Service bulletin 1HDM5V2A05

A bulletin is a manufacturer's communication to its dealers, as NHTSA indexes it. The summary is NHTSA's. The document is the manufacturer's: read it at NHTSA. A bulletin is not a recall, and listing a model year does not mean every vehicle of it is concerned.

NHTSA's summary

TECH ARTICLE TA0023: TA0023: Crankshaft Rod Bearing. Purpose: Technicians have been falsely identifying connecting rod bearings as failed due to a perception of resistance as the rods are rotated. The clearance of the Twin Cam and Milwaukee-Eight® crank pin bearings are maintained to a very tight range. This optimizes performance and maintains low mechanical noise in operation. The connecting rod bore can also distort slightly in operation due to stress relaxation. As a result, bearing clearance decreases due to the contact zone broadening and the load being distributed over more rollers. The combination of a bore being slightly out of round and reduced bearing clearance can result in varying degrees of resistance through the range of motion. Axial clearance is also tightly controlled for proper alignment. For these reasons, zones of resistance can be found when the connecting rods are rotated by hand through their range of motion. Resistance during rod motion, by itself, is not an indication of a performance or durability concern.

The document

• NHTSA's copy of the document (PDF)
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The document is the manufacturer's. This site does not hold it. NHTSA files a document at one of these two addresses; we have not asked NHTSA which.

Components

Transmission and driveline

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