New Special Tools (Go/No-Go Gauge P/No J43120 and J43481) Required for Cylinder Head Valve Guide #98-T-50 - (Jan 6, 2003)

1991 - 1999 Saturn vehicles

Purpose

This bulletin provides technical information regarding new special tools, Go/No-Go gauges P/Ns J43120 and J43481, that are required for cylinder head valve guide inspection.

Applications:

Diameter Specifications:

TOOL CARE:

Saturn Valve Guide Go/No-Go Gauges (P/Ns J43120 and J43481) are precision tools that allow technicians to quickly and accurately measure cylinder head valve guide bores for proper diameter, roundness, and straightness. This type of tool is commonly used in manufacturing for qualifying bores, sleeves, guides, etc. Precision tools must be used and handled with care. Do not drop, bend, score, scratch, or otherwise damage the gauge measuring pins or holder. Store the tools in a safe and secure location when not in use as described in the letter which accompanied the 7mm tool in a previous mailing. Also, lightly coat the gauge measuring pins with oil silicone lubricant to inhibit corrosion when in storage. If surface corrosion occurs clean the pins with fine steel wool.

Procedure:

1. With cylinder head removed from engine and valve removed from guide, thoroughly clean the valve guide using a drill driven guide brush and solvent.

Notice

The Go (Green) end of the gauge should go through the entire length of the guide with light and uniform pressure. Use of excessive force will result in tool damage.

2. Insert the Go (Green) end of the appropriate gauge (P/N J43481) into the guide from either the combustion chamber side or the camshaft side:
• If the gauge passes through the guide with light and uniform pressure, proceed to step 3.
• If the gauge will not pass through the guide with light and uniform force, clean the guide again as in step 1 and repeat the guide measurement. If the gauge still not pass through the guide with light and uniform pressure, refer to the appropriate model year Engine/Fuel/air Intake/Exhaust service manual for valve guide repair and/or replacement procedures.

  Notice

  The No-Go (Red) end of the gauge should NOT enter either end of the guide. Use of excessive force will result in tool damage.

3. Attempt to insert the No-Go (Red) end of the gauge into both ends of the valve guide:
• If the gauge does not enter either end of the guide, the guide is the within the correct specifications for diameter, straightness and roundness.
• If the gauge enters either end of the guide, the guide is oversized beyond specifications. Refer to the appropriate model year Engine/Fuel/Air Intake/Exhaust service manual for valve guide repair and/or replacement procedures.

GM bulletins are intended for use by professional technicians, NOT a "do-it-yourselfer".  They are written to inform these 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 your GM dealer for information on whether your vehicle may benefit from the information.

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