Hello! I have had my 1983 300D for 2 years now, but I've had a worsening transmission issue since my first drives in the wintertime. My issue first started in December of 2021, when it got to about 35F as a low in the mornings. Shifted fine from 1-2 and 2-3 but 3-4 would have a consistent slip/grab feeling until I let off the throttle, and then it fixed itself for the day. This happened without worsening until it got warmer in the spring, and it didn't happen again until November of 2022. The problem began to get significantly worse as the winter has progressed, and for the first 15-20 minutes of driving after the engine is cold, my 3-4 shift has a strange slipping pattern that gets worse with throttle, and 2-3 also acts up early in the first drive when cold.

I feel like this isn't the traditional "slipping" that is described in auto transmissions, especially since it goes away until the engine goes cold again after I have driven for a bit

See attached video of the tachometer readings while this slipping happens

https://youtu.be/FmoJdG2BEOw

Any advice would be appreciated. Thanks!

First and foremost, I would drain the transmission fluid, Change the transmission fluid filter, and refill with the correct amount of Dexron III transmission fluid. Could be as simple as low fluid, or the incorrect type of fluid.

If after doing that t still acts up, let us know and we can go from there.....

__________________
2012 Mercedes ML350 Bluetec 102K (hers)
2005 Corvette 55K (fun car)
2002 VW Jetta TDI 238K (mine)
1998 Volvo S70 T5 Turbo 211K (kids)
1994 Ford F150 4WD 246K (firewood hauler)
1983 Mercedes 300D 384K (diesel commuter)

My '87 SDL was doing the same thing. Flare between 3-4 shifts while cold. It has 170K. I hadn't changed the fluid in the past 30k, who knows when the previous owner changed the fluid. Filter and fluid change resolved the flare between shifts.

__________________
--------------------------------------------
Old Blue - '83 240D 6 speed manual trans, OM648
Green Machine - 2001 Europa G500
'87 300SDL Bought on Peachparts
'02 E320 4matic wagon

Patchouli Wagon - 2004 E500 - SOLD
333k mile 97 BMW 750il V12. - SOLD
The Californian - 85 300TD - SOLD
Daily Super Sedan - 03 Audi S8 - SOLD
Family Truckster - 2012 VW Touareg TDI - SOLD

Dexron III is obsolete and unlikely to be an option. So you will have to settle for a Dexron III equivalent. I recommend Valvoline Maxlife Multi-Vehicle ATF.

__________________
When cryptography is outlawed, bayl bhgynjf jvyy unir cevinpl.

True, I have found Dexron III from time to time but it is pretty much gone by the wayside. I too have used Valvoline Max life with good results.

__________________
2012 Mercedes ML350 Bluetec 102K (hers)
2005 Corvette 55K (fun car)
2002 VW Jetta TDI 238K (mine)
1998 Volvo S70 T5 Turbo 211K (kids)
1994 Ford F150 4WD 246K (firewood hauler)
1983 Mercedes 300D 384K (diesel commuter)

Transmission treatment might recondition the old seals. Have to drive the car at least a thousand miles to see if it does sometimes.

Recently I found Dexron III in Walmart of all places, where I have bought it as well as Castrol motor oil synthetic blend for quite a few years now. Ditto on Sun Valley, the best in the country and reasonable. Two months ago they rebuilt my 45-year old 722.112, $2500 including shipping both ways.

__________________

Don't Chrome them; polish them

Dexron IIi stopped being licensed long ago. Dexron VI is the new licensed product, and, is a lower viscosity product. GM claims it is backwards compatible, though there were some claims of incompatibility with certain older transmission materials.

Dexron VI and Maxlife are both low viscosity fluids. Our ATs were designed for higher viscosity.

The best modern alternatives are the Allison transmission fluids. I believe TES 295 is equivalent to Dexron IIIH but that would need to be verified as I’m not 100%.

Lubeguard red works well in the MB transmissions too…

__________________
Current Diesels:
1981 240D (73K)
1982 300CD (169k)
1985 190D (169k)
1991 350SD (116k)
1991 350SD (206k)
1991 300D (228k)
2008 ML320 CDI (199k)
1996 Dodge Ram CTD (442k)
1996 Dodge Ram CTD (267k)

Past Diesels:
1983 300D (228K), 1985 300D (233K), 1993 300D 2.5T (338k), 1993 300SD (291k)

Given that the original complaint here was "transmission acting up while cold," a lower viscosity ATF might be just what the doctor ordered.

In any case, I am completely satisfied with the way my transmission performs with Valvoline MaxLife ATF. 1982 300D. I have owned it for 31 years and the transmission has never performed better than it has since I switched to MaxLife six years ago. (Prior to that, I had minor cold temp issues as well.)

__________________
When cryptography is outlawed, bayl bhgynjf jvyy unir cevinpl.

All of the above, new filter, good fluid, drain the converter and go from there. I'd also add Lubegard additive to the service.

It sounds like a valve is sticky and/or the internal seals are hard from age and when it warms they become more pliable.

If you need a transmission Sun Valley in CA is really good.

Good luck!!!

__________________
"Rudeness is a weak man's imitation of strength" - Eric Hoffer

Thank you all for your replies. I will order the transmission filter and fluid and report whether it fixes the issue.

Remember to drain the torque converter as well when you do the fluid and filter change.

__________________
RRGrassi


70's Southern Pacific #5608 Fairmont A-4 MOW car

13 VW JSW 2.0 TDI 193K, Tuned with DPF and EGR Delete.

99 W210 E300 Turbo Diesel, chipped, DPF/Converter Delete. Still needs EGR Delete, 232K

90 Dodge D250 5.9 Cummins/5 speed. 400K

Gone and still missed...1982 w123 300D, 1991 w124 300D

That symptom you describe is called 'flaring' .

As mentioned the trannys and filter plus torque converter must be changed out before anything else .

There's a product called "Trans-X" that an older member here suggested to me long ago, it helped my '82 240D's ailing tranny survive a few more years until I had it rebuilt ~ I used the YELLOW bottle Trans-X, it slowed the ATF drip from the tranny's front seal too .

ADDRESS THIS NOW before you ruin the tranny waiting for warmer weather ! .

What does the ATF on the end of the dip stick look and smell like ? .

__________________
-Nate
1982 240D 408,XXX miles
Ignorance is the mother of suspicion and fear is the father

I did then what I knew how to do ~ now that I know better I do better

I can’t see the speed, so I don’t know what’s right for rpms… but to me it doesn’t look like a flare. Flaring shoukd happen once and then ideally the AT grabs it’s new gear and progresses. This seems all over the place, amd is probably some kind of slipping of the bands due to low pressure or something not right.

A pan drop is in order to see what residues are present.

A flare or single time slip/over speed is one thing. This looks like something worse to me.

__________________
Current Diesels:
1981 240D (73K)
1982 300CD (169k)
1985 190D (169k)
1991 350SD (116k)
1991 350SD (206k)
1991 300D (228k)
2008 ML320 CDI (199k)
1996 Dodge Ram CTD (442k)
1996 Dodge Ram CTD (267k)

Past Diesels:
1983 300D (228K), 1985 300D (233K), 1993 300D 2.5T (338k), 1993 300SD (291k)

Until the filter and T.C. have been serviced there's no point in pondering .

Back when W123's were the in thing for hipsters to have I had similar issues and read endless posts about adjusting and so on, none really fixed the problems until the proper service was done then the pressure check was done, then simple adjustments made everything right again .

__________________
-Nate
1982 240D 408,XXX miles
Ignorance is the mother of suspicion and fear is the father

I did then what I knew how to do ~ now that I know better I do better