W124 722.344 Transmission wont upshift when warm - PeachParts Mercedes-Benz Forum

HansAA · #1 10-27-2011, 11:36 AM

My auto transmission only shifts up from 2 gear when its cold. If I floor it when warm it wont shift beyound first gear. The kickdown is disconnected. I just had the valve body replaced and changed the K1 and K2. The atf fluid and filter are new. Dexron III. Atf level is more or less on the max level with hot transmission. It could have been a hunch less oil in it. It does not respond to any bowden cable adjustments. Cable is not broken.

My mechanic advised me to hit the transmission from behind with a hammer or so. To get stuck or hanging parts moving again. Does this make sense? Could it be a stuck valve or so?

ps2cho · #2 10-27-2011, 12:22 PM

I doubt hitting it with anything is going to make a difference.

Was your "mechanic" the one who both uses hammers and replaces valve body's by any chance?

JohnM. · #3 10-27-2011, 03:46 PM

Valve body swaps are always risky and almost never cure the problem. I'd start looking for a new (used) transmission.

d.delano · #4 10-27-2011, 08:11 PM

From Mitchell Repair Information Company-

Will Not Upshift

Incorrect governor pressure. Defective governor assembly.
Check kickdown solenoid valve for a tendency to stick or for constant
voltage to solenoid caused by a defective fuel pump relay or sticking
kickdown switch. Valve body dirty or valves sticking. Repair or replace valve body.

benzme · #5 10-27-2011, 09:13 PM

Would a bad vacuum actuator have anything to do with it?

ps2cho · #6 10-28-2011, 01:29 AM

Quote:

Originally Posted by benzme

Would a bad vacuum actuator have anything to do with it?

If its disconnected, possibly. Just check the vacuum line is still attached.

HansAA · #7 10-28-2011, 08:52 AM

Since my "mechanic" only deals with MB, he is no rookie on the brand. The tranny had the atf fluid flushed twice after the valve body was replaced. I just had it replaced a third time, and it still does not look good. I'm bringing the car back to him on monday, since I dont know where to hit it myself. The same day I'll hopefully pick up a -88 transmission with the TC on it.

Most probably I'm ending up opening up the transmissions and swap parts...

Kickdown solenoid checked and OK.

compress ignite · #8 10-29-2011, 03:14 AM

New Transmission Mechanic (Or at least a Second Opinion.)

Oh,and on this (The Less Sophisticated side of the North Atlantic) shore,we
Don't "Flush" transmissions
[TOO,TOO,MUCH Empirical Proof of Transmission DAMAGE]
BUT "Drain and Fill" the Transmission and Torque Converter.
Along with installing a New Transmission Filter.

[HINT: As destructive as "Power Flushing" an AutoBox is... AFTER TWO almost
consecutive Flushes the Fluid should be as Pure as if it NEVER left the Sealed
Container it came in.(I seriously DOUBT you've gotten TWO fresh fluid changes!)
]

The only SAFE thing (For YOUR Mercedes) to allow the "Mechanic" to "HIT" with a Hammer is HIS HEAD!

Stretch · #9 10-29-2011, 04:45 AM

If you end up trying to make one good transmission from two transmissions you'll still need a sealing kit. They are not cheap - and irritatingly they give you enough to do the whole series of transmissions so you end up buying way more than you need. If you can get someone to sell you individual parts then please tell me where you got them! Here in Holland they wouldn't do that - they can only be bothered with the "big sale"...

My guess with the hammer incident is that the mechanic is thinking that the governor is stuck or sticking and perhaps thinks that whacking it with a hammer is the way forward. I advocate removal and cleaning... but hey whatever if you trust the guy that's your business. At least you've psyched yourself up to buy a second transmission so that expense won't come as a shock if it turns out to be necessary.