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ISX15 and QSX15 Liner Lobbing and Piston-Liner Change History TSBs
I did not see this Cummins TSBs posted elsewhere - so here they are:
One is about a defective Liner machining process causing excessive oil consumption;
the other TSB is about the changes (history) of the Piston and Liners (1998 - Current).
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The defect described in the first TSB is do to a manufacturing defect of the liners themselves. The liners are made in China by a Wisconsin supplier named Menominee. The liners are then shipped to Menominee in WI and machined. The problem is the were using a 3 stone hone on the liners which left a lobing pattern of high and low spots that would then cause oil consumption. This oil consumption woul happen early life and be noticeable before 50K miles of delivery of truck. The supplier ran into supply issues keeping up with demand and perhaps used a cheaper hone or sped up the process which caused the issue. The curious thing is, when they fell behind, they asked their Chinese supplier to help out be doing some honing in China. The Chinese used a 6 stone hone and suffered NO lobing issues. Anyway when the liners were supplied to Cummins there was no distinguishing which liners we WI Vs China honed. You could have had an engine with liners from both in one engine. Cummins has no quality control process for determining which supplier honing process was used so its possible to have two engines built in a row with all Chinese, all Wisconsin or a mixture during this time.
So, if you have early life high oil consumption it is NOT carbon packing. It is probably liner lobing and should have the liners replaced. You also want them to replace the pistons to the new "APR" (Anti-Polishing Ring" style piston liner to avoid future Carbon packing issues.
Also FYI , the 2010-2013 built ISX15 engines suffered terrible fuel pump failure rates due to ceramic plunger failures in the fuel pump due to debris in the oil due to a poorly designed oil bypass valve that would stick open and allow unfiltered oil through.
And the Camshafts were prone to damage from having too much of a crown on the rollers leading to high stress there and poor roller bearing materials that would degrade and oxidize causing them the hang or stutter thus causing the oil film to be scraped off the camshaft and scratching it. Once scratched, the cam would eventually beat on that scratch until it flat spotted.
So if you have one of these engine apart for rebuilding, you want to be aware of the issues and be sure to get the updated parts and thoroughly inspect your fuel pump and cam.
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