NOT EXACTLY PURRRR--FECT !!!!
 

Hey ya'll

I am doing a out of frame in Atlanta at a decent shop useing only CAT parts in my 3406B and I told the shop to call me if there was any problems ??? I called there last nite and they allready (it's been there since the 28th of Dec !! ) got it allmost all back together n in the truck . But they had to cut a grove in the top of the block at the #6 hole and put a steel ring or spacer of some kind in because there was some-thing wrong with the top of the block where the top of the liner sits ???? Is this a bad thing ??? (the steel ring or spacer) Will it cause trouble down the road ??? The truck is not suppost to be finished until the middle of April so the time factor isn't important I just wish they would have called me because I might have changed the block out just to be safe ??? I need ya'lls input on this to ease my worry's about this ring !!!!

No thats fine they call that procedure counter boring. It allows the liner to sit at the proper height so the head gasket seals properly. Anytime I've seen it done they do all the cylinders though.

This was a fairly common repair. The liner moves in the block & wears it a little. Cummins would do the same thing on there engines. Done properly you should have no problems...

Upper counter-bore repair
 

My '03 C 15 had the same thing done when they had to do a head gasket under warranty. Very common and industry wide acceptable.

Note: Anyone with a C15 Cat with the prefix "6NZ" in the engine serial # beware of head gasket problems. The service writer said this series of serial #s are prone to head gasket problems. Luckily mine let go at 425k miles and was warranted. 165k since and no problems.
Just my .02 cents.