Engine - Missing/Rough idle/Noise
Number 87-6 (Gasoline)-44A Date 7/87Subject: CYLINDER HEAD EXHAUST VALVE GUIDE WEAR
1987 GRAND AM, FIERO, AND 6000 MODELS WITH 2.5L L4 ENGINE (VIN CODES R AND U)
Some 1987 vehicles with 2.5L L-4 engine may experience worn exhaust valve guides in the cylinder head. An engine with this condition may exhibit valve train noise, missing, and a rough idle. This condition could be caused by puddled chrome on the exhaust valve stems, which results in a rough surface and accelerates wear.
If an engine exhibits these symptoms, measure valve stem-to-guide clearance of all exhaust valves. If one or more exhaust valve guides in the cylinder head are worn to the point where clearance is .004" to .006", ream all these valve guides to the appropriate oversize diameter, recondition all exhaust valve seats, and replace all four exhaust valves with the correct oversize valves as described in the service manual. If oversize valves are not available, replace the cylinder head and all four exhaust valves with standard size valves.
If one or more exhaust valve guides are worn enough that stem-to-guide clearance is .007" or greater, replace the cylinder head and all four exhaust valves with standard size valves.
EXHAUST VALVE PART NUMBERS
P/N 10044612 - Standard Size Stem
P/N 10044613 - .003" Oversize Stem
P/N 10104418 - .005" Oversize Stem
CYLINDER HEAD PART NUMBERS
P/N 10049099 - Grand Am Model - L68 P/N 10049100 - 6000 and Fiero Models LR8
All engines have a build sequence number on a large bar code sticker located on the exhaust manifold side of the cylinder block above the oil pan rail. Engines having numbers higher than the following, which appear on the sticker, should not exhibit premature exhaust valve guide wear:
Sticker
Model Number
6000 0378434
Grand Am 6188498
Fiero 3200559
Use applicable labor time and operation number.