1999 W210. Transmission will not shift up after engine revs up to redline

[wclrk]

Hi! I hope you may be able to provide me with some insight before I take my car to a mechanic. I own a 1999 V6 E240 (W210) MB, fitted with an M 112.911 engine and a ZF 722.6 five-speed automatic transmission. The car has 189.000Km (±117,000miles) and has been exceptionally well cared for.



Some months ago, I began to notice that on the very rare occasions when I floor the gas (kickdown switch), the transmission downshifts and the engine revs to redline, but the transmission does not upshift when the redline is reached. If I let go a little off the gas pedal, it then upshifts.

When driving normally -not aggressively-, the transmission downshifts and upshifts completely normally. It also responds normally to manual shifting. The car has not gone into limp mode and the it has not flashed a “check engine” warning.



I have the feeling that this might be some kind of an electrical issue, but I am not at all sure.



Although in an excellent condition, the car is old, and I would be reluctant to spend more than its resale value in fixing an expensive transmission issue. Thanks for your advice.

 

[LostKiwi]

First things first the 722.6 gearbox is not a ZF unit. It's Mercedes own unit that's also fitted to Dodge, Chrysler, Ssangyong, Jaguar and Porsche vehicles.

When did the gearbox last have a transmission flush and filter change?

 

[Frontstep]

Good point can't beat clean.

 

[mioba]

Perfectly fits in the window "sealed from service sheet".

 

[wclrk]

First things first the 722.6 gearbox is not a ZF unit. It's Mercedes own unit that's also fitted to Dodge, Chrysler, Ssangyong, Jaguar and Porsche vehicles.

When did the gearbox last have a transmission flush and filter change?

At 65.000 Km.

 

[Steve@Avantgarde]

I'd say that was comepletely normal for these old boxes. Werent the smoothest or raciest of transmissions.

 

[5w155t0ny]

At 65.000 Km.

that could be your issue then. Get that 'box a new filter and oil. It'll thank you for it.

 

[LostKiwi]

189k -65k is 124k Kms.
It's due another filter and oil change.

 

[mioba]

189k -65k is 124k Kms.
It's long overdue another filter and oil change.

Corrected

 

[Doug1234]

“the redline is reached. If I let go a little off the gas pedal, it then upshifts”
Similar with my 97 w210 e300td I owned, it would does this on 3rd to 4th gear change and it would stay in 3rd at anything over about 3k revs until I backed throttle off a bit.
Rough 2-1 at crawling pace in traffic and sometimes thumped into gears .. rare occasions shifter lever had no effect ie would not go into any gear at all.
Would stay stuck in 3rd or 4 until engine restarted .. new conductor plate cured mine.
Mine also had no warning lights or any codes showing even after it finally hsd enough and went full limp leaving 2nd and reverse gear only. New plate and oil and filter and one abs code cleared and was all ok

 

[pgh13]

Also, while changing the filter, check the electrical connector; the O rings on the bushing can leak leading to problems with the TCU if fluid from the leaking bush wicks up the loom

 

[wclrk]

Thank you for your advice. I had not performed further transmission oil changes because the MB dealer told me it was unnecessary and possibly detrimental, as these transmissions wer4e "sealed for life". The 65.000 Km oil change was perfomed at the suggestion of an independent mechanic. I believe regular oil and filter changes are now the accepted procedure for these transmissions. I will go and change fluid and filter.

 

[LostKiwi]

Thank you for your advice. I had not performed further transmission oil changes because the MB dealer told me it was unnecessary and possibly detrimental, as these transmissions wer4e "sealed for life". The 65.000 Km oil change was perfomed at the suggestion of an independent mechanic. I believe regular oil and filter changes are now the accepted procedure for these transmissions. I will go and change fluid and filter.

Sealed for life just means sealed till it dies.

 

[5w155t0ny]

Thank you for your advice. I had not performed further transmission oil changes because the MB dealer told me it was unnecessary and possibly detrimental, as these transmissions wer4e "sealed for life". The 65.000 Km oil change was perfomed at the suggestion of an independent mechanic. I believe regular oil and filter changes are now the accepted procedure for these transmissions. I will go and change fluid and filter.

The only thing it would be detrimental for would be the dealer’s balance sheets as they would be losing out on a repair or replacement gearbox job.
It is never a bad thing to ensure your gearbox runs nice clean oil.
What a ridiculous statement for a supposed professional enterprise to make.

 

[charlysays]

These old 722.6, despite having a weak bushing on the k2 clutch and possibly some weakness in the conductor plate will outlive the rest of the car (but perhaps not the engine) with regular servicing.
Change the fluid every 30k miles and filter every 60k miles if you want the least chance of problems. Or change both if you're flush.
Changing the fluid this regularly prevents conductor plate problems too as there's less metallic debris getting stuck all round the speed sensors and layering up on the conductor plate.
Usually the O rings on the electrical plug also need changing but should last atleast 10-15 yrs before they start leaking again.
It's really not a difficult DIY job and the fluid doesn't need to be anything special although if you're not confident it might be worth getting a friendly forum member to help you the first time.
I recently bought 20L of Fanfaro universal ATF which exceeds the minimum spec for the the NAG1 (early 722.6) for about £50 with free postage on ebay, that will do almost three full fluid changes.
I have found a bottle of lucas transmission fix works wonders too. It's gloopy though so best to mix it with several litres of ATF before attempting to pour it down the dipstick tube. It will reduce temperatures in the clutch packs and moving parts and improve shifting. It actually kept a faulty 722.6 I had trucking for another 40k miles once. I began losing gears from the top down, no fault codes. One bottle kept it running perfectly for 20k miles, then another bottle and a fluid change kept it going another 20k miles at which point i crashed the car lol.

 

[Doug1234]

One funnel with some pipe attached to it in the gearbox dipstick tube, another small bit of pipe down beside this … this lets air out so you can fill it quicker.
One bucket of very hot water..one can of gearbox oil sitting in the bucket getting warm…change water after about ten minutes and leave it for another ten and then you will find you can get about 4.5 litres into gearbox in around two minutes instead of the usual hour faffing around when the oil is stiff and cold.

 

[wclrk]

Okay guys. I have changed the ATF and the filter. The electrical plug was changed, too. Sadly, nothing has changed. What would be the next step?

 

[5w155t0ny]

Okay guys. I have changed the ATF and the filter. The electrical plug was changed, too. Sadly, nothing has changed. What would be the next step?

Have you reset the transmission to clear the shift patterns?

 

[00slk]

As above, I had the same issues with my old s211 and had to have the transmission reset on Star.

 

[mioba]

Thank you for your advice. I had not performed further transmission oil changes because the MB dealer told me it was unnecessary and possibly detrimental, as these transmissions wer4e "sealed for life". The 65.000 Km oil change was perfomed at the suggestion of an independent mechanic. I believe regular oil and filter changes are now the accepted procedure for these transmissions. I will go and change fluid and filter.

These boxes are sealed from the service schedule,
They have filters and plugs and the same service items, serviced the same way as many boxes.
My W220 box is the same breed (vin cutoff date) means its apparently a non service box, yet later vin cars with identical box are a service item.
Change the oil every 35k miles, period.