Valve Body Repair 722.6 722.9 Mercedes SsangYong

7G-Tronic (722.9)  is a seven-speed automatic transmission developed by Mercedes-Benz. For the first time, this fifth-generation automatic transmission was shown in the fall of 2003 on models with 8-cylinder engines and became the first seven-speed automatic transmission that was installed on serial passenger transport. It was originally installed on 5 8-cylinder models: E500, S430, S500, CL500, SL500, was also available on some 6-cylinder engines including 320 CDIs, new at that time. By the way, 722.9 was initially unable to work in tandem with 12 cylinder engines, as it had a torque limit; on the S600 and S65 AMG models, they continued to install 5G-Tronic.

The company stated that the 7G-Tronic would save up to 0.6 liters of fuel per 100 km (depending on model) and accelerate faster, since 2 additional gears increased the range of gear ratios, which allowed to reduce the differential speed when shifting gears, and this positively affected the engine .

Structurally, 722.9 is the evolution of the popular 722.6 (5G-Tronic) box, which means it inherited both strengths and weaknesses - one of them is the valve body. Every car owner with automatic transmission inevitably faces the fact that when a serious mileage of 100-150 thousand kilometers is reached, the box does not behave as perfectly as before. There are shocks, bumps ,,slips when shifting gears,. Often the problem is in the valve body, which is responsible for shifting gears. In this article, we will tell how the masters of the Maktrans company repair valve bodies 722.9 and how much it costs.

Let us consider pricing, it is not fixed and the repair price consists of the cost of the work performed and the used parts. In the case of 722.9, it is better to contact the service earlier (if the first symptoms appear), because if you continue to operate the car with a faulty valve body, it can lead to the box overhaul - which will include replacement of solenoids, repair of the control board, and replacement of mechanical parts of the box - drums, pump and so on.

                                                                                                 The  calculation of the repair cost that we will show in this article:

Repair beginning - disassembly and initial diagnostics

We got a valve body removed from a Mercedes W221 V6 3.5L for repair. In this case, the valve body repair is part of the overhaul, the customer’s K1 piston has collapsed and finely dispersed metal chips have clogged the hydraulic part of the box.

                                                                                                    We begin to disassemble. We unscrew the electronic board and put it aside.

In the last photo we see metal dust on the magnet of the manual valve which is responsible for shifting gears. We remove and clear of chips.

Repair of control electronic board 722.9

Before disassembling further, we will dwell on the electronic control board. The electrical part of the 7G-Tronic was developed by Siemens, the main feature is the placement of the control board directly inside the automatic transmission case, theoretically this should ensure the cooling of the board and its stable operation, however, electronics became one of the main problems of the 9 series boxes, speed sensors often fail - at the same time, the following features of the car’s behavior are observed: in Drive mode at a steady gear (usually fifth or higher), a drop in torque occurs, the car stops, the box goes into emergency mode. After turning the ignition off / on, the emergency mode may disappear, but over time the situation will repeat more often - until the speed sensors completely fail. In this case, in addition to emergency mode, one forward and one reverse gears are available.

A diagnostic tool is used to determine the cause of the malfunction. At the end of the diagnosis, the following errors are possible:

• P0717 Signal from structural unit Y3 / 8n1 (turbine speed sensor (VGS) is not available)
• P0718 Faulty structural unit Y3 / 8n1 (turbine speed sensor (VGS)
• P2767 Signal from structural unit Y3 / 8n2 (internal speed sensor (VGS) not available)
• P2768 Faulty structural unit Y3 / 8n2 (internal speed sensor (VGS)

There are two solutions to the problem - replacing the control unit or replacing speed sensors. Maktrans company offers the second option, as the most beneficial for the car owner, but if necessary, the control unit can be completely replaced.

The work on the replacement of speed sensors consists of the following steps:

1. Fixing the board on a special mounting plate
2. Disabling Loops
3. Removing failed sensors
4. Replacing sensors with new ones
5. Connection of loops

Following sensors are also available:

Speed ​​sensor kit (Y3 / 8n1 Turbine rpm sensor and Y3 / 8n2 Internal rpm sensor) automatic transmission 722.9 04-up

                                                                                             This is the procedure for replacing 722.9 speed sensors

After connecting the speed sensors, the electronic control board is connected to the valve body and installed in the automatic transmission. The next operation is to check the car on the go with the connected diagnostic equipment. The absence of errors indicates the correct repair of the electronic control unit. Replacement of speed sensors is the most profitable and quickest solution to the problem offered by the specialists of the Maktrans company, since it does not require the purchase and reprogramming of the electronic control unit. Sensor replacement price - $ 250

                                                                                                                             We continue to disassemble

Valve body insides

We extract accumulators and balls. In the block there are 14 steel balls and 2 plastic balls, we recommend photographing the plate before disassembling.
 

Plates are placed in the washing machine.

Washed plates are blown with compressed air and we proceed to the vacuum diagnostics.

We check the plungers for jamming, must move freely in the channels and not get stuck

There is a problem with the main pressure valve, the output in the channel is large and poorly vacuumizeded. The solution is to install a repair valve. Maktrans produces repair plungers for all popular automatic transmission models, the range for 722.9 can be viewed at the links below:

• Oversized Valves 722.9
• Reamer 722.9

                                                                              We fix the plate on a special machine and drill a hole in the size of the repair plunger

We take  main pressure oversized valve produced by Maktrans company 

We insert the valve and test. Tightness restored.

Solenoid check and repair

In the  722.9 valve body - there are8 solenoids, it is possible to determine the type of the solenoid by the color of the cap. Solenoids with caps of the same color - interchangeable:

EPC (with black cap)
TCC (with blue cap)
K1 (with blue cap)
K2 (with black cap)
K3 (with black cap)
B1 (with black cap)
B2 (with blue cap)
B3 (with blue cap)

                                                          We install the solenoid in the stand and test. All solenoids showed a stepped graph due to contamination.

Flush the solenoids, change the rubber seals and test again

The problem with the solenoids is solved, it can be installed back into the control board. If the output inside the solenoid is too large and after washing, the graph still indicates the incorrect operation of the solenoid - we replace it with new ones.

Assembly

We begin to collect. We install the batteries and put the balls. It is very important to place all the elements as they were originally located, one mistake - and you will need to remove and disassemble the valve body again, the car will not go as it should.

We install a pre-washed separator plate and tighten observing the necessary tightening torques of the bolts.

Control board installing

The valve body is assembled and ready to go to the client.

Maintenance tips 722.9

• The first, and perhaps most important, is an oil change that is timely and more frequent than Mercedes itself advises. You should not wait for 150-200 thousand kilometers, as a rule, at this stage the box will “die” completely and will require major repairs. When visiting the service station, you should check the purity of the transmission fluid and, if necessary, replace the filter and oil, ideally change after every 60,000 km.
• It is necessary to avoid overheating of the box. The electronic circuit board crashes due to dirty hot oil. We recommend installing additional cooling.
• A mandatory part of the overhaul should be the repair of the torque converter.​