300TD wagon manual trans shifting problem- ideas? - PeachParts Mercedes-Benz Forum

moorerp · #1 12-05-2009, 01:47 PM

Hi All,

My manual 4-speed '83 300TD wagon is experiencingshifting issues. It started out just being difficult to get into 1st gear while the engine was running, not so bad with the other gears. I basically had to force it into first, though there's usually no grinding sounds unless I'm trying to get into reverse, in which case there's continuous grinding (of the gears and my teeth).

It has now progressed pretty quickly to difficult to get into most gears and impossible to get into reverse when the engine is cold, improving noticeably after driving for about 30 miles (but still not perfect). There is now obvious "creep" on startup, meaning the clutch is obviously not disengaging completely when the clutch pedal is depressed. I won't be able to drive it all soon (although presently, if I need reverse, I just turn the engine off, put it in reverse, and then restart with the clutch in. Not exactly a long-term solution).

Any ideas on diagnosis would be greatly appreciated. I'd love for it to be a hydraulic problem and not a clutch guts problem, but I have no clue.

thanks,
Randy

kerry · #2 12-05-2009, 02:05 PM

It's most likely a problem either in the clutch master or slave cylinder. If pumping the clutch pedal a number of times makes the problem disappear it is almost certainly a problem in one of those components.

Diesel911 · #3 12-05-2009, 02:11 PM

Quote:

Originally Posted by moorerp

Hi All,

My manual 4-speed '83 300TD wagon is experiencingshifting issues. It started out just being difficult to get into 1st gear while the engine was running, not so bad with the other gears. I basically had to force it into first, though there's usually no grinding sounds unless I'm trying to get into reverse, in which case there's continuous grinding (of the gears and my teeth).

It has now progressed pretty quickly to difficult to get into most gears and impossible to get into reverse when the engine is cold, improving noticeably after driving for about 30 miles (but still not perfect). There is now obvious "creep" on startup, meaning the clutch is obviously not disengaging completely when the clutch pedal is depressed. I won't be able to drive it all soon (although presently, if I need reverse, I just turn the engine off, put it in reverse, and then restart with the clutch in. Not exactly a long-term solution).

Any ideas on diagnosis would be greatly appreciated. I'd love for it to be a hydraulic problem and not a clutch guts problem, but I have no clue.

thanks,
Randy

Looks like you diagnosed they problem already. Clutch not disengaging properly.

moorerp · #4 12-07-2009, 04:25 AM

Quote:

Originally Posted by Diesel911

Looks like you diagnosed they problem already. Clutch not disengaging properly.

Right-o, but the problem is that I don't know whether that means the clutch mechanism itself is toast (knock-on-wood) or whether the mechanism that disengages the clutch (the hydraulics, in my limited undertstanding of what's going on) is toast (ojala!).

I was kinda hoping someone would see the symptoms and be able to jump in and say "you idiot, that's obviously a slave cylinder problem," but perhaps it's not so simple as all that?

cheers,
r

t walgamuth · #5 12-07-2009, 05:56 AM

It is almost certainly a slave or clutch master problem. Have you made sure your brake fluid is full?

lutzTD · #6 12-07-2009, 08:50 AM

generally a worn clutch loses reverse then first. But it could also be one of the hydraulic cylinders. There is a tool you can make to check clutch wear, someone here will chime in with a picture.

edit: see post #3 here

kerry · #7 12-07-2009, 09:33 AM

Quote:

Originally Posted by moorerp

Right-o, but the problem is that I don't know whether that means the clutch mechanism itself is toast (knock-on-wood) or whether the mechanism that disengages the clutch (the hydraulics, in my limited undertstanding of what's going on) is toast (ojala!).

I was kinda hoping someone would see the symptoms and be able to jump in and say "you idiot, that's obviously a slave cylinder problem," but perhaps it's not so simple as all that?

cheers,
r

Did you try pumping the clutch to see if the symptoms disappear?

JEBalles · #8 12-07-2009, 03:43 PM

Definitely clutch problem. My bet's on the slave, but check both for leaks and check your fluid level. It's probably one or the other.

winmutt · #9 12-07-2009, 03:59 PM

Collapsed or leaking hose might be something to look at to.

moorerp · #10 12-10-2009, 03:44 AM

Thanks for the input folks- The fluid level in the resevoir is good, so nothing as easy as burping the air out of the system, unfortunately. Pumping the pedal doesn't seem to do anything at all to improve things.

So next question- since no 300TD's for the American market had manual transmissions, which master and slave cylinders do I get for my '83 300TD (non-turbo)? Are the 240D master and slave (which are available online) different than those that would be used for the standard in-line 5 cyl. that's in the Beluga?

kerry · #11 12-10-2009, 09:51 AM

I'm guessing they're all the same but if pumping the pedal doesn't improve the situation, I don't think that replacing master and slave will resolve the problem. On some slaves, there is an adjustment on the actuating rod. Don't know if MB's have it but I would certainly look because it sounds as if you are not getting enough travel out of that rod. Lengthening the rod should give you more travel and a full release of the clutch.

charmalu · #12 12-10-2009, 11:33 PM

I know there is a difference when ordering slave, master and release
bearing. I think the older iron boxes use a different part # than the later
all one piece aluminium box.

I know when I ordered my parts when I did the trans swap, it`s listed for
chassis# XXXX for one group, and after chassis# XXXX for the later parts.

Look under your TD and see what type tran you have.

Charlie

johnjzjz · #13 12-11-2009, 08:28 AM

when a master starts to go away ( bypassing fluid ) usually what happens is the travel of the slave cylinder becomes liminated -meaning it ( the slave ) does not extend as far as it should, this causes the clutch to act as if you put a block under the clutch pedel and limit the throw --

if you unbolt and with out removing the lines, slide out the clutch master, look behind it you may notice it seems wet even tho your resv is full < bypassing fluid - not every time but most of the time you will find this ( a small fluid loss )

if a slave goes bad it normally will leak fluid out ( 99% of the time ) of the boot causing the same problem but with fluid loss

change them both - fresh fluid in an old slave most times will start leaking soon after a master replacement - jz

Stevo · #14 12-11-2009, 11:11 AM

First thing I would do is pull the carpet down up under the pedal assembly and feel for wetness on the hard line from the clutch master and if its been leaking for a while there will be brake fluid under the carpet. I'm sure you already know this but I gota ask anyway, the brake master has two chambers and the fluid in the rear one is often very hard to see, which is the one for the clutch, you know this chamber is full?