NOISE,MISFIRE,ROUGH IDLE INSPECT VALVE TRAIN

MODELS AFFECTED: 1987 CIMARRON

Some 1987 Cimarrons equipped with the 2.8L-V6 engine manufactured prior to September 8, 1986 (Julian Date 251) may exhibit unsatisfactory engine performance such as engine noise, misfire or rough idle.

To repair any of the above conditions, inspection of the valve train should be performed following an appropriate check of the ignition and/or fuel delivery systems.

Valve train inspection should include investigation for broken, bent or stuck valves and evidence of transfer and/or smearing of metal on the valve stems. If any of the above conditions are detected, replace both aluminum cylinder head assemblies and valves.

The top surface of each piston should be carefully inspected for evidence of contact with stuck valves. If evident, inspect the cylinder bore for damage resulting from loose or free moving metal particies that may have been dislodged by such contact. If no damage is detected, replace the piston, connecting rod and rod bearing in additional to the head assemblies.

If any damage to the cylinder bore is in evidence, installation of a partial engine assembly is required.

1. Head Replacement ----------------

Part Number Application Quantity ----------- ----------- --------

10048649 Head Assembly 2 (W/Valve Guides)

14091805 Valve, Intake 6

10070124 Valve, Exhaust 6

NOTICE: In addition, a cylinder head gasket kit will be required.

2. Partial Engine Replacement --------------------------

Part Number Application Quantity ----------- ----------- --------

10049091 2.8L-V6 Partial Engine 1 10048649 Head Assembly (W/Valve Guides) 2 14091805 Valve, Intake 6 10070124 Valve, Exhaust 6

NOTICE: In addition, all necessary gasket kits will be required such as:

o Cylinder head gasket kit o Oil pan gasket o Front cover and water pump o Miscellaneous individual gaskets as required.

3. Piston,Rod and Bearing Replacement ----------------------------------

Part Number Application Quantity ----------- ----------- --------

14100521 Piston W/Pin (Standard) 1 18008492 Bearing, Comm. Rod (STD) 1 476521 Rod, Piston (Connecting) 1 10077081 Ring Kit (STD) I

NOTICE: If more than one piston replacement is required, multiply quantity by the number of cylinders involved. If other than standard size parts are required, refer to groups 0.603 - 0.643 of S.P.O. catalogue.

For warranty purposes, use operation:

1. HEADS ONLY: J0517 for 9.5 hours ---------- 2. PARTIAL ENGINE: J1820 for 12.5 hours (ADD up to 2 hours to recondition all -------------- valves and ADD .4 hours if equipped with an automatic transmission)

3. PISTON, ROD, RINGS: One Cylinder: ------------------

Right Bank - J1300 for 7.7 hours (ADD up to 2 hours to recondition all valves) Left Bank - J1301 for 6.9 hours (ADD up to 2 hours to recondition all valves) Both - J1307 for 9.7 hours (ADD up to 2 hours to recondition all valves)

Refer to Labor Time Guide for additional piston replacement.

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.