[Raheal Akhtar]

My Car Mercedes Engine Code : M 111.945 C200 (20.020) year of make 1999 is having high Oil consumption.

I have to put 1 Litre every 800 Kms.

The Engine was taken off and mechanic believed the piston rings are worn out which were previously standard size i.e 89.9mm

I bought another set of new standard rings 89.9mm and put them in. The mechanic says there clearance to the cylinder wall is high so suggested to go oversize rings on stock piston, as the existing stock pistons are in good shape.

He will buff the cylinder and increase the bore size to allow new fitment to take place.

Hence, I am in the process of ordering +90.5mm [+0.5mm] oversize piston rings as oversize pistons are very expensive to replace

Will putting oversize Piston rings on existing Standard pistons and increase bore size create any issues ?

Is this a temporary fix to my oil consumption problem ? how many miles would i be able to get from an engine fitting oversized rings +0.5mm on a stock piston (standard 89.9mm) before it requires another engine overhauling.

Should i go for +0.25mm piston rings instead ?

Need urgent help from Engine Gurus.

 

[BenzManNow]

Hi Raheal,

I had a similar problem with another car I owned (a Honda) back when I was young and naive (as opposed to now when I am older and still naive lol). The problem I had was due to a timing belt break which resulted in my having the upper part of the engine (the valve assembly) completely rebuilt. Note: I did NOT have the lower part of the engine rebuilt at this time as it was too costly. When I got the car back it was running fine but for the first time since I bought the car new it was starting to burn oil. When I returned to my mechanic to ask him about this he told me it was a common thing to have happen with a higher-mileage engine when only half of the engine is rebuilt (wish he'd had told me this BEFORE he convinced me to rebuilt the valve assembly). Anyway, the point of my story is this: If you rebuild only the lower or upper half of a higher mileage engine you'll most likely wind up burning oil even after the repair is made. Think of an old container with an old lid. Now replace that lid and what you'll have is a new lid trying to form a seal agains an old container. Now I may be wrong on this point and you may wind up not having the same issue I had but I think it's worth broaching the subject with your mechanic and any other mechanics from whom you would like to get a second opinion (which in my opinion would be a wise thing to do). Again, it's been my experience that rebuilding only half of a high-mileage engine (ie. the lower or upper half) is never a good idea. If it were me and if I planned on keeping the car then I'd just splurge on either a total rebuild or purchasing a used lower-mileage engine (with some sort of warranty). I hope this helps in some way. Good luck.