HIgh Mileage Woes!! Frank’s Automotive Repair
Although some exceptions exist, most manufacturers of 1996 and newer vehicles specify replacing spark plugs at 100,000 -mile intervals. The exceptions might include 50,000-mile intervals on some domestic an dimport vehicles and 140,000 intervals on some hybrid vehicles.
But a technician becomes involved with a special set of conditions when a vehicle like our Ford Expedition rolls in with 155,00 miles on the odometer. Without a doubt, all of the spark plugs will need replacement, all spark plug wires will be seized to the spark plugs and the spark plugs will be seized into the aluminum cylinder head.
Removal Tips
When servicing the ignition system; keep in mind that spark plugs are now designed to not only last 100,000 miles, but also so be successfully removed at the same mileage. Unlike the Expedition’s standard original equipment spark plugs, modern spark plugs are plated with metals that resist seizing to aluminum cylinder heads.
But the real issue in spark plug removal is avoiding tearing the spark plug threads away from the cylinder head. Although tool manufacturers make spark plug thread repair kits, the difficulty with repairing threads is the lack of accesibility to the spark plugs.
Patience is always the key to removing seized spark plugs. Because the spark plugs now reside in a well drilled about 5″ into the cylinder head, it’s important to blow loose dirt out of the spark plug . As always, sagety glasses should be worn to prevent injuries to the eyes.
Next, soak the spark plug with high-quality penetrating oil and loosen the spark plug about one-eighth turn to allow the penetrant to soak into the carbon buildup on the lower spark plug threads. After soaking for 30 minutes, gently alternate between tightening and loosenign the spark plug. If the spark plug sill feels tight, apply more penetrant, allow it to soak as long as necessary and repeat the procedure until the spark plug frees itself from the cylinder head. These basic suggestions can sace you the potential problems of removing, repairing and replacing a cylinder head.
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