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malamu ... 4/25/2021

2002 Ford F-150 Lariat 8 Cyl 5.40L


Oil in driver side well under trim

I took off the trim in between the metal and carpet in the drivers side. In the well there is what looks like a small amount of motor oil. Where can it be coming from?

1 Answer


Jimm 5/1/2021

First question - how certain are you the fluid or substance is engine oil? Check the smell and consistency - there are other possibilities; anti-freeze (coolant) from the heater core or heater hoses.

Check the radiator and cooling system for the antifreeze condition - there should be no corrosion or rust visible inside the engine, hoses, radiator, overflow reservoir (tank), and heater core.

Check the cooling system for any leaks by a pressure test, at the radiator or coolant overflow tank. Local auto parts stores can loan a cooling system pressure tester for a small cost.

If any leak is found, repair, or replace as required. New hose clamps and new radiator hoses are inexpensive insurance.

Next step, flush the system with an off-the-shelf cooling system cleaner (caustic) then flush with fresh water, then refill with the correct 50/50 mixture of antifreeze and water.

In addition, the radiator and cooling system should be cleaned / flushed and refilled according to the manufacturer maintenance intervals; typically every 24-36k miles. Check the vehicle owners manual for the specifics.


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