Symptom: a Passat B4 automatic car in the process of moving, hanging in the D block, as long as the speed of 70 km or so, there will be clutch slip phenomenon, the engine speed rose sharply, the speed down.
     Troubleshooting: VAG1552 can be used to determine the three gears when the work began to slip. VAG1552 query found no fault storage, then suspected to cause a mechanical failure slip. Open the gearbox and found the third gear clutch has a slight ablation phenomenon, so replace the clutch plate, but the test is still the fault. And suspected that the oil is not enough to cause the clutch slip, but after the replacement ATF pump still no better.
     Finally, through careful examination found that the surface of the valve body has a small hole with the adjacent oil channel connected, so the valve body is suspected to have failed, after the replacement really disappeared, after repeated search and asked the experts to confirm that the Passat B4 Automatic car seat change box into the channel due to trachoma caused by oil pressure can not be established, there has been a slip phenomenon.