Ring gap m54

[harrier]

This is not a FI topic, but there is no rebuilder thread, and I hope you all can help

I am rebuilding an M54b30 with about 95k. Before you comment, I bought the engine used for $300 and figured I would learn how to rebuild.

Bores measure out great, with .4 to 1.2 (max) thousands of a millimeter wear.

I wanted to run m52tu oil rings to minimize oil burning, so I bought two sets of rings, one Mahle b30 and one Goetze m52tu. The Mahle ring gap is perfect - just a hair off the low end of the permissible range.

The m52tu oil rings, however, have a huge gap - .9mm at the lowest point of ring travel in the bore. These are brand new just out of the packaging. Any thoughts on why this would be happening? M52 bore diameter is 84mm, identical to m54

[5mall5nail5]

Do yourself a favor and measure the flatness and twist of the block itself. If its an aluminum M54 they can actually warp and twist. I have one as a coffee table for this reason.

[harrier]

I measured the flatness and it is spot on. Same with the head. Took the head to a machinist to confirm and he was shocked that it had no deviation at all.

[harrier]

Turns out the rings were manufactured undersized. ECS took the, back and swapped with Mahle brand. Gap is perfect now!