1999 Ford Expedition from North America - Comments

Electronic odometer blanked out.

Power driver's seat stopped working.

Ball joints replaced.

Changing plugs and coils is a MISERABLE job.

Spark plug blew out of the head.

We dealt with the small problems because the vehicle served our needs well. We're all tall and my wife is a caterer and the vehicle is used for her work and for our road trips. The mileage (mpg) is bad but a worth trade off since we don't put many miles on the vehicle. The end of the road for us was when a spark plug exploded out of the head. Ours is a normally asperated (no supercharger) 5.4L model and when that thing went WOW!

Before the plug blew I attempted to change the spark plugs and coils (there's one coil per cylinder and it's on top of each plug) and the space is so cramped that I had to get a pro to finish the job. The engine is recessed into the firewall and there's not enough over head space to get to the rear most plugs. Lots of items must be removed to do the job. Back to the spark plug... The plug that blew is on the passenger side in the rear. THE most difficult to get to. It stripped out all the threads. I hired a mechanic to take a look and he, along with other mechanics, said the only way to fix it is to replace the head. Turns out Ford has too few threads on these heads and upgraded the heads on the 2001 models (8 threads on the 2001+ where as the older ones only have 4!). Although the problem typically happens on the superchaged 5.4L (Lightnings) all the mechanics said they'd seen this issue on the normally asperated ones too.

I'm getting rid of the vehicle.

Did the spark plug blow out because you tampered with it, and left it loose in its thread? Just a thought.

Spark plugs are very basic parts that extract and install in a basic way. I'm not sure how someone could tamper with them. I've worked on cars/trucks my whole life and perform maintenance, tuneups and basic repairs on all my vehicles. Right now my daily drivers are two old Volvos both with over 200,000 miles on them and both still getting over 25mpg hwy. So to answer your question, I feel comfortable there is nothing I did to cause a spark plug to rip 100% of its threads out of the head of the bone stock 5.4L engine while idling in traffic.

I replaced the plugs at 80k because I had studied the plug blow-out problem in detail. Yes, it's difficult to replace the plugs, it took me six hours, but I used a lot of extensions, sockets, part pickup tools, lighting, mirrors, and everything necessary to do it right. All of my plugs were fine, normal and minimal wear. The most important part of the job is to torque the plugs exactly to specifications. One of the main reasons that the plugs blow out is because water leaks past the coil boot and down into the plug cylinder where it cools the hot plug threads, constantly changing the thread metal expansion from cool to hot and back again; all of this causes the plug under compression to work itself loose. When you change those plugs, you need to coat the threads with anti-seize compound, torque the plugs properly, and then liberally coat the plug boot with dielectric grease to ensure it is water tight for long time. It's not a simple, straight-forward procedure; you need to take your time and do it right or you're just asking for a blown plug. So, one question I would have is 'did you torque the plugs correctly and to the exact value required by Ford?'

I am an mechanic and it doesn't matter what you drive, we still make money... whether it's a Ford, GM or Dodge, it is still something someone made, so someone like you can drive. If the world was perfect, I would be on welfare. Have a nice day.