Exhaust - Hissing and Puffing Noises

NO: 11-04-94 Rev. A

GROUP: Exhaust

DATE: Oct. 28, 1994

SUBJECT:
Exhaust Noise

THIS BULLETIN SUPERSEDES TECHNICAL SERVICE BULLETIN 11-04-94 DATED JUL. 1, 1994 WHICH SHOULD BE REMOVE FROM YOUR FILES. THIS BULLETIN ADDS PARTS AND ADDITIONAL CONDITION AND FAILURE CODES. CHANGES ARE HIGHLIGHTED WITH **ASTERISKS**.

MODELS:

1995 (PL) Neon

NOTE:
THIS BULLETIN APPLIES TO VEHICLES BUILT PRIOR TO APR. 24, 1994, MDH (04-24-XX).

SYMPTOM/CONDITION:

Exhaust noise that can be described as a "hissing" or "puffing" sound on acceleration or under moderate to heavy engine load, coming from the front of the vehicle. **And/or a squeak/chirp noise may be heard on engine start up or shut down or when shifting gears.**

PARTS REQUIRED:

**1 4546818 Exhaust Seal Ring**
**2 4427299 Exhaust Flange Springs**

REPAIR PROCEDURE:

This bulletin involves **replacement of the exhaust seal ring and exhaust flange springs** and sizing of the catalytic converter inlet pipe to provide a better fit of the exhaust seal ring.

1. Raise the vehicle on hoist and disconnect the downstream oxygen sensor connector.

2. Remove the two shoulder bolts, springs and nuts retaining the front catalytic converter pipe to the exhaust manifold. **Discard old springs.**

3. Loosen the clamp between the catalytic converter and the intermediate exhaust pipe and remove the catalytic converter from the vehicle.

**4. Replace the seal ring with revised P/N 4546818.**

5. With the seal ring in place on the catalytic converter inlet pipe, use a manual multisegment pipe expander to round-up the inlet pipe diameter of the catalyst so that the seal ring is "snug" to the pipe. The seal ring should still rotate on the pipe, but not spin freely. Expand only the first 13 mm (approx. 1/2") of the inlet pipe.

NOTE:
BE CAREFUL NOT TO EXPAND THE PIPE TOO FAR AS THE SEAL RING COULD CRACK. SHOULD THE SEAL RING CRACK, BOTH THE CATALYTIC CONVERTER AND SEAL RING WILL HAVE TO BE REPLACED. A HYDRAULIC PIPE EXPANDER IS NOT RECOMMENDED FOR THIS PROCEDURE.

6. Install the catalytic converter to the vehicle and install the inlet pipe to the exhaust manifold, **using new springs, P/N 4427299.**

7. Connect the downstream oxygen sensor connector.

POLICY:
Reimbursable within the provisions of the warranty.

TIME ALLOWANCE:
Labor Operation No: 11-20-05-93 0.5 Hrs.

FAILURE CODE: **EN - Exhaust Noise or SX - Seal Squeak**