SERVICE MANUAL UPDATE SEC. 6A1 ENGINE MECH. PISTON RING GAP

Subject: PISTON RING END GAP SPECIFICATIONS

Model and Year: 1989-91 GEO METRO

Figure 1 in this bulletin replaces Figure 112 in 1989/1990 GEO Metro Service Manual (ST370-89/ST370-90), or Figure 110 in the 1991 GEO Metro Service Manual (ST370-91). A discrepancy exists in the metric-to-English conversions. Use Figure 1 in this bulletin when performing piston ring end gap measurements.

FIGURE 1 MEASURING PISTON RING END GAP

ITEM STANDARD LIMIT ------------------- ---------- ------ TOP RING 0.20-0.30mm 0.7mm PISTON 0.0079-0.0118" 0.0275" RING END 2ND RING 0.20-0.30mm 0.7mm GAP 0.0079-0.0118" 0.0275"

OIL RING 0.20-0.60mm 1.8mm 0.0079-0.0236" 0.0708"

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.