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· Registered
1992 300D, 1999 E320 turbodiesel
14 Posts
Discussion Starter · #1 ·
I would appreciate any suggestions on what might be wrong with my 1992 300D with approx 214k. When the weather turned cold (i.e., <40F), I noticed that the car was delaying shifting upwards (1-->2, 2-->3, etc.), but was fine when it warmed up. It also seemed that if I left it in the garage it would start out shifting reasonably well, but as soon as it got a bit of the cold air around the transmission it started to delay. After about 1-2 miles of driving, the shifting began to improve, and it would become smooth as butter after 4-5 miles.

The gasoline model (300E) has an upshift delay circuit that slows upshifting when it is cold (to warm the catalytic converter), but the diesel has nothing like that. The transmission was rebuilt at 178k, could they have inadvertently installed a 300E transmission?

I recently had the transmission serviced with a complete drain of the fluid and changed the filter, and replaced it with Mobil 1 Dextron fluid. That did not solve the problem. What else could it be? As it is, I can't drive the car in the cold weather (but the turbo works great in the cold).

-Mark HIll

· Registered
2003 w211 E500 Sport
93 Posts

· Registered
1992 300D, 1999 E320 turbodiesel
14 Posts
Discussion Starter · #3 ·
Additional information

There is one odd thing about it that makes me think that it is not somehow in the shifter assembly:

It shifts better when I first drive off from the relative warmth of the garage (40-50F), and once it hits the cold air of 15-30F it become more reluctant to shift until it warms up completely. That suggests that there must be a sensor telling the transmission to delay. But...where is that sensor?

My mechanic seems puzzled by the issue, even though he has been incredibly competent on all other repairs. I hesitate to take the car to the dealer because I do not want to get fleeced (without necessarily fixing the car).

Any other ideas out there?

· Registered
'90 124.128
243 Posts


Input for 722.418
1.RPMs from 602.962
[The 722.4 can't tell "Hot" from "Cold" RPMs]
2.Vacuum from V.P. > "Blue Flying Saucer" (AKA Vacuum Amplifier)V.C.V. > Modulator Valve.
[Vacuum ONLY controls the Soft/Harshness of the SHIFTS.]
3.Accelerator input from the "Bowden" cable.
[Adjusting the cable makes the shift points EARLY or LATE,BUT there's no way COLD could
affect/effect the Cable's length enough to make a difference.]
4.Kickdown Valve.It will "hold" Tranny in gear when BAD.
[NEVER heard of one acting Balky like that (DeLaying UpShifts)due to Ambient Temps]

The Transmission Fluid can take 20 minutes to fully warm up.
[Short Hops, 5-10 miles or less,doth not warm the cockles of the Tranny's heart.]
I'm Crawling out on the limb here...BUT I think you're just getting a pretty much normal reaction from a COLD RADIATOR.
Garage is warmer than Ambient.All fluids are Garage temp.
BUT the engine and Radiator are not at Operating temps YET!
When you roll out of the garage into the colder ambient the Thermostat is CLOSED.
The radiator is sealed off from the engine (So It'll [the Engine] warm quickly) .
The COLD ambient Air outside Chills the Coolant AND THE ATF in the Radiator.
AND Continues to CHILL the ATF until the Thermostat opens.
The Coolant AND THE ATF don't stand a chance of Warming until the Engine reaches Operating Temps and opens the Thermostat.

stevebfl would know for sure.
[Is he over here?]

Screen name on Peach Parts is stevebfl
Post your question over there he'll answer.
Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician


· Registered
91 Benz 300D
341 Posts
Change the fluid and filter :).

When I took ownership of my 91 300D last year it had similar problems. It wouldn't shift out of 1st for a l-o-n-g time when it was cold out. After a fluid and filter change the problem gradually went away.
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