M54 burning oil at idle

[Skrappy503]

i recently purchased an E46 325it, after some research i had fount he the reason for burning oil is most likely the CCV system. i have replaced the CCV system with factory BMW parts, also the valve cover gasket and the oil pan gasket. I have checked all of my vacuum lines and i can not figure out if it is a vacuum leak or just bad rings. i assume that i it was bad rings than i would burn oil a higher RPMs as well as at idle. not sure where else to look. maybe dipstick o-ring.
It seemd thebe worse when i slow to a stop on a down hill.

[MarcoZandrini]

The M54B25 engine (this is BMW’s designation) isn’t known to burn oil. The 3 liter version (M54B30) dies burn oil. Your last sentence seems to be the key, if I read it correctly. That is, the engine burns oil when you’re engine braking as the car goes down hill. That’s a good indication that the valve seals are shot. They can be replaced without removing the head. If you decide to replace the seals ensure you buy seals made by the supplier to BMW.

Now, if I misinterpreted the last sentence then the cause could be the piston rings. Go to E46Fanatics and search for GM Top End Cleaner soak. Basically, you remove the spark plugs and pour a couple of once of the GM fluid into each cylinder and allow it to soak for 24 hours.

[Skrappy503]

I guess the next task would be to do a leakdown test and see where it's leaking.

[328 Power 04]

I think he meant valve stem seals.

[dhurley34]

What makes you believe its just burning oil at idle?

[Skrappy503]

because i only get smoke at start up and when i slow to a stop. i believe it builds up in the exhaust and i get a cocentrated cloud when i then take off. like i said it is the worst on down hill stops and on uphill it seems to be a little less so.

[Raddee]

+1 on the valve stem seals.