REVISED:RESTRICTED EXHAUST PLUGGED CATALYTIC CONVERTER

VEHICLES AFFECTED: 1983 Vehicles Equipped With 5.0 Litre V-8 (VIN Code Y) Engine And Closed Loop Emission System

CONDITION

Some 1983 vehicles produced prior to March 10, 1983 and equipped with a 5.0L V-8 gasoline engine (VIN Code Y) may develop a restricted exhaust due to the catalytic converter becoming plugged. This can result in poor engine performance or a no start condition.

CORRECTION

Catalytic converter replacement may be required on vehicles suspected of having a plugged converter. With this bulletin, Oldsmobile is releasing a new converter kit package which includes the beads in the upper bed and a plug for sealing the lower bed after installing beads per instructions in this bulletin. Prior to installing the new converter, the proper diagnosis of a restricted exhaust is essential. The following is a recommended diagnostic procedure to determine if the exhaust is restricted.

A. Inspect the exhaust system for damaged or collapsed pipes and repair as necessary.

B. Remove air hose at left or right air manifold check valve and remove check valve. See Figure 1. When removing check valve, two (2) wrenches must be used to avoid twisting off air manifold pipe.

C. Use a low pressure gauge such as a fuel pump gauge and connect it to the air manifold.

D. Run the engine at 2500 rpm and note the pressure reading.

E. Any reading above 1.25 psi indicates a restricted exhaust.

CATALYTIC CONVERTER REPLACEMENT PROCEDURE

If the previous diagnosis indicates a restricted exhaust, the catalytic converter must be replaced using the following procedure:

1. Remove converter using procedures listed in the applicable chassis service manual.

CAUTION:

The catalytic converter beads contain platinum, and/or rhodium. Additionally, the beads may be finely coated with lead compounds. Therefore, precautions should be taken to minimize dust generation during the replacement procedure. These precautions include:

A. Catalyst dust should be controlled by wetting with water prior to bead removal as described in Step 2.

B. The use of a suitable dust mask, rubber gloves and safety glasses is recommended when handling catalyst beads.

C. Allow converter to cool before handling.

2. Stand the old converter upright on the inlet end and pour 16 ounces of water into the outlet end to control catalyst dust.

3. Using a hammer and chisel, remove the fill hole plug from the lower bed. (The smooth side of the converter is the lower bed side). See Figure 2.

4. Hold the converter over a clean pan (J-34155-2) and empty the catalyst beads by shaking. It may be necessary to tap the converter belt flange with a hammer to loosen the beads.

5. Pour the beads into a sifting pan (J-34155-1) and sift to remove undersized beads.

6. The new converter, part no. to be obtained from the Parts Information section of this bulletin, should be propped up at a 45 degree angle with the lower bed fill hole at the top.

7. Using funnel J-34155-3, pour the sifted beads into the lower bed of the new converter. If additional beads are required to completely fill the lower bed, it will be necessary to obtain a lower bed bead kit from the parts department. Excess beads from the kit should be saved in a clean container for future use.

8. Lay the converter down on a flat surface with the lower bed fill hole on top.

9. Insert the fill plug into the lower bed fill hole. The fill plug outer rim must rest against the converter body.

10. Insert the plug installer tool (J-34118) into the fill plug and tighten to 47 N.m (35 lbs. ft.). See Figure 3.

11. Install the converter on the vehicle using procedures listed in the applicable chassis service manual.

PARTS INFORMATION

Parts are to be obtained from WDDGM using the following part numbers. Removed parts are to be retained in accordance with the current Service Policies and Procedures Manual.

Description Part Number ----------- ----------- Converter with Upper Beads 25057007 (Includes Fill Hole Plug)

Lower Bed Bead Package* 25056895 (If Needed to Fill Converter)

Converter Front Exhaust Clamp 1259609 (If Needed)

A Lower Bed Bead Package, when used along with the beads removed from the old converter, will complete approximately 10 vehicles.

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.