Info - Revised 6.5L Diesel Rocker Cover Sealing Procedure

This bulletin is to inform dealers of a new stepped rocker cover rail design being introduced into production approximately May 1999 on the 6.5 L diesel engine. The new rail design will enhance sealing of the rocker cover to head. This rocker cover will also be used in service applications when the old style rocker cover supply is depleted.

The stepped rail design requires a slight modification to the RTV application procedure when resealing the cover. After cleaning the sealing surfaces of the head and rocker cover, apply a 5-8 mm (3/16 -- 5/16 in.) bead of RTV sealant (1) (GM P/N 12346286) overlapping the stepped area of the sealing surface, inboard of the bolt holes.

The RTV must be applied so that it follows the stepped ridge and is distributed evenly on both the upper and lower levels of the step. When fastened to the cylinder head, the RTV should fill the gap area (1). The sealant must be wet to the touch when the bolts are tightened.

Important: As with any stamped steel cover, care should be taken to avoid distorting the sealing surface when removing or cleaning the cover during service.

Tighten
Tighten the bolts to 27 N·m (20 lb ft).

Service Manual procedures will be updated to reflect this new design.

Parts are currently available from GMSPO.