hey yellowbenz,

i think 77 is pre bowden, but im not sure.

I do know the haynes will not be helpful here. someone needs to chime in who has some experience with the earlier transmissions.

Ill be watching and ill chime in if I can help.

dd

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'85 300D, 'Lance',250k, ... winter beater (100k on franken-Frybrid 3 Valve Kit)
'82 300D, 'Tex', 228k body / 170k engine ... summer car
'83 300TD Cali Wagon 210k, wife's car

Long time reader first time poster.

Kevin,

I also have a 1978 300D and I am fairly certain that I have a Non-vacuum modulated Trans as well. I found two treads related to the topic.

http://www.peachparts.com/shopforum/showthread.php?t=97353&referrerid=44341

http://www.peachparts.com/shopforum/showthread.php?t=93606&referrerid=44341

Not much to go on but it appears that there is a modulator, also the Haynes guide mentions an adjustment to a connection on the throttle linkage something about a spring and telling the transmission throttle position. When I get my guide back Ill look it up. Some one else on this thread very well may chime in on that before I get the chance though.

My experience has been that when cold the trany shifts a bit firmer, mine is also sensitive to fluid level, If yours has not had a fluid and filter change in a while it really helped mine out.

I drained some fluid out and ran a can of Trans-x for a bout a week then did the filter change and drained the torque converter to. I added a little Lucas trans fluid with the new stuff and it made a big difference in shift quality.

I hope that helps a little bit.
Dory
1979 300D

I know my signature needs updating
Oh and I do not work for Lucas or Trans-x

Thanks, I appreciate the replies. I haven't really paid alot of attention to the posts on auto's because I only owned manuals. When I started to troubleshoot this cars trans issues it became apparent that the posts I'd read didn't really apply to this car apparently.

Kevin
1979 240D manual
1978 300D auto

Good afternoon,

I have come a long way on my car since I first started posting on this thread year ago. I have fixed so many things around the car but the transmission on still no good - and I have a better understanding of what's going on:

Symptoms:
- 1-2 shift slips when accelerating hard, and clunks out of and into gear
- 2-3 is hard
- 3-4 is hard too

Info:
-vacuum signals are correct, above observations come with a lot of vacuum (15mm Hg at idle)
-new modulator is correctly adjusted to 50 psi hydraulic pressure
-fluid and filter done recently

So any idea what to do now? It seems like my system doesn't respond to changing the vacuum all that much. From what I have read over the past year I should be flaring all over the place with 15mmHg at idle. No matter what I do I cant get the other gears to shift mushy.

I am finding myself mentally pricing rebuilt tranny :-(

thanks, dd

__________________
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'85 300D, 'Lance',250k, ... winter beater (100k on franken-Frybrid 3 Valve Kit)
'82 300D, 'Tex', 228k body / 170k engine ... summer car
'83 300TD Cali Wagon 210k, wife's car

You mention....."new modulator"?? Has this been recently replaced?

Dan,
I don't write much on the forum these days... having too much fun actually working our extended family's fleet of 3 MBZ diesels.
Q - Tell us [IF you know]... how many miles on that tranny?
IF you don't know, give us your VIN and # off the tranny and I'll see IF I can verify IF it came with the car.
Now I see... your 82' 300D has 200K+ miles and IF that's the car/tranny and the tranny is original, she might have some life left... but that largely depends upon how much TLC she received over the years!
Regards,

Yes. Modulator and pin behind modulator replaced a year ago, but that less than 1k miles back. It holds vacuum and has the correct pressure set.

__________________
-------------------------------
'85 300D, 'Lance',250k, ... winter beater (100k on franken-Frybrid 3 Valve Kit)
'82 300D, 'Tex', 228k body / 170k engine ... summer car
'83 300TD Cali Wagon 210k, wife's car

I think the tranny has 200k. I have to get down there to get the serial #, but I suspect it to be original.

TLC received - Im pretty sure until I got it, zero :-)

__________________
-------------------------------
'85 300D, 'Lance',250k, ... winter beater (100k on franken-Frybrid 3 Valve Kit)
'82 300D, 'Tex', 228k body / 170k engine ... summer car
'83 300TD Cali Wagon 210k, wife's car

My 85 Diesel Turbo shifts from 2-3 really hard, like slamming into the gear.
What should I be checking??Do you guys have any pics??
I'm kinda confused because I have read all kinds of things!
Where to start?

__________________
DOMAIN NAMES FOR SALE:
www.diesel911.com
www.dieselbenz.com
www.dieseldoctor.biz
Please PM me with offers.

Why not reduce modulator pressure a bit..........if you've got no flaring...........and see how it performs?

Thanks Brian...Ill give it a try.

What I do have is slipping between 1-2 under hard accel.

dd

__________________
-------------------------------
'85 300D, 'Lance',250k, ... winter beater (100k on franken-Frybrid 3 Valve Kit)
'82 300D, 'Tex', 228k body / 170k engine ... summer car
'83 300TD Cali Wagon 210k, wife's car

When you say "slipping" do you actually mean "flaring"??

As the Bloke who started this long THREAD I still need to know:
So:
Q1 - Do you have a vacuum gauge?
Q2 - What is the vacuum at the "T" that branches off to the Engine/Tranny control system... branches off the main Vacuum Pump -to- Brake booster reservoir chamber?
Q3 - Have you checked the vacuum line and fittings on your engine/tranny vacuum control system?
Q4 - What about the other vacuum using systems/components... done any checking for leaks?

Unless you have a California 1985 "300DT", the correct vacuum control diagram for it is: http://www.peterschmid.com/vacuum/1977_1985/617_95/1984_1985.jpg

These are touchy control systems and yours is a later model vintage car so the controls are a bit more complicated. I just hope you don't have a CALIF car.

Q5 - What's the VIN off your car?

Regards,

Well Im fuzzy on the difference between the two...heres what happens...

- accel hard
- goes to shift to second, feel the trans disengage gears hard, feels kind of like it has shifted to second (NOT soft or mushy), but RPMs dont decrease
- keeps moving through the accel fine, rpms dont rev high like a flare or bad slip
-once rpms come down from the hard accel, finishes the shift (hard) into second (again, NOT soft or mushy)

This gap in time last as long as the engine stay above 2.5k rpms or so.

A flare i've taken as means when the rpms hugely rev like on a standard when the clutch is going, an the subsequent shifting isnt hard but mushy.

whatever it is, the symptoms have me confused - they dont match anything Ive seen reported in my now extensive reading on the subject here.

dd

__________________
-------------------------------
'85 300D, 'Lance',250k, ... winter beater (100k on franken-Frybrid 3 Valve Kit)
'82 300D, 'Tex', 228k body / 170k engine ... summer car
'83 300TD Cali Wagon 210k, wife's car

You've definitely got some confusion here.

Flaring requires the transmission to let go of the lower gear and fail to engage the higher gear..........as if it's gone to neutral between gears..........the tach climbs dramatically and the driver instinctively lifts the pedal...........and it upshifts.

One rather unique characteristic of these automatics is the tendency for the tach to remain at a given engine speed during mid power shifts. I cannot explain it, but have observed similar behavior on these. You accelerate at 2500 rpm in first and the tach doesn't drop on the 1-2 shift, although you could swear that the engine drops in revs.

When you notice the shift..........I'll bet the 1-2 has been completed a long time ago and you are now observing the 2-3 shift. It's not possible for the transmission to hang up between two gears unless it flares (as defined above).

So, kindly check again. See if you're confusing proper 1-2 and 2-3 shifts with a "slip" that you've identified as a 1-2.