Exhaust System - Noise/Air Pump Buzzing

88ford23

^ EXHAUST SYSTEM - "WHISTLING" NOISE AT TAILPIPE, "WARBLING" NOISE AT THERMACTOR AIR PUMP AND "BUZZING" NOISE DOWNSTREAM OF AIR CHECK VALVE - 5.0L EFI

^ NOISE - "WHISTLING" AT TAILPIPE, "WARBLING" AT THERMACTOR AIR PUMP AND "BUZZING" DOWNSTREAM OF AIR CHECK VALVE - 5.0L EFI

Article No. 88-21-3

FORD: 1988 THUNDERBIRD

LINCOLN-MERCURY: 1988 COUGAR

ISSUE: A "whistling" noise from the tailpipe, "warbling" noise at the thermactor air pump or a "buzzing" noise downstream of the air check valve at idle when the exhaust system is hot may be caused by the pulsation of the check valve diaphragm.

ACTION: Install a resonator-air pump assembly to muffle the noise. Refer to the following procedure for service details.


1. With engine at operating temperature, check for the noises.

FIGURE 1:

2. Locate the downstream exhaust air supply check valve on the right hand side of engine, Figure 1.

3. See if noise is coming from the exhaust air supply check valve area. The noise could be a "buzz" that comes and goes along with a vibration. Tapping the exhaust air supply check valve may cause the noise to stop briefly.

CAUTION: THE EXHAUST AIR SUPPLY CHECK VALVE MAY BE HOT!

4. Locate the air bypass valve inlet hose between the air bypass (dump) valve and the air control (diverter) valve, Figure 1.

5. Cut the air bypass valve inlet hose three inches from the air control valve, Figure 1.

6. Cut two inches off of the remaining long piece of hose, connected to the air bypass valve, and throw it away.

7. Install the resonator-air pump assembly (E8SZ- 9S458-A) between the cut hose. Install the two hose clamps (B7AZ-8287-C), Figure 1.

PART NUMBER PART NAME CLASS

E8SZ-9S458-A Resonator-Air Pump
Assembly C
B7AZ-8287-C Hose Clamps AM


OTHER APPLICABLE ARTICLES: None
WARRANTY STATUS: Eligible Under Emissions Warranty Coverage
OPERATION: 882103A
TIME: 0.4 Hr.
DLR. CODING: Basic Part No. 9A487
Condition Code: 56
OASIS CODES: 4400, 4600, 7100, 7113