so get some clear hose at the hardware store that fits tight on both. Pull fluid out of the brake reservoir using a turkey baster so it doesn't over flow when you pump fluid up. fill the squirt can, hold the hose up, gently squeeze the pump trigger and get the air out of the hose, now attach the other end to the clutch slave nipple, open it and pump. When your assistant sees only clear fluid coming into the reservoir, close the nipple, your done...not a big deal if you have a squirt can and some hose. If the fluid leaks a little around the nipple put a some Teflon tape on the threads. Also if you put the box end of the wrench (7mm) over the nipple before the hose it wont keep falling off. Theres a recent clutch bleeding post where the guy used a large syringe, a new, clean grease gun would probably work also.

charmalu · #5 07-09-2013, 12:34 PM

So what is the verdict on your 240D?

Charlie

clanreed · #6 07-11-2013, 12:48 PM

I did forget to mention that I first tried both bleeding from the caliper and the oil can method before pressure bleeding from the top. I am going to try again though this weekend (I have been busy getting the air conditioning running on our '82 300D turbo, so the clutch problem moved down the list). I am searching for a better oil can as mine was a cheapo that leaks under pressure. I will post the results.

Quote:

If you pump the clutch like hell, 8 or 10 times quickly, will it work? If so, the problem is an unbled clutch.

This didn't work for me.

Quote:

I know the 4-Spd trans on the 82 & 83 240D weighs 54lbs. Its an all one piece aluminum case. your 77 thru 81 is the two piece, with the iron box and the separate aluminum, Bell Housing. it weighs just a bit more. not all that difficult to DIY at home in the driveway/garage.

I have been researching doing this myself and my husband is usually willing to help with the heavy lifting part, so maybe....

Shannon

zeke · #7 07-11-2013, 02:48 PM

Had the same thing happen to us last fall. Tried to bleed from the bottom, then tried the oil can method (waaaaay better, for sure!). Neither worked.

Replaced the clutch master and slave cylinders, bled with the oil can method, and the problem is fixed.

In my case, the clutch would lose pressure when the RPMs went up high. Never completely figured it out, but I think that there were microperforations in the flywheel-side boot of the slave and the vibration/heat when the engine revved led to introduction of air. There were no leaks visible, and the boot was pretty clean, though dry-rotted.

winmutt · #8 07-11-2013, 03:55 PM

Chicks who know how to bleed clutches. WIN

Dan Stokes · #9 07-11-2013, 05:40 PM

Shannon - check my thread ("I'm Back, ......."). I just reinstalled the clutch on my OM617 and took step-by-step pics of the deal. I should have it up in a few minutes. This ignores actually removing the trans as mine is currently on the bench but it should give you a good look at the actual clutch procedures.

Dan

47dodge · #10 07-11-2013, 06:50 PM

Your problem is not the clutch slipping, from what you describe it is not disengaging. So replacing the clutch will not help. As most have said you need to bleed it. Once this problem is solved then you can check for clutch slipping. I do not expect that to be a problem though, if it was not before this happened.

Dan Stokes · #11 07-11-2013, 08:43 PM

I think you're probably right but I had these pics and thought they might help in building an understanding of the clutch system.

The 240D I got the clutch out of had a bad (pretty much un-bleedable) slave so I just bought a new one rather than mess with rebuilding it. No reason to think that this one needs a master - each car is an individual.

Dan

clanreed · #12 07-14-2013, 10:33 AM

So after an exhaustive search for a quality oil can, I did find one. I bled the clutch again using the oil can method through the slave cylinder. There is no change--I still have good feel from the clutch peddle and it returns on its own. The symptoms are the same--

Quote:

*If the car is not running, I can move it into any gear without using the clutch peddle
*If I start the car not in gear, I cannot move it into any gear even with the clutch peddle depressed--lots of grinding.
*If I start the car in gear, in lunges forward as though I have popped the clutch.

The only new symptom is the dash brake light is continuously on. This may have been on previously without me noticing as I did have the emergency brake engaged and attributed the light to that.

Quote:

Your problem is not the clutch slipping, from what you describe it is not disengaging.

Yes, I do think the "not disengaging" is correct. Assuming the clutch is properly bled, what should I be looking for as the problem?

Is there anything else that can be checked before disassembling the clutch?

I am looking for a diagram or explanation that will show exactly how the entire "clutch system" works. I push in the clutch, engaging the master cylinder, hydraulic pressure pushes the rod out of the slave cylinder, ...

Quote:

Shannon - check my thread ("I'm Back, ......."). I just reinstalled the clutch on my OM617 and took step-by-step pics of the deal.

Dan Stokes thanks for the great information. It definitely got me thinking, maybe...

Thanks,
Shannon

Stevo · #13 07-14-2013, 02:57 PM

Well now you have done what you could to dismiss the easy stuff and when you reinstall your tranny and new clutch assembly , you'll have the right equipment to bleed it. Its not often something goes wrong as you described but you needed to be sure its not the hydraulics before pulling the tranny. Its a relatively easy job on a 240D tho.

sassparilla_kid · #14 07-15-2013, 12:00 AM

So I'm having pretty much the same problem on my 300D that I just swapped the manual into, I have tried every method of bleeding, from the brake caliper method to the oil can method to bleeding like you would brakes, and none have worked. I have a new slave cylinder ordered so I'm hoping it is some kind of mysterious problem with the old one because I just don't understand it. Luckily if I pump the pedal a bunch of times it kind of lets me shift into first, so I have gotten fairly decent at rev matching and shifting without the clutch. The strange thing is sometimes the pedal stays down, sometimes it doesn't, sometimes it just sucks down to the floor for no reason. So frustrating

woodrat · #15 07-15-2013, 01:34 AM

Quote:

Originally Posted by clanreed

Yes, I do think the "not disengaging" is correct. Assuming the clutch is properly bled, what should I be looking for as the problem?

Is there anything else that can be checked before disassembling the clutch?

I have exactly the same car, and have had exactly the same clutch frustrations. What to look for? Brake fluid on the master cylinder behind the boot, showing leakage there, and in the same place on the slave. What you're describing is far more likely to be a hydraulic system problem than the need for a new clutch.

I had one master cylinder go bad in a matter of months after replacing it, for reasons I still do not understand. But it WAS wet, and definitely was leaking. So, I replaced it, this is after previously also replacing the slave, bled from the RF caliper upwards, car worked great for a while, then went back to not working. I finally parked it in frustration, but just the other day fired it back up to work on it, and the clutch seems to work fine.... (!!!???)

The car was parked on a side slope that had the left side of the car several inches higher than the right side for about four months. I have to wonder if some trapped air bubble slowly worked itself out of there... ?

Anyway, I'm back to trying to make this car operable again this week, and will be hoping that my "slope/air bubble" theory is somehow valid, or at least that I have better luck bleeding the system next time around...