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.....

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2012 Mercedes ML350 Bluetec 91K (hers)
2005 Corvette 55K (fun car)
2002 VW Jetta TDI 231K (mine)
1998 Volvo S70 T5 Turbo 196K (kids)
1994 Ford F150 4WD 249K (firewood hauler)
1983 Mercedes 300D 376K (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.

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Old Blue - 83 240D 6 speed manual trans, OM648
Green Machine - 2001 Europa G500
87 300SDL Bought on Peachparts. Low-ish miles..?

Family Truckster - 2012 VW Touareg TDI

Patchouli Wagon - 2004 E500 - SOLD
333k mile 97 BMW 750il V12. - SOLD
The Californian - 85 300TD - SOLD
Daily Super Sedan - 03 Audi S8 -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Dexron III is obsolete and unlikely to be an option.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.

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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!!!

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

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.

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2012 Mercedes ML350 Bluetec 91K (hers)
2005 Corvette 55K (fun car)
2002 VW Jetta TDI 231K (mine)
1998 Volvo S70 T5 Turbo 196K (kids)
1994 Ford F150 4WD 249K (firewood hauler)
1983 Mercedes 300D 376K (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.

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Don't Chrome them; polish them

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

I suspect that what you found was a Dexron III equivalent. All licenses to manufacture Dexron III expired over 15 years ago.

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When cryptography is outlawed, bayl bhgynjf jvyy unir cevinpl.

I can't speak to the issue of "equivalent", but what I have been using for years is Dexron III by Valvoline.

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Don't Chrome them; polish them

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

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RRGrassi


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

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

91 W124 300D Turbo replaced, Pressure W/G actuator installed. 210K

90 Dodge D250 5.9 Cummins/5 speed. 400K

My bookie is laying 10:1 odds that you are using an equivalent but you just don't realize it. Dexron III licenses expired in 2006, so there is absolutely no way that Valvoline is currently producing a product labeled "Dexron III."
Kindly note that names like "Dex/Merc" is different than "Dexron III." "Dexron" is a GM trademark which can be used by third parties ONLY under license.

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When cryptography is outlawed, bayl bhgynjf jvyy unir cevinpl.

Noted and kudos to your bookie. Yes, it's DexMerc, which is recommended for replacing Dexron III. In addition, Marc at Sun Valley Mercedes just told me that he agrees, DexMerc is fine to use.

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Don't Chrome them; polish them

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 ? .

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-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