Hi all, I need some advice about an engine failure in a Z4, the car is 7 years old, has done less than 20K and is used almost exclusively on short runs of less than 5 miles. It was last driven hard in October for just a few miles and has more or less pootled around gently since then.
The car has a FSH and last had an oil change (using Mobil 1) about 6 - 8 months ago, it hasn't been topped up since as it hasn't needed it.
During the very cold spell the car was started and left idling whilst the screens were scraped etc. during this idling the car began misfiring and the cabin filled with smoke. The car cut out and would then not turn at all, seized solid.
On removal of the head it appears that up to 3 cylinders had completely filled with engine oil. The dealership have literally stripped the engine down to it's component parts and say they can identify no problem and are completely confused as to how the cylinders could have filled with oil. They have stated that the engine appears immaculate inside and more or less as new.
As it stands at the moment the bill is over £2K to strip and rebuild the engine and there is no guarantee that the problem won't reoccur immediately. The best idea I could suggest is that the oil breather system has somehow become clogged, perhaps with something having frozen, and this has subsequently thawed out leaving no trace of the problem, but how would this fill a cylinder?
Theories please!!??
Edited by Blue {P} on 26/01/2010 at 11:24
|
|
If some cylinders were filled with oil it infers the oil entered after the engine stopped or the engine stopped when the first effected cylinder hit the compression stroke. Did the garage inspect the inlet manifold for oil contamination as I suspect that is where the oil came from and was ingested into the engine thus the missinf then sudden stop. With all the short runs it could be mayonnaise in the breather system that froze and the engine overpressurised. Are you sure the oil level was correct after the oil change, I assume so as it has run OK for 6 months since then. Regards Peter
|
|
|
It is almost certainly the cyclone oil seperator under the intake manifold, a well know problem in humid and cool climates (like the UK) and a regular source of winter repair work for dealers. Ideally these should be changed at 50k or 5 years to stop this kind of problem.
They need to fit a new cyclone unit plus clean/replace the hoses that go to it. It was the freezing weather that probably caused the gunk inside to set hard.
|
|
By the way, was it a BMW dealer that looked at this car? If so then should be aware of this problem, its not that rare. There is no need to completely strip the engine, although the inlet manifold does have to be removed to clean it and fit new cyclone unit. Oil can be spun out of the cylinders. If they are completely stripping the engine than thats a lot of unecssary labour you are paying for, £££ !!
|
Thanks for the comments guys, I shall pass them onto the owner of the car, it sounds as though I may have been vaguely correct with my theory!
|
Just a brief update, the owner is very grateful for the comments here and is putting them to the BMW service manager tomorrow when he returns to work to see if this could be the cause.
|
|
|
|
