The brief
The A4 had been leaving oil under the car. Not a flood, but enough to leave a spot wherever it parked. The front of the engine had picked up greasy marks around the timing cover, the cabin caught a burning smell after drives, and the engine had developed a slight rough run.
Several symptoms, all pointing at the same place. Oil weeping from the timing cover gasket runs down the front of the engine. Some of it reaches hot parts and burns off, which is the smell. And some of it can track toward a spark plug well, soak into a coil boot, and upset the spark on that cylinder, which is the rough run.
One leak, four symptoms.
The diagnosis
On the lift, the leak localised cleanly to the timing cover gasket. The gasket had hardened past its sealing window, which is what happens to these over time and heat cycles, and it was no longer holding oil back at the joint. The cover itself was clean, no cracks, so it could be reused.
The rough run traced to oil that had tracked near a spark plug well and got onto a coil boot. So the job was a gasket reseal, plus cleaning the affected plug well and coil boot so the spark on that cylinder came back to normal.
The work
Removed the accessory belts and brackets, supported the engine, and took the timing cover off. Cleaned both mating surfaces, the cover and the block, back to bare metal. Any leftover hardened gasket material stops the new seal sitting flat, and you end up back here in a few months.
Fitted a new VAG-spec timing cover gasket with fresh seal rings, retorqued the bolts to spec in the correct pattern. The pattern matters on a cover this size, to pull it down evenly. Then reassembled the front of the engine.
Cleaned the affected plug well and coil boot of the oil it had picked up, so the spark on that cylinder was back to a clean connection.
The outcome
Dry timing cover. A clean bay liner after a road test, no fresh oil anywhere. No burning smell. And the engine running smoothly again with the coil boot cleaned up.
The A4 went home with the front of the engine sealed properly. For the owner, the practical wins are no more oil spots on the driveway, no smell in the cabin, and a smooth-running engine.
And a timing cover that is properly sealed will not need attention again for a long time, which on a job that involves stripping the front of the engine is worth getting right the first time.
