For 1990-2009 cars

# DIESEL CRACKED CYLINDER HEAD CRACKS IN VALVE SEAT AREA

#### Models Affected: All Equipped With Diesel Engines

We continue to hear about diesel cylinder heads being replaced because of cracks between the intake and exhaust valve seats. Cracks in the seat area are normal for both 5.7L and 4.3L diesel as well as some other diesel engines produced by other manufacturers. Many cylinder heads that have been returned to Buick have been examined and the cracks are superficial. The coolant is approximately 5/8" away from the crack and therefore will not result in a loss of coolant or compression.

General Motors bulletins are intended for use by professional technicians, not a "do-it-yourselfer". They are written to inform those technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions and know-how to do a job properly and safely. If a condition is described, do not assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See a General Motors dealer servicing your brand of General Motors vehicle for information on whether your vehicle may benefit from the information.