Burning Smell on 2003 BMW 530i

I had the value cover gaskets replaced and smell went away for a short while (several weeks), but is back again. Took car to shop for a oil leaks visible, oil level fine. Will be taking car in for more diagnostics, but was wondering if it could be a coolant hose leak. Smell is prevalent when the heater blower is on and after driving for awhile, not when you first start the car.

Asked by for the 2003 BMW 530i
Coolant odor in a BMW is not very noticeable- the coolant BMW uses does not have much odor. You would also have a low coolant warning light on by now. When a valve cover gasket is replaced on a 530i oil will leak onto the exhaust manifold- it is possible the shop that did the work did not clean it up well or may have not installed it properly. Let me know if you need more help! Greg
it is very common to also have a secondary oil leak; usually at the oil filter housing gasket. because oil always flows downhill, it's always good to start at the
top (valve covers). it's not your car; it's just every
six cylinder BMW ever built---they all leak.