Volkswagen's gearbox keeps ringing

Yesterday afternoon, a rescue trailer arrived at the store, carrying a Volkswagen Passat. Upon inquiry with the driver, it was found that the vehicle had been towed back from the highway and suddenly encountered a problem while driving. The owner reported that there was a strange noise in the gearbox and dared not continue driving.

After being towed to the store, the Passat was still on the trailer. The driver found that even when in neutral, the car would not slide down after releasing the brake. He tried to press the clutch pedal to start the engine, and when he slowly released the clutch, he could hear a clicking sound from inside the gearbox. Fortunately, the car could still move slowly, so he drove it to the workstation.

The instrument display shows that the total mileage has exceeded 300000 kilometers and has been in use for at least 15 years.

At first, the master thought it was a problem with the ball cage inside the half shaft, but after inspection, it was confirmed that it was not, and it was likely a problem with the gearbox itself. Then, the master lifted the Passat up and let's first see what the chassis looks like.

As shown in the figure below, the front suspension is mostly made of aluminum alloy components, which were similar to Audi's chassis back then. The subframe is dedicated to the engine longitudinal platform and is now protected by a large iron guard plate, which was later installed by the owner and has two obvious oil stains.

The oil stains on the protective plate come from the gearbox, as shown in the figure below. There is a lot of sludge at the bottom of the gearbox, which is leaking out from the oil seal at the half shaft position.

The rear suspension is a torsion beam non independent suspension, and the fuel tank is designed at the rear of the suspension. Nowadays, few cars design the fuel tank at the rear of the rear suspension. If there is a rear end collision, the fuel tank is easily squeezed. There is a problem with the rear suspension now, as indicated by the arrow in the figure below, which has undergone deformation.

It can be seen that it has been significantly impacted and cracks have appeared, making it unsafe.

After inspecting the chassis, the technician continued to check for the issue of abnormal gearbox noise, as shown in the following picture. The lower guard has been removed, and it can be seen that the gearbox is basically wrapped in oil sludge. The master asked another master to start the engine and shift the gear inside the car, and confirmed that the problem was inside the gearbox, as if a damaged part had stuck in the gear.

How should this be repaired? Do we need to disassemble the gearbox for maintenance? The master said that disassembling the gearbox for maintenance is particularly uneconomical. Many of this old Passat are scrapped, so it is possible to directly find a disassembled gearbox from the dismantling factory. The price is cheap and the quality is guaranteed.

With the consent of the car owner, the master quickly found the entire transmission assembly from the dismantling factory, as shown in the picture below, along with two damaged half shafts, and even clutch pressure plates and discs. The master said that the pressure plates and discs were not used much and were obviously repaired before being scrapped.

Subsequently, the master replaced the transmission assembly, clutch pressure plate, and clutch plate, and then tested them, and the problem was solved.