Fuel Tank - Popping/Thumping/Grinding

^ FUEL TANK - MIDSHIP - "POPPING, THUMPING OR MUTED GRINDING" NOISE FROM UNDER THE TRUCK

^ NOISE - "POPPING, THUMPING OR MUTED GRINDING" FROM UNDER THE TRUCK
Article No. 89-20-12
LIGHT TRUCK: 1988-90 F SUPER DUTY, F-150, F-250, F-350
ISSUE: Popping, thumping or muted grinding sounds may come from beneath the truck. These noises are caused by a stick-slip effect between the midship fuel tank mounting surfaces and the fuel tank.
The midship fuel tank is mounted with insulating strips to suppress noise. These insulators are faced with mylar to assure that a non-sticking surface is in contact with the fuel tank. Sometimes, the mylar may become contaminated by a small amount of asphaltum from the main part of the insulating pad. This cancels the beneficial effects of the mylar. Then, normal driving movements can result in creating the noises described above.

ACTION: Use the following service procedure to clean the mylar mounting surfaces.

1. Lower the midship fuel tank approximately 6 inches. Refer to the appropriate Truck Shop Manual, Sections 24-50 (Gas) Or 25-50 (Diesel) for service details.

2. Clean all of the mylar mounting surfaces with Ford Tar and Road Oil Remover (B7A-19520-AA).

3. Clean the contacting surfaces of the fuel tank with Ford Tar and Road Oil Remover.

NOTE: THE CLEANING MUST BE DONE THOROUGHLY. THE CONTAMINATION IS NOT ALWAYS APPARENT IN A CASUAL EXAMINATION.

4. Re-mount the fuel tank. Refer to the appropriate Truck Shop Manual, Sections 24-50 (Gas) Or 25-50 (Diesel) for service details.

PART NUMBER PART NAME CLASS

B7A-19520-AA Tar & Road Oil Remover B

OTHER APPLICABLE ARTICLES: None
WARRANTY STATUS: Eligible Under Basic Warranty Coverage

OPERATION DESCRIPTION TIME
892012A Clean Fuel Tank Mounting 0.9 Hr.
Surface

DEALER CODING
BASIC PART NO. CONDITION CODE
9240 49
OASIS CODES: 4500, 7100, 7113