Pushes old ATF out of Mercedes 722.6/722.9 and ZF 6HP/8HP units with regulated shop air, draining the converter and cooler loop a pan drop leaves behind.
If you own a Mercedes with the 722.6 five-speed or the 722.9 7G-Tronic, or a BMW with a ZF 6HP or 8HP, you already know the problem: there is no conventional dipstick, the fill point is awkward, and dropping the pan only drains part of the fluid. Owners searching for how to change 722.6 fluid properly, how to get old ATF out of the torque converter, or why a fresh fluid change did not fix a harsh shift usually end up at the same answer. Most of the old oil never left the transmission. This kit uses regulated shop air to push that trapped fluid out so the refill is mostly new ATF instead of a diluted mix.
On a 722.6 the pan holds only a share of the total fill. The rest sits in the torque converter, the cooler, the cooler lines and the valve body passages. The factory flush procedure for the 722.6 treats the converter and the oil filter as part of one service, done with the pan off, rather than as a quick plug pull. A gravity drain leaves the converter and cooler loop full of the old fluid, which then mixes straight into whatever you pour in.
The kit includes an air hose with an inline pressure gauge, an air release valve, a dedicated adapter for the Mercedes 722.6 and 722.9, separate adapters for the ZF 6HP and ZF 8HP, and two universal adapters for other fill and cooler ports. You thread the correct adapter into the fill or cooler port, feed low, regulated air through the gauge, and the air pushes trapped ATF out into a drain pan. The release valve bleeds the line down before you disconnect, so you are not breaking a pressurized fitting.
Fluid alone does not fix a worn transmission. On the 722.6, worn working-pressure regulator and overlap valve bores in the valve body are a documented cause of flared shifts, and conductor plate and speed sensor faults put the car in limp mode with stored codes. Scan the transmission first and read our 722.6 common problems and fixes guide so you know whether you are looking at a fluid service or a hard-part repair. If shift quality is the main complaint, the 722.6 E-Class shift problems guide walks through the diagnosis order. A full exchange with this kit is the right first step when the codes are clean and the fluid is simply old.
Listed fitment covers the Mercedes 722.6 and 722.9, including cars such as the SL600, SLK230 and C230, and the BMW ZF 6HP and ZF 8HP in models such as the 330i, 525i and 530i. The universal adapters extend it to other fill and cooler ports, but always thread an adapter in by hand first and confirm it seals fully before you open the air valve. The 722.6 was also used by Chrysler, Dodge and Jeep as the NAG1 (W5A580), so check your port thread against the dedicated adapter before relying on it there. Browse everything we carry for these units on the 722.6 and 722.9 parts page. If you are not sure which adapter matches your car, send us the year, model and VIN before ordering.
If the scan points at the valve body rather than the fluid, flushing will not cure it. In that case a replacement 722.6 / NAG1 valve body is the repair, and this kit is still the right way to get fresh fluid through the system afterward.
| Fits | Mercedes 722.6 / 722.9, ZF 6HP / 8HP (BMW) |
| Included | Air hose with pressure gauge, air release valve, 722.6/722.9 adapter, 6HP adapter, 8HP adapter, 2 universal adapters |
| Operation | Regulated shop air |
| Model number | KT3422 |
| Weight | 4 lb |
It includes a dedicated adapter for the Mercedes 722.6 and 722.9 fill port, plus separate adapters for the ZF 6HP and 8HP and two universal adapters. Thread the adapter in by hand and confirm a full seal before applying air. If you are unsure, send us your year, model and VIN.
A pan drop only removes the fluid in the pan. The torque converter, cooler and lines still hold old ATF that mixes into the new fill. Pushing that fluid out with low regulated air gets far more of the old oil out in one service.
Keep it low and watch the inline gauge throughout. You only need enough pressure to move fluid out of the port. Excess pressure can load the converter and cooler seals, so start low and increase gradually only if flow stops.
Mercedes specifies 236.14 fluid for the 722.6 and warns against mixing 236.14, 236.15 and 236.16 oils. The 722.9 uses the specification listed for its build, so confirm yours and never top off with a different spec.
Only if the cause is old or wrong fluid. Worn valve body bores, conductor plate faults and speed sensor failures are common 722.6 problems that fluid will not fix. Scan for codes first and read our 722.6 common problems guide before deciding.
A new filter and pan gasket, the correct ATF in enough quantity for the full system, a fill adapter for the refill side and a scan tool or thermometer so you can set the level at the specified temperature.
