1997 5.4 questions...

[johnboneske]

Can a 4.6 be swapped for a 5.4? direct swap? my passenger side exhaust manifold has a broken stud and is leaking...I saw that ford had a service bullitin for it, but no recall on bad bolts. It now has 167000 miles on it, but the body is perfect. Know of an "easy" fix to the exhaust manifold, or should I buy a used engine, say with 100k or less on it, and put headers on it...have to replace exhaust manifolds anyways(since one is now warped from broken bolt and driving it), and headers will offer better performance...Wondering if putting in a 4.6 would improve mileage. I get about 14.5 MPG on a good day with my 5.4 and 3.73 gears. or anyone know how to improve milage? Any help would be appricated!!

 

[97_edition]

Can a 4.6 be swapped for a 5.4? direct swap? my passenger side exhaust manifold has a broken stud and is leaking...I saw that ford had a service bullitin for it, but no recall on bad bolts. It now has 167000 miles on it, but the body is perfect. Know of an "easy" fix to the exhaust manifold, or should I buy a used engine, say with 100k or less on it, and put headers on it...have to replace exhaust manifolds anyways(since one is now warped from broken bolt and driving it), and headers will offer better performance...Wondering if putting in a 4.6 would improve mileage. I get about 14.5 MPG on a good day with my 5.4 and 3.73 gears. or anyone know how to improve milage? Any help would be appricated!!

What I have heard is you will not get better gas mileage with a smaller engine. Because the Expy's are so big the smaller engine has to work harder. My assumption would also be that if you have been driving a 5.4 and switch to a 4.6 you will not be happy with the decrease in performance and end up pushing the engine harder anyways.

Sorry, I can't offer any good advice on the manifold. My 97 5.4L expy had passenger side manifold replaced a week before I bought it. (The old one was cracked so I was told.)

 

[jeff1998]

I cannot say for an Expy but I had a 97 F150 with the 4.6 and it labored to pull it decently. My mileage was about 14 with it. I now have a 98 Expy with a 5.4 and is has plenty of power. The Expy is heavier than an F150 so it would work even harder.

My pass side stud is broken also. It really does not affect it that much. It does leak a little when cold but when it warms up the manifold warps itself shut again, no leak. A good mechanic should be able to get the broken stud out and replace it.

 

[mmrseed]

um, yeah I never owned a 4.6L but I test drove a 4.6L f150 and it was the slowest dog I ever drove. I cannot imagine that even non enthuiasts could be satisfied with that engine option. While I symathize about gas consumption I could not see spending the money for an engine swap for a smaller engine which may face similar problems in the not to far future