The brief
The 216i had a burning smell that grew stronger after long drives, fresh oil on the front of the engine, and the oil level was dropping over weeks without a visible puddle on the floor.
Three signs of an upper engine leak that is finding hot metal. Oil weeping from somewhere up high runs down the front of the engine, and along the way some of it reaches the exhaust manifold and burns off, which is the smell. Because it is being burnt rather than dripping, there is no puddle on the driveway, just a slowly dropping dipstick, the kind of leak that is easy to ignore until the burning smell makes itself obvious.
The diagnosis
We cleaned the front of the engine and ran it warm to localise the leak, because a clean front gives the new oil somewhere to show itself. The trail led to the timing cover seal: oil weeping out where the cover meets the block, with the runoff dripping onto the exhaust manifold below, which is exactly where the burning smell was coming from.
On this engine the front timing cover is a plastic piece with the crank seal built into it, so the fix is to replace the cover with a fresh seal and reseal the mating surfaces rather than trying to patch a single gasket on an ageing cover.
The work
Removed the accessory components and the auxiliary belt for access to the front of the engine, then dropped the timing cover. Cleaned all the mating surfaces, the cover and the block, back to bare metal, since any leftover gasket residue stops the new cover sealing flat.
Fitted a new BMW-spec timing cover with its seal and a matching gasket, torqued the cover bolts to spec in the correct sequence so the cover pulls down evenly. Refilled the engine oil to level, then ran the engine warm and watched the front to confirm the leak was sealed before the car went out.
The outcome
No more oil on the engine front. No burning smell after a road test. The oil level holding.
The 216i went home with the leak resolved. For the owner, that means no more smell in the cabin, no more topping up between services, and an engine that keeps its full charge of oil.
And the timing cover is a job that involves stripping the front of the engine, so getting it sealed properly the first time means it is not coming round again any time soon.