I've posted on here about my tranny troubles and took it to a shop and wondering if what they said sounds reasonable. To make a long story short, my transmission does not want to shift into 4th unless I quickly move the lever from D to N back to D or if I am on the hwy and I go to 3000 rpm, then it will drop into 4th. So the shop and I unhooked the throttle pressure cable slide and then drove it manually shifting it. Still same story with 4th gear. So they concluded is must be in the transmission not something on the outside like the throttle pressure governer or whatnot. They said that there is a stuck or hanging valve in the valve body causing this. They want to pull the valve body and find and fix the offending valve. They said it would run me around 250 give or take a little. Sound right?

Note: Already tried the kickdown switch, I unhooked it both at the gas pedal and at the transmission....no difference.

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'86 420SE Euro
904 Midnight Blue, Gray Velour
Dad bought it new, now I own it.

"A Mercedes-Benz is like a fine wine, it only gets better with age."

If the transmission can hold 4th gear, with no slippage, you have a control problem. Valve body. Valves don’t stick on there own, Metal in the fluid from Normal wear of the transmission components or abnormal wear is the likely cause. Ask that you be inform of the oil pan condition, if there is heavy metal contamination you will need a rebuild. If the pan is clean have the transmission serviced. I prefer flushing.

I just changed the fluid and filter not even 2000 miles ago. Nothing much in the pan. Only very very faint flakes, but I had to hold it in the light and tilt it side to side in order to see them. No piles or anything of that nature.

How can it be a control problem if it still won't shift into 4th with the throttle pressure cable unhooked?

Here is more info: When in 4th, and I hit the gas and it downshifts or I manually downshift it into 3rd with the lever, it pops right back into 4th. But...if I am in 4th and slow down and it alone downshifts into 3rd, it won't go back into 4th when I speed back up unless I do the lever move again.

I really want to find the root of this problem because it is driving me nuts!

Would to recommend one of these t-tec type power flush with detergent deals??

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'86 420SE Euro
904 Midnight Blue, Gray Velour
Dad bought it new, now I own it.

"A Mercedes-Benz is like a fine wine, it only gets better with age."

Can anyone tell me this: In order to totally narrow it down, what are all the components on the control side of a transmission?

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'86 420SE Euro
904 Midnight Blue, Gray Velour
Dad bought it new, now I own it.

"A Mercedes-Benz is like a fine wine, it only gets better with age."

The Bowden cable does not control or command a shift, it controls shift timing, and so with the cable disconnected all shift would be stacked, early. If you are cursing on the highway in 4th gear for miles, and the car stays in 4th, does not drop out. A possibly is a valve body control problem. What command 4th is?

Valve body

[3-4 shirt TV valve
3-4 shift valve
3-4 sequence valve
3-4 feed control valve
Rear clutch sequences valve.

If the Trans drops 4th gear when hot or cold

Kick down solenoid
Low governor oil
Leaks in the K2 or K2 drum
Burnt clutches.


The number one step in diagnosing any transmission drivability problem is to check, oil level and condition, oil pressures ; working, modulator and governor. A flush is about $195.00, it is more cost effective to have the valve body rebuilt for $250, get a guarantee first. That is easy for me too say it is not my money.

C32 AMG replied: "f you are cursing on the highway in 4th gear for miles..."

Sounds like me in L.A. traffic

WHATEVER C32AMG says about transmissions, I LISTEN carefully and do it !!

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The Golden Rule

1984 300SD (bought new, sold it in 1988, bought it back 13 yrs. later)

Sorry for the late response, but I am not able to get on the internet nearly as often as I used to. Here is my biggest problem. What transmission shop do I take it to? I took it to a "Import Specialist" that works on many MBs and other european cars, but the impression that I got is that they were wanting to throw parts at it, not actually diagnose it. They wanted to put a new valve body on it w/o ever putting any gauges on it or anything. I am not very confident with them. I am not ready to drop that kind of money w/o being 99% certain that it will fix it. This shop wanted $600 to R&R the valve body and send it off to get it rebuilt. Where can you send it for $250? How hard to R&R a valve body?

One more symptom: When on the hwy in 4th and want to downshift to 3rd to pass, it is a very hard jerky downshift, but then if you do it again right after, it's smooth.

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'86 420SE Euro
904 Midnight Blue, Gray Velour
Dad bought it new, now I own it.

"A Mercedes-Benz is like a fine wine, it only gets better with age."

The valve body is easy to remove and install. You will find what you are looking for in this thread



Does Anyone Know How Automatic Transmissions Actually Work?