Ford Expedition 4.6L - OR - 5.4L Engine

Hello all,

Was wondering which engine you thought was better/more reliable. The 4.6L, or 5.4L for the Expedition. I won’t be doing any towing, just people transport. Looking to buy a used one in the 2003/2004 year range.


The 4.6 has enough guts to move the Expedition along just fine. It won’t be a race car, but neither will the 5.4. If you won’t be doing any towing, are you sure that the Explorer isn’t big enough for your people hauling needs? Or maybe a large station wagon?

I have an '05 with the 5.4L engine. No matter what you go with, the fuel mileage will poor. If you drive mostly in the city (stop and go) the mileage will be horrible. There is a reason my brother parks his 2004 Expedition at home and uses his wife’s Escape for around town driving.

Now off that soap box, the Expedition is a capable people mover. If you do freeway driving with a full load of people, you may want to consider which engine will be working less. The 5.4 typically will get poorer gas mileage. But if the vehicle will mostly be loaded down with a full load of people, then it will be working less hard than the 4.6L and therefore may get comparable fuel mileage. 6 one, half dozen the other.

According to, the difference is 1 MPG. Pick the one that meets your needs. If you aren’t towing, the 6-cyl should be just fine.

They are both V8’s. The 4.6L is similar to the one in the Mustang GT.

One is as good as the other. Much depends on how it was treated by the previous owner and will be treated in the future.
Two potential problem areas are a spark plug blowing out of a cylinder (often caused by overtightening of the plug in the past) or an oil filter adapter flange leak. The latter is not a serious deal if it’s ever needed.

The former is more serious so removal of the plugs is not a bad idea. This would allow inspection of the plug threads to see if there is any aluminum hanging on them and also to see just how tight they were. Allowing plugs to remain in place for long periods of time will cause them to gald in the threads. When the plugs are finally removed they can sometimes bring part of the threads with them.
Just pointing out something for consideration anyway.

The 4.6 in my Lincoln has about 217k miles on it and the engine has never been touched. It uses maybe? a small palmful of oil between changes but it’s so slight as to be near undetectable.

Parts may even be cheaper for the 4.6 but I don’t really know about the availability difference between the two but the 4.6 is everywhere.

Both engines are basically identical mechanically, so reliability should be the same either way.

To prevent this from happening, use anti-seize compound on the spark plug threads. This prevents the threads in the head from galling. This happens when galvanic action between the steel and aluminum (dissimilar metals) lock together, similar to micro-welds. My preference in Permatex Anti-seize, which is silver in color. Even after 65K miles in my Ford 4.0L, the plugs came out with no resistance or problems.

BTW, I learned this from a machine shop mechanic after he heli-coiled a VW cylinder head for me. That was 22 years ago. Used that advise ever since, and never regretted it.