Question about 1998 Ford Expedition
The vehicle started missing yesterday so I changed the fule filter and this didn't solve the problem. I am now going to change the plugs and wires along cap and rotor but cant seem to find any of these are they burried deep???????
the spark plug gap is .054
This is at best difficult and if not done right can destroy your heads ( about $2700.00). My advice is to have the dealership take the risk. However, If you decide to change the spark plugs yourself you'll need to know a few critical things first.
The 5.4L has aluminium heads, there is a design flaw in that the thread depth is to shallow, only 4 or 5 threads. because of this it is EXTREMELY IMPORTANT to apply anti-sieze on the threads of each spark plug and torque the plugs to NO MORE THAN 14 LBS. Also, if the plugs have been improperly changed before, it is to late, and you will rip the threads out when removing the old plugs.
Still wanting to do it yourself? OK here is how it is done;
Each spark plug has it's own coil, you will need a 8mm socket to remove the retaining bolt. Then disconect the coil wires on the coil. pull out the coil assembly (coil and boot). they may be stuck a little so you may need to wiggle it out. Now you are ready to remove the spark plug. You will need a THIN WALLED 5/8in spark plug socket, at least one extension, and on the #3,4,7, and 8 spark plugs you'll need a universal joint. the holes that the spark plugs are in are machined very thght and I found that I needed to try several different sockets before I found one that would fit inside the hole. Remove the old plug. apply anti-sieze on the threads of the new plug and install. DON'T CROSS THREAD, THERE IS ON SECOND CHANCE! TIP.. replace the old rubber boot with a new one and apply a liberal amount of spark plug moisture protectant gel inside the boot, spark plug end, this will save you from spark plug mis-fire due to moisture in the future. Place the new boot back on the coil and place the coil/boot back into the spark plug hole, it may need some wiggeling. Replace the coil retaining bolt (anti-sieze), reconnect the coil wires. Now do this 7 more times.
In all honesty, take it to a Mechanic, because this is a real pain in the....
Best of luck, and I'm not responsible for any damages you do :(
Posted on Feb 24, 2009
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