The brief
The owner had been finding oil drips on the bay liner and a faint burning smell after longer drives, and a lift inspection at his usual workshop had spotted oil traces around the timing cover. He brought the 225xe in to have the leak properly dealt with.
The timing cover sits over the gears and chain that keep the engine's camshafts in step with the crankshaft, and it is sealed to the block by a gasket. When that gasket hardens with age it stops sealing along an edge, and oil weeps out: it drips onto the liner, it cooks off on a hot exhaust and smells, and over time it drops the level enough to notice at the next service.
The diagnosis
On the lift the leak was tracked to the timing cover, the gasket hardened and no longer sealing. There was no leak from the cam cover and no leak from the head gasket, and the other cover bolts were torqued correctly. Once the cover was off it was clear the cover itself had done its time, the plastic oil-soaked and rust starting at one edge.
So the job stayed contained to the front: rather than slot a new gasket onto an old cover that was already corroding, the cover itself was renewed.
The work
The accessory belt and brackets came off, the engine was supported, and the timing cover taken off. Both mating surfaces were scraped back to clean bare metal, then a new BMW-spec timing cover went on with a fresh gasket, the bolts torqued to spec in the right pattern, and the front of the engine reassembled.
The engine was run and held through a warm-up cycle, watching the join for any sign of a weep before the car went back to the owner.
The outcome
Dry timing cover, no drips on the bay liner after a road test, and no burning smell.
The 225xe went home with the front of the engine sealed the way it should be. For the owner that is the end of topping up between services and the end of that smell on the highway, and dealing with it at the gasket-and-cover stage, before the level dropped far enough to cause harm, kept this a tidy front-of-engine job.
