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All about Mercedes 7g-tronic gearbox (722.9)

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Schematic, guide and repair solutions.

On which cars was installed

7-speed automatic transmission of the 9-series Mercedes 722.9 from 2004 (G-tronic) is a work of art from Mercedes-Benz. It was installed on all rear-wheel drive cars. It is designed on the basis of automatic transmission of the 6th series and many parts are interchangeable.

Theoretically ideal is the 6-speed for the stepped automatic transmission. Where the gear ratios are brought together and divorced enough to comfortably jostle in urban traffic jams, and to save fuel during long delays on an unlimited route. And thus that the switching of speeds were carried out imperceptibly, but without excessive fuss, when the driver brakes before dispersal. But in 722.9 in addition to one lowering the 6th speed, one extra (7th) downshift was added for a super-economic ride through the empty and unlimited German autobahn and one extra back speed, just to be.

Traditionally, in the 9th series, Mercedes engineers laid the controlled slippage of the clutches of the torque converter, which is already connected from the first speed from the lowest speed. That is, in this machine, the torque converter cannot work as an “oil fan”, which is assisted by a clutch friction, but as a full-fledged “clutch”, which helps the “oil fan”. To do this, just press the accelerator pedal. And this feature of the 9th series results in the rapid contamination of the oil by the clutch of the bagel and the rather early need for repair of the GDT. Strongly not waiting for the cherished 150-200 tkm. This is the ideal box, which was worked on besides Mercedes designers, still programmers with Siemens electronics, has typical “electrical” problems. Until now, this box suffers from a child’s electrical illness — the failure of the electronic board.

The whole family 722.9 likes regular replacement of (correct) oil and maintaining its level is not below the norm. For AKP before there were four types of oil filter and crankcase.
Now install two different oil filters and crankcase. The oil level here is very important, therefore the design allows it to be easily maintained and checked. If the oil does not pour out of the control plug during testing (t ° = 45º, Drive, engine wound), ATF should be refilled.

At the moment, there are two different types of oil for the gearbox: ATF 134 (red, tolerance 236.14) to the serial number of gearbox 2834526 and FE-ATF 134 (blue 236.15) with the serial number of gearbox 2834527. Frequent oil changes markedly prolong the service life of the box. If the hedgehogs of metal began to appear when inspecting the pallet magnets, then it’s time to go to the bulkhead of the box to extend her life for several more years. For bulkheads, the services are still preferred by reliable and expensive original overlays. Familiar with this box of the master order quite quality repair kits of gaskets and seals “not the original” — Transtek or ATOK. Frictions on Mercedes fashion — one-sided, are replaced most often by frictions of package K2. They are followed by K1 clutches, but with burned oil it is advisable to change the complete set of friction discs. To all the above sets for a typical overhaul of an overheated box, almost always order another set of pistons.

The first child disease of the 9th series already repeats the old history with third-party suppliers — the failure of the electronic connector board — the Y3 / 8n1 speed sensor (the turbine speed sensor — VGS) burns out. Separately, the board (in the right way) cannot be executed on blocks: A2202701006 A2202701106 A2202701206 A2202701406 And AMG cars with wet clutch. Another “childhood illness” of the 9th series — breaks the bell of the case.

In the bulkhead, the clutch packages K1 and K2 are checked first. It is there that one-sided clutches are burned. K1 — internal teeth — single-sided friction with external tooth and K2 , — with the outer tooth and — clutches with an internal tooth , The hydroplate works here at temperatures up to 130º and is very capricious to overheated and dirty oil, chips, small springs can break down, solenoids can clog. Masters claim that it is because of the abnormal operation that the hydroplates do not receive the required oil pressure properly, the clusters are burning, and all other problems are happening along the chain.

Since the designers provided repair of the hydraulic unit without dismantling the automatic transmission, this problem, noticed on time, is solved with relatively little blood.

If the summer heat your horse suddenly refuses you — it’s time to go to the diagnosis and order a gasket pallet, oil with a filter. Oil is used here for two generations, differing: red to 2010 and blue after. The problem of capricious electronics has very much spoiled the image of Mercedes as a reliable manufacturer. Replacement of the motherboard and hydroblock of the first issues of 722.9 became an epidemic, as in some models the replacement of one card often led to a rapid repetition of this problem. Mercedes accuses Siemens of everything. Siemens argues that the fault is due to the insufficient cooling of ATF oil or the driver’s leg, which loads the accelerator’s iron too heavily. The designer even provided for switching off the clutch slip of the transformer lock if the oil temperature rises above 140 °. Keep in mind, in this mode the car accelerates not so actively, but still rides.

And this temperature is also destructive for the machine as a human body temperature of 40 ° C. You can still live, but no longer work. Automatic transmission control unit (Multi-function switch / Servo module), Control module, ISM / MLPS the problems are found in the Multifunction switch (Servo module), Control module, ISM / MLPS. And although the iron of this automatic is very reliable, but because of malfunctioning electronics, the problems of the oil pump lead to a chain of problems with the rear planetary series, with bushings. Many owners manage to prevent them, putting the car on time in the repair of automatic transmission.

Owners of this modern and very comfortable automatic transmission should take it as a rule not to overheat the automatic transmission and in every visit to the car maintenance check the automatic transmission oil for color, the presence of dirt and shavings in the pallet. Yes, and change the oil with a filter every 60 tkm. Once every two years, such costs for maintenance of automatic transmission — a small fee for the confidence in his horse. (From) PS The article is slightly superficial, but for a general understanding of the 7G Tronic boxes, that’s the thing.

For reset, adaptation and personalization of 7G-tronic gearboxes possible using:
1. Abrites AVDI + MN026 software license
2. Mecedes Exterme
3. SimpleDiag

Regards,
Carscanners Team

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