The brief
The Golf was vibrating heavily through the cabin, the owner could see the engine move whenever a gear shift went through, hard acceleration triggered a bang from the engine bay, and the general engine noise inside the car had grown. Four complaints, all pointing at one thing: the mounts that hold the engine and gearbox to the body have given up.
The drivetrain doesn't bolt straight to the car, it sits on rubber mounts that let it move a controlled amount and stop its vibration reaching the cabin. The main engine mount on this car is a hydraulic one, with fluid inside to damp it. When that mount tears and the fluid leaks out, and the transmission mount and the lower torque link wear with it, the engine moves around too much, slamming metal on metal under load, and every vibration comes straight through. That's the bang and the noise and the shake.
The diagnosis
The inspection found it: the front engine mount was torn with its hydraulic fluid leaked out, the transmission mount was deflecting well past spec, and the lower torque link, the dogbone that stops the engine rocking fore and aft, had a worn bush. The bang under acceleration matched the rubber-to-metal contact when the slack ran out.
With all three worn, the right call is a full set, not one side. Replacing one fresh mount against two tired ones would just leave the drivetrain isolated unevenly and bring the car back for the rest in short order.
The work
The engine and gearbox were supported, the failed front engine mount, the transmission mount and the lower torque link all came off, and new VAG-spec parts went on, torqued to spec in the correct order so the drivetrain sits where it should.
Then the engine was run at idle and through a hard throttle test to confirm the bang was gone and the engine stayed settled in the bay.
A road test confirmed the cabin was quiet and smooth again.
The outcome
Smooth idle, the engine settled in the bay on gear shifts, no banging under acceleration, and the cabin noise back to normal.
The Golf went home with the drivetrain properly isolated again. Doing the full set, all three mounts together, means it's a job that's finished, not one that'll need a second visit for the mount that was left, and the bang, which is the sound of metal hitting metal, is gone for good.
