The brief
The owner had been finding fresh oil drips on the bay liner of the Passat and smelling burnt oil after longer drives. Tracing the leak with a torch led him to the front of the engine and the timing pulley cover. He brought it in.
The timing pulley cover seals the front of the engine where the chain and sprockets run, and on this engine it's a plastic cover with the seal built into it. The plastic ages, the seal hardens, and oil starts weeping out, which is the drips on the ground and the burnt-oil smell when it lands on something hot after a run. Caught early it's a tidy job; left to spread, oil can track into the plug wells and start costing coils.
The diagnosis
On the lift the leak was localised cleanly to the timing pulley cover. The plastic and the seal had aged past the point of sealing, so it was weeping oil down the front of the engine, while the other gaskets in the area were dry.
So this was a timing cover replacement, the whole plastic cover with fresh seals, rather than trying to coax a tired plastic part into sealing again.
The work
The accessory belts came off, the engine was supported, and the old timing pulley cover removed. Both mating surfaces were cleaned back to bare metal, a new VAG-spec timing cover went on with fresh seals, and the bolts torqued to spec in the proper pattern before the accessory drive was reinstalled.
A road test followed to confirm it was sealed.
The outcome
Dry timing cover, no drips on the bay liner, and no burnt-oil smell after the road test.
The Passat went home with the front of the engine sealed properly. An oil leak at the timing cover only spreads, and once it's into the plug wells it gets expensive, so sorting the cover when it did kept the job to the cover and a clean-up.