HVAC Burning Smell

[3Series]

Does anyone know the symptoms of a failed valve cover gasket?

When I'm driving the car I sometimes get a burning smell coming from the HVAC when it's blowing hot air. The HVAC is on auto recirc. When I manually change to cabin re circulation, the smell goes away. The same thing happens when I turn the hvac off.

I checked under the hood once to try to smell something after I parked in the garage but didn't notice anything. BTW, it's been single digits weather around me for weeks.

[slowlanemcvane]

Failed Valve Cover Gasket Symptoms:

1) Oil loss, oftentimes without any pooling/puddling/dripping onto your garage floor.
2) Occasional burning smell, as oil will sometimes drip or run onto exhaust header/header flange/catalytic converter.
3) Sometimes you will see smoke underhood or coming out from the cowl vent.

From my experience with most engines on cars that I have owned, the valve cover gaskets usually tend to fail on the exhaust side of the engine (passenger's side), and I think this is largely due to the large temperature swings that happen on that side, as the exhaust heats the cylinder head, then cools again after the engine is shut off. It makes the gasket brittle, then it fails slowly.

[bawareca]

Originally Posted by slowlanemcvane

From my experience with most engines on cars that I have owned, the valve cover gaskets usually tend to fail on the exhaust side of the engine (passenger's side), and I think this is largely due to the large temperature swings that happen on that side, as the exhaust heats the cylinder head, then cools again after the engine is shut off. It makes the gasket brittle, then it fails slowly.

Also,in BMW case,the exhaust side accidentally happens to be the lower side of the head,where the oil collects