Oil in MAF 230k. engines.

[busby20]

I know this item has been covered in previous posts, and it was generally considered that the "oiling up" of the MAF on these engines was caused by the blockage of the small brass "breather" tubes which caused the oil to be forced back through the inlet manifold and polluted the MAF.

As this has been happening to my SLK's engine for some time now I decided to remove the manifold and "clean out" any carbon blockages in the pipe/s.

Hefting my trusty 4lb. mallet I carefully removed the manifold, and, lo and behold------------------the tubes were absolutely clear??--------big disappoinment! as I expected them to be completely bunged up and the answer to the problem would be solved-not!

The oiling was in the MAF and all the way back to the supercharger, and when I stripped of the air box there was about half a ltr. of black oil within it? so, looks like the oil is being drawn through the engine breather and into the induction system? This would suggest that there is a possibilty that there is leakage or back pressure within the engine block / head? however, the performance of the car is still within it's parameters? so, anyone got any ideas?

 

[television]

There are modified breather pipes, member Jim in Essex posted the cure, if you search it will come up

 

[busby20]

There are modified breather pipes, member Jim in Essex posted the cure, if you search it will come up

Hi Malcolm, yes I read through that post previously and I decided to carry out this work based on Jim's excellent post, however, unlike Jim's, the pipes on mine were completly free of carbon deposits (I noted that they were a differant shape from the ones that Jim showed in his pics. - maybe that was the modification and it worked?) anyway, the problem is not the pipes, and I was wondering if anyone else knew of any other scenario which would cause this problem,

 

[jamesmc]

Hi Busby20

I'd be reasonably convinced that a blockage in the lower part breather system is causing this. If not you may be into a more expensive mechanical repair.
No matter what anyone tries to tell you it will not be Supercharger oil.

You talk about the tubes being clear.

Can you confirm that the two brass nozzles built into the block are clear....... If they are blocked it's easier to clean them out rather than try and extract the existing ones.

Also, when I did the job, I swapped out the Valve 'T' Piece (MA111 010 00 91). The unit is factory sealed so I ditched it as there was no real way of checking how choked it was. If this was choking up you would also end up with back pressure in the system.

No matter what appears to be clear, or not, now you have the manifold off I would replace the lot anyway. None of the items are expensive, so on a DIY basis it's a cheap option.

BTW: Intake Manifold Bolts are torqued to 20Nm as recommended by MB.

More at: http://forums.mercedesclub.org.uk/showthread.php?t=34036