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Originally Posted by leathermang
Another one of those deals where MB is different from all other cars which I have seen....They intend and expect that cross hatching to remain for oil supply to the rings or something....
If your bores were worn mirror smooth as you would expect of other engines MB would consider them worn OUT.
I have never heard of " choke " being called for in boring or honing a cylinder bore.... and MB certainly does not call for that.
I have heard of " choke " being produced by the differential pressure against the walls of the cylinder due to crank throw. But that is something measured and if too much is used as " needs reboring" measurement.
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You are right Leatherman about the cross hatching carrying oil. We recently had a job in our shop to re-sleeve 9 cylinder jugs for a huge air compressor. The low pressure jugs were 8 1/8" bore and the high pressure side was 7 1/16" bore. The jugs had to be bored over size to accept the new cans. After the new cans were installed they had to be bored to .004 undersize then honed to size. The factory recommendation for the finish surface was 70 grit stones. I thought they were nuts until I understood their line of thinking. The oil not only lubricates but it helps to seal the high pressure air on this beast. On car and light truck engines we are happy with a 280 grit stone for finish. I never saw a new Mercedes sleeve and I wonder what finish the factory uses.