Heater Core - Intermittent Moaning Noise
85ford03 Article No. 85-3-3HEATER - CORE - INTERMITTENT MOAN - 5.0L ENGINE
FORD 1985 THUNDERBIRD
LINCOLN-MERCURY 1985 COUGAR
A moan which is emitted from the heater core when the engine is operated above 2300 RPM may be a vibration caused by high coolant velocity. To service, perform the following diagnostic test procedure. Diagnostic Test Procedure
1. Start the engine and accelerate to approximately 3000 rpm to verify the heater core moan conditon.
2. If a heater core moan sound occurs, stop the coolant flow by clamping the heater core inlet hose with a "C" clamp or locking pliers applied with protective pads on the hose.
A. If the heater core moan sound does not stop after stopping the coolant flow, refer to the Noise, Vibration and Harshness (NVH) Diagnosis located in the 1985 Car Shop Manual.
B. If the moan sound is stopped by clamping the heater inlet hose, stop the engine, remove the clamp, and install the water flow restrictor in the heater core inlet hose as outlined in Step 3, Water Flow Restrictor Installation Procedure.
3. Water Flow Restrictor Installation Procedure
A. Loosen the radiator pressure cap.
B. Loosen the heater inlet hose clamp at the heater core tube and disconnect the hose from the heater core tube.
C. Insert the water flow restrictor (Part Number E1DZ-18D358-A) into the end of the heater inlet hose so the larger diameter hole - on the restrictor - is facing the direction of flow, and a minimum hose end-to-restrictor clearance of 1-1/2 inches is provided.
D. Reinstall the inlet heater hose on the inlet heater core tube and tighten the hose clamp to 16-22 in. lbs. torque.
E. Check and add coolant to the cooling system as required as outlined in Section 27-01 of the Shop Manual.
F. With the radiator pressure cap installed, operate the engine check and correct for
coolant leaks at the heater hose connections. Run vehicle long enough to discharge any air from the heater core. Make sure the engine is warm enough to open the thermostat.
PART NUMBER PART NAME CLASS
E1DZ-18D358-A Restrictor AG
OTHER APPLICABLE ARTICLES: None
WARRANTY STATUS: Reimbursable within the provisions of the Warranty and Policy Manual.
OPERATION: SP18476A84
TIME: 0.4 Hr. DLR. CODING: Basic Part No. 18476 Code: 56