Emissions - Low Pitched Moaning Noise
Bulletin No. 85-67File in Group 6E
Number 14
Corp. Ref. No. 8056003
Date March '85
SUBJECT: UNDERHOOD MOANING NOISE DUE TO CATALYTIC CONVERTER AIR CHECK VALVE HOSE
MODELS AFFECTED: 1985 (RWD) FLEETWOOD BROUGHAM
Some 1985 Fleetwood Broughams built before VIN broadcast number 003500 may experience a low pitched moaning noise during closed loop driving conditions. This condition may be caused by a restriction in the air hose which connects the AIR control valve and the catalytic converter AIR check valve, resulting in a resonance in the hose. The restriction may be caused by excess hose length which results in a kink at the preformed bend in the hose. If a kinked hose contacts the air conditioner evaporator housing, the noise is amplified and conducted into the passenger compartment of the vehicle.
FIGURE 1 - Evaporator Housing:
To verify this condition, inspect the catalytic converter AIR check valve hose. Look for either a kink at the preformed bend of the hose and/or the hose contacting the air conditioner evaporator housing (see Figure 1). If the AIR hose is found to be kinked and/or contacting the air conditioner evaporator housing, follow the procedure described below.
1. Remove the two plastic hose clamps from the air hose which connects the AIR control valve and the catalytic converter AIR check valve.
2. Remove the air hose.
FIGURE 2 - Air Hose:
3. The correct length of the air hose, with the preformed bend held straight, is 6 1/4 inches. Using a knife or razor blade, cut the AIR control valve end of the air hose to 6 1/4 inches (see Figure 2).
4. Install the hose on the vehicle being sure the hose is seated completely onto both the AIR control valve and the catalytic converter check valve.
5. Check for kink in the air hose. If a kink is still present, remove the air hose and trim enough hose from the previously cut end to remove the kink. Reinstall the air hose on the vehicle.
6. Reinstall the two plastic hose clamps.
For warranty purposes, use labor Operation No. T6117 at .2 hour.