For 1990-2009 cars

# ROTTEN EGG ODOR FROM EXHAUST DIAGNOSTIC SERVICE PROCEDURE

#### SUBJECT: "ROTTEN EGG" ODOR FROM EXHAUST

#### MODELS AFFECTED: 1986-1987 DE VILLES, FLEETWOODS, ELDORADOS, SEVILLES, BROUGHAMS, AND CIMARRONS

This bulletin supersedes T-87-124B. This bulletin is being revised to include new part numbers for DeVilles, Fleetwoods, Eldorados, and Sevilles.

Some 1986-1987 DeVilles, Fleetwoods, Eldorados, Sevilles, Broughams, and Cimarrons may experience a "rotten egg" odor from the exhaust system. If present, the odor will be most evident during idle conditions.

To address this condition it is important to first check those items which may cause a vehicle to run excessively rich. These include, but are not limited to:

o Check for normal operating temperature o Check for excessive fuel pressure o Check for incorrect idle speed o Check for incorrect engine timing o Check for leaking fuel-injector

Refer to the appropriate model Cadillac Service Information Manual, Section 6E-B "Excessive Exhaust Emissions (Odors)", for more information.

DeVilles, Fleetwoods, Eldorados, and Sevilles:

If proper vehicle operation is verified and the odor condition persists, install a new catalytic converter (refer to part numbers listed) using the following procedure. Refer to Figures 1 and 2.

1. Raise the vehicle and support the catalytic converter.

2. Disconnect the AIR hose from the converter.

3. Using tool J-35976, BT-8252, or equivalent, cut the intermediate pipe at the converter as close to the weld as possible. Refer to Figure 2.

4. DeVilles and Fleetwoods - Cut the exhaust pipe at the converter as close to the weld as possible. Refer to Figure 2. Eldorados and Sevilles - Remove the two bolts and springs from the exhaust pipe to converter flange.

5. Remove the catalytic converter (and seal on Eldorados and Sevilles).

6. Collapse and remove the portion of the catalytic converter inlet/outlet remaining in the intermediate pipe (and exhaust pipe on DeVilles and Fleetwoods).

7. Install the new catalytic converter. The converter inlet/outlet will fit inside the existing pipes.

8. Eldorados and Sevilles - Install a new exhaust pipe to converter seal, P/N 1633384. Install the exhaust pipe to converter flange bolts/springs and tighten to 20 N.m (15 lbs. ft.) torque. DeVilles and Fleetwoods - Instill a guillotine-type clamp, P/N 15595048, at the exhaust pipe to converter fitting. Tighten to 35 Nm (26 lbs. ft) torque.

9. Install a guillotine-type clamp, P/N 15595048 (except C-touring use 3634476), at the intermediate pipe to converter fitting. Tighten to 35 N.m (26 lbs. ft.) torque.

10. Reconnect the AIR hose, lower vehicle, start engine, and check for exhaust leaks.

PARTS LIST

Part Name Model P/N ------------------- --------------- -------- Catalytic Converter DeVille/Fleetwood 25128764 Catalytic Converter DeVille Touring Coupe/Sedan 25103959 Catalytic Converter Eldorado/Seville 25128765

Broughams and Cimarrons:

If proper vehicle operation is verified and the odor condition persists, install a new catalytic converter using the part numbers listed below:

#### Model P/N

1986-1987 Brougham federal emissions) 25103919 1986-1987 Brougham (California emissions) 25103918 1986 Cimarron 25104705 1987 Cimarron 25104025

Parts are currently available from GMSPO.

WARRANTY INFORMATION VEHICLE SERIES Operation --------------------------- Operation Description Number c D E J K V --------------------- -------- - - - - - - Converter R&R T5141 .8 .8 .6 .3 .6

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.