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Ford Expedition or F-150 Spark Plug change (5.4 Triton)


I just finished up replacing the spark plugs on my 1998 Ford Expedition with the 5.4 Triton V8. (This was a pain in the @ss; I owned a 1990 Ford Thunderbird and I thought those were horrible). Anyways, after searching the internet I found some very good tips on several site forums. I used these tips along with some additional steps that I thought would definitely help make the task less stressful. The additional steps may seem extensive, but they help make the task much easier, and like I said, LESS STRESSFUL!

First off, don't bother relying on a store-bought repair manual like the one I own. The instructions are so vague, they pretty much just tell you to remove the coil packs and remove/replace the plugs.

The best method involves using a foam pad (or thick padded carpet) and setting it over the radiator and top of the engine. You'll need a stool or chair to secure your footing while lying across the engine bay on this.

You will need a good assortment of extentions and swivels in 1/4" & 3/8" drive if possible.

If done correctly, it should take between 1-2 hours.

First as usual, disconnect the neg. on the battery.


Lay the padding across the radiator/engine bay.



When doing this job you'll end up looking kinda like this.....(I recommend using something much more stable than this little stool I used).



Remove the plastic cover covering the throttle body. (Three 10mm bolts)





Remove power connection terminal cover on the passenger side near the battery (this pops off when you pull downward & out at the bottom of it)




Remove three 13mm nuts and the cables. (make sure you mark them so you put them back where they were). Next, remove the two 8mm bolts holding the entire assembly to the firewall. Pull away from the firewall. Now you will be able to have easier access to the #4 spark plug farthest back on passenger side. I feel that this is the hardest one to change.





Remove the three 8mm bolts & remove the plate that secures the power steering reservoir in order to access the #5 spark plug.






Replace each spark plug one at a time. On the driver side you may need to remove the two 8mm bolts securing the fuel rail. You may need to pull the fuel rail up and away slightly to clear the check valve and access the #6 spark plug. Make sure you blow away all debris before removing the fuel rail. You do not want anything falling into the manifold. This would be HORRIBLE! Also, only pull the fuel rail away as far as necessary to access/remove the bolt securing the coil pack and the coil pack itself. Debris (or a dropped coil pack bolt)could possibly fall into the manifold through the injector ports! Again, this would be HORRIBLE!

Attach a small section of hose to reach the hard-to-reach areas. You need to blow out the spark plug holes BEFORE you remove the plugs to prevent debris from falling into the cylinders. And yes, this would be HORRIBLE!



Also, make sure you coat the spark plug threads with anti-seize, and coat the inside of the boots with dielectric grease. This will prevent corrosion, heat damage, and prevent the boots from sticking on the next replacement. Gap the plug to specs (.054 for mine) before installation. Start threading the plugs in by hand by removing the ratchet from the extensions. Tighten plugs to specs (84-168 inch lbs./7-14 ft. lbs for my '98 Expy) with a torque wrench. - DO NOT OVERTIGHTEN!- The aluminum threads on this engine can be easily stripped or damaged. These engines already have a history of blowing out spark plugs without warning, so damaged/stripped threads would only increase the chances of this happening to YOU!


After taking your time and being patient, you will find yourself finishing up this job and feeling a great sense of accomplishment. Bolt all parts back up to where they were, and re-check all of your connections to include connections to the coil packs, injectors, and also inspect surrounding vacuum hoses to see if they were accidently disconnected when moving them around to access the spark plugs (the PCV valve kept popping out when I did mine).


Hinesight is always 20/20, but I'm pretty sure I could do this again in under 1 hour. Remember, take your time, be patient, be careful, and take a breather if you need it!










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