Hot Bearing trip on “Deep Rolled” engine after overhaul

[Anonymous]

We have experienced a hot bearing trip on one of our 20V34SG engines that had the “Deep Roll” procedure performed on it just 29 operating hours after the 16K maintenance.  This is our third 16K and second with the “Deep Roll” procedure.

Anyone else experience something like this on a “Deep Rolled” engine?  We are hearing of a cracked shaft in NM.  I am looking to get some particulars on any issues.  As usual, Wartsila is mum.  Thanks

[Anonymous]

Richard,

Sorry for the delayed response, but we had a shutdown on high main bearing temperature, and found the cause to be a cracked shaft.  I can provide more details, but following is the way it showed up:  We had recently had a shutdown on high liner temperature, cyl 6A.  It was replaced with no identified cause.   After 21 hrs of runtime, we had an the engine trip on a high main bearing differential trip – Bearing #7 (adjacent to cyl 6A).  Found crankshaft cracked completely through.  The crack caused a local loss of oil pressure, starving cylinders 6A & 6B of oil, resulting in liner scoring. Main bearing 7 was affected as well, due probably to oil pressure and shaft alignment, since it was broken.  The crack ran directly through a repaired spot in the shaft where it had been ground and polished…prior to deep rolling.  The deep rolling tool could not properly deep roll that area because of the uneven surface where grinding took place.  This was determined to be the cause of failure.

Stephen Layton

[Anonymous]

Thank you Stephen.  We did not have any grinding on this bearing, but did need the deep rolling.  We are finding that there is odd wear in the bearing caps on our 16K and are having the shaft polished to even out the faces.  We did that on one other engine so far and only have two engines that had the deep rolling done.

[Author]

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