Oil consumption back to normal after replacing oil seperators - The Unofficial BMW M5 Messageboard (m5board.com)

maxm5 · 8th August 2007, 14:29

My beast generally uses about one litre of oil per 1000 miles up until about three months ago when it started using about one litre per 300 miles.

I thought I'd try replacing the oil seperators before doing any major work on the engine and the results were instant.

Here's the diagram showing the parts..

http://www.realoem.com/bmw/showparts...53&hg=11&fg=15

It took me about 30 minutes to replace them but I should warn you that it will take alot longer if you have big hands! I still ended up with a few missing knuckles when I had finished.

All I had to remove was the air intake hoses attatched to the MAFs and intake manifold. If you have big hands I think you'd need to remove the top engine cover first.

I actually replaced the seperators about 6 weeks ago but wanted to get 1,500 or so miles on the car before posting my experience.

The parts cost about £48 ($96), which I have almost saved in oil costs in the last few weeks!

The old ones looked a bit clogged up with gunk which you'd expect after 100k+ miles. I think the oil seperators condense oil vapour which then goes back into the cylinder head rather than being burnt in the exhaust - I'm guessing the clogging of my ones causes all of the oil to get burnt in the exhaust rather than being put back into the engine.

FYI - My beast now has 111k on the clock and I use Mobil 1 which does get used up about 20% quicker than TWS. Oh yeah and I do not baby my car!

Mike Krieger · 8th August 2007, 17:53

I have always suspected that bad separators are a contributor to carbon build up in the heads. When they go bad the entire plenum gets sprayed with oil and I have seen puddles of oil in mine before I changed out the separators. When that gets sucked in and doesn't burn completely, I think it coats the combustion chamber and backs up into the ports in the head and blocks the secondary air passages.

richie_rvf · 8th August 2007, 18:38

Max,

was that the price each or for both?

Sounds like it would be a good idea to replace them seeing as how they are so in-expensive regardless of oil consumption.

Cheers for the feed back,

Richie.

maxm5 · 8th August 2007, 18:46

Richie

That was for both.

Max

Silver_Menace · 8th August 2007, 22:24

Are these oil separators something that could be cleaned at regular intervals with petroleum distillates? I surmise the answer is no without seeing the interior of an oil separator. It's not a horrible price for piece of mind.

Ken21 · 8th August 2007, 22:53

My beast consume around 1L/600km for the past few months and i also think it is the oil seperators so i just ordered both oil seperator and all new hose for it and hope it will return back to normal

maxm5 · 9th August 2007, 09:37

Silver
I guess you could clean them out, though being a sealed unit there may be some internals that you can't get at to clean. If I get the chance I'll cut the old ones open and take a picture of the x-section.

Ken - If you DIY, then the hard part is gettin the bottom hoses back on.

Max

derheilige82 · 11th August 2007, 19:05

Any updates on the consumption or new observations?

maxm5 · 13th August 2007, 10:11

Derheilige

No change in the last five days - covered another 800 miles or so and the oil consumption seems to have settled down at 1L per 1,000 miles.

Max

100%Cocoa · 13th August 2007, 14:02

Quote:

Originally Posted by maxm5

Silver
I guess you could clean them out, though being a sealed unit there may be some internals that you can't get at to clean. If I get the chance I'll cut the old ones open and take a picture of the x-section.

Ken - If you DIY, then the hard part is gettin the bottom hoses back on.

Max

I'm told it's just a simple vortex arrangement inside so you can just blow them through with an air line. My oil consumtion is so high this is my first job for next weekend!