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  #1  
Old 04-26-2011, 11:10 PM
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1983 300D Questions

I recently purchased a 1983 300d with 230k miles on the odometer. Several obvious issues existed with the vehicle that I would like to fix as soon as possible. After spending quite a few hours reading and researching the issues I wanted to ask several questions before proceeding with repairs.

Transmission:
  • seems to shift normally when accelerating, but clunks really hard when braking and coming to a stop and the transmission is working back to first gear
  • believe this is from a vacuum issue, most likely the vacuum modulator
  • checked vacuum (on the line above) with a hand pump and discovered the modulator leaks down (to zero) within 5 seconds
  • can the modulator be removed from the transmission without removing the transmission? Things seem really tight and I can not even tell how the modulator is mounted.
  • I would like to remove the modulator (how much should this part cost?) to test and any help on describing the removal would be appreciated
  • Is there a vacuum diagram available for a 1983 300d?
Torque converter:
  • Please see the attached picture
  • Is this window in the torque converter normal or is something broken?
Loose red wire:
  • Please see picture
  • There is a red wire with an inline fuse that enters the engine compartment through the firewall on the drivers side.
  • Wire is not connected to anything and just hanging
  • What is this wire for and where should it be connected?
Thanks in advance for helping out a new owner of a 123 300D! I am excited to get this thing into daily driver shape.

Attached Thumbnails
1983 300D Questions-300d-red-wire.jpg   1983 300D Questions-transmission.jpg  
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  #2  
Old 04-27-2011, 12:08 AM
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The modulator bleeding down like that is not normal. However, the usual mode of failure is for the diaphragm inside to rupture. This results in transmission fluid being sucked into the vacuum line. How exactly were you connecting the hand pump to get a reading off the modulator? I'm suspecting that there may be a leak in the line or at the banjo bolt*. I also think in spite of the leakage that your modulator is probably still working somewhat close to right. If it wasn't you'd be getting very late harsh upshifts while accelerating.

You might also want to look at your transmission mount and the flex discs in the drive shaft. When these things go bad they can cause clunking and things with even a smoother than average transmission.

If your modulator does turn out to be bad, this site lists two different ones for around forty dollars each. I'm not sure of the attachment method, since the ones for the 722 look radically different than the one that I changed in my '71. I'm going to take a somewhat educated guess that it can be changed without pulling the transmission.

Vacuum diagrams here: http://www.peachparts.com//shopforum/showthread.php?t=295616&highlight=vacuum

*I'm basing most of this on the transmission in my '71. I never really messed with the automatic my '83 came with. Once it gave me an excuse, I swapped it for a manual.
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Whoever said there's nothing more expensive than a cheap Mercedes never had a cheap Jaguar.

83 300D Turbo with manual conversion, early W126 vented front rotors and H4 headlights 400,xxx miles
08 Suzuki GSX-R600 M4 Slip-on 22,xxx miles
88 Jaguar XJS V12 94,xxx miles. Work in progress.
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  #3  
Old 04-27-2011, 09:23 AM
vstech's Avatar
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as to the pics. it looks like your bellhousing has taken a hit to me. I doubt it's anything to worry about.
the red wire must be for something a previous owner installed then removed.
remove the wire or use it for a spare 12v socket in the car!
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"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
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1987 190D 2.5Turbo
1987 190D 2.5-5SPEED!!!

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  #4  
Old 04-27-2011, 10:59 AM
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Quote:
Originally Posted by skibummer View Post
I recently purchased a 1983 300d


... There is a red wire with an inline fuse that enters the engine compartment through the firewall on the drivers side.
  • Wire is not connected to anything and just hanging
  • What is this wire for and where should it be connected?
I had an '82 240d (now departed) with a similar "add on" inline fuse running out of the main fuse box. I was told (on another list), when I asked a similar question to yours, that it was a Mercedes update campaign for w123s when the cars were almost new.

Sorry but that is the extent of my memory retention on that one (was five years ago).
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2002 e320 4matic estate│1985 300d│1980 300td
Previous: 1979 & 1982 & 1983 300sd │ 1982 240d

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  #5  
Old 04-27-2011, 11:04 AM
vstech's Avatar
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Hmm.
I know about the blower fuse update. but it would be in and out of the fuse box, not into the firewall.
__________________
John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 190D 2.5Turbo
1987 190D 2.5-5SPEED!!!

1987 300TD
1987 300TD
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!
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  #6  
Old 04-27-2011, 02:47 PM
Yak Yak is offline
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Quote:
Originally Posted by skibummer View Post
I recently purchased a 1983 300d with 230k miles on the odometer. Several obvious issues existed with the vehicle that I would like to fix as soon as possible. After spending quite a few hours reading and researching the issues I wanted to ask several questions before proceeding with repairs.

Transmission:
  • seems to shift normally when accelerating, but clunks really hard when braking and coming to a stop and the transmission is working back to first gear
  • believe this is from a vacuum issue, most likely the vacuum modulator
  • checked vacuum (on the line above) with a hand pump and discovered the modulator leaks down (to zero) within 5 seconds
  • can the modulator be removed from the transmission without removing the transmission? Things seem really tight and I can not even tell how the modulator is mounted.
  • I would like to remove the modulator (how much should this part cost?) to test and any help on describing the removal would be appreciated
  • Is there a vacuum diagram available for a 1983 300d?
Torque converter:
  • Please see the attached picture
  • Is this window in the torque converter normal or is something broken?
Loose red wire:
  • Please see picture
  • There is a red wire with an inline fuse that enters the engine compartment through the firewall on the drivers side.
  • Wire is not connected to anything and just hanging
  • What is this wire for and where should it be connected?
Thanks in advance for helping out a new owner of a 123 300D! I am excited to get this thing into daily driver shape.
Shifting, the tranny and vacuum has it's own (at least one) War and Peace length thread: It's CRITICAL... how you set your transmission's vacuum system on your diesel MBZ...

I'd recommend staying out of that until you establish a baseline on your overall vacuum system. Yes there are diagrams. Since I did one on an '83 300CD, you get the link to mine. Yes, I'm proud of it; but there are others: Definitive '83 Fed 300CD vacuum thread

The grid on your bellhousing has taken a beating. If the tranny is otherwise okay, don't obsess on it. But I would take that as a clue to look around for other undercarriage and/or oil line, oil pan, tranny line, etc damage. The hard lines for the tranny from the cooler and the oil pan itself may be good places to start an inspection.

The wire has to go somewhere. If it's still connected to the battery, I'd remove that end. At the very least remove the fuse in there to open the circuit from the battery(?) to the passenger compartment. You can see up inside the footwell for the other end of the grommet by removing the lower driver's panel (three screws and two plastic "spikes" I think). Wear goggles or 28-year old fluff will get in your eyes. You'll become very good at pulling this panel in short order.
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  #7  
Old 04-28-2011, 12:40 AM
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I was afraid that the bell housing was broken, but couldn't find a picture to compare. After looking around the area for other damage, the only thing obvious is a leak near the front of the transmission/torque converter. Hopefully there is no other hidden damage.

Thanks for the links to the vac diagrams! Awesome information. I have my work cut out for me trying to diagnose any issues. I "rented" a vac pump and begin poking around the system. Any tricks for adapting the pump to all of the different existing vacuum line sizes? I am having trouble getting a good connection to the various sizes.

I think the red wire through the firewall has something to do with the aftermarket radio that is installed. The radio works normally, but when you turn the headlight switch it powers the radio on and off. It completely resets the unit (loses memory).... kinda strange.

Thanks for the great comments, keep them coming.
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  #8  
Old 04-28-2011, 12:40 PM
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Could be as simple as it tipping off a tranny jack and smacking against the floor during a previous transmission R&R, I imagine.
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  #9  
Old 04-28-2011, 08:50 PM
Yak Yak is offline
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Quote:
Originally Posted by skibummer View Post
<>
Thanks for the links to the vac diagrams! Awesome information. I have my work cut out for me trying to diagnose any issues. I "rented" a vac pump and begin poking around the system. Any tricks for adapting the pump to all of the different existing vacuum line sizes? I am having trouble getting a good connection to the various sizes.

I think the red wire through the firewall has something to do with the aftermarket radio that is installed. The radio works normally, but when you turn the headlight switch it powers the radio on and off. It completely resets the unit (loses memory).... kinda strange.

Thanks for the great comments, keep them coming.

For vacuum, divide and conquer. Or figure out what doesn't work, then isolate those systems. The cone-shaped connector on the Mity-Vac worked for most of the rubber connectors. A hand pump can isolate most of the components. Take pictures before disassembly to help with reassembly.

The radio sounds easy: the PO used the gray/violet wire from the dimmer circuit as switched power. As least he didn't ground that one. The gr/vi gets power from the rheostat when the headlights are on and adjusts intensity based on the rheostat.

That may mean the cigarette lighter circuit is messed up, since the OE radio install gets power from there. Plenty of threads on the radio in the media forum.
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  #10  
Old 04-28-2011, 09:48 PM
Craig
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Skibummer, you're not Eric by any chance?
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  #11  
Old 04-29-2011, 01:14 PM
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Quote:
Originally Posted by Orv View Post
Could be as simple as it tipping off a tranny jack and smacking against the floor during a previous transmission R&R, I imagine.

Very true... and I don't see any other damage after having it on ramps last night.
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  #12  
Old 04-29-2011, 01:14 PM
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Quote:
Originally Posted by Craig View Post
Skibummer, you're not Eric by any chance?

Nope... must be another skibummer!
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  #13  
Old 05-09-2011, 10:48 AM
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Transmission will not engage... HELP!

So.... after spending some time with the car and putting over 1000 miles on it, I felt like I was making some progress on the vacuum system and transmission shifting problems... I found that I was not sending any vacuum to the transmission at idle and chased the big leak down to one of the vacuum lines going to the valves on top of the valve cover or in the EGR system. I plugged the line supplying this portion of the system and was getting about 6" of vac to the transmission at idle (still low, but better than before). My shifting was immediately improved, especially the ugly down shift I was getting previously. Then last night the transmission stopped engaging as I was pulling into my driveway (great timing!). I can not get the transmission to engage in any of the forward gears. Reverse seems to engage just fine. While messing around with trying to reconnect vac to the egr and valve cover, the 5 plastic connectors on the top of the valve cover snapped off, so I need to replace that now....

So quick questions... is the tranny shot? did changing the vacuum cause this problem? would plugging the line to the top of the valve cover cause this problem?

Thanks for your help! I am fearing the worst case news....
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  #14  
Old 05-09-2011, 02:19 PM
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Reverse but no forward-someone help me out here, is that the symptom of a failed B2 piston?
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Whoever said there's nothing more expensive than a cheap Mercedes never had a cheap Jaguar.

83 300D Turbo with manual conversion, early W126 vented front rotors and H4 headlights 400,xxx miles
08 Suzuki GSX-R600 M4 Slip-on 22,xxx miles
88 Jaguar XJS V12 94,xxx miles. Work in progress.
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  #15  
Old 05-09-2011, 02:55 PM
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Transmission HELP!

Anybody have any advise? Not sure on the B2 piston, I thought that only affected one forward gear. I should also note that the gear selector will work through all gears, but nothing happens at any of the forward positions.

Thanks!

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