My engine is quickly going out in my 2008 Ford F-150, I already bought a new truck and I was going to give it to my son.

Well it took a turn for the worst where at low speeds it will stall, something about the timing chain and the oil pressure is down (according to the mechanic). Well my son is disappointed (which I would be if I was him) but he says he will buy it from me for $1 and put a new engine in himself. Then he asked me if he could put a 4.6L engine where there was a 5.4L engine.

Well I have no clue, so that's why I'm here. Will the engine mount line up? Would we have to do anything to it or will it be a matter of putting it in and hooking it up.

I'm positive he won't be pulling a heavy load anytime soon except putting his dirt bike/ quad in the bed to go to his friends house.


Is it a good idea? Thanks!

 

what was the outcome of your motor swap did it work?

 

I realize this is a dead thread, but to answer the question, yes it's doable.
I put a 4.6l from a 09 Crown Vic into my 07 F150 FX4 and it's working fine, some issues with the engine not having the variable valve timing, I had to hook up the old vct's and connected them together with a short length of heater hose (just so they would stay clean and not get in the way of anything) so the computer thinks they are hooked up, and one of the cam position sensors isn't hooked up since none is there, a Tuner could take care of that by disabling the phasers if it bothered me enough.
Other wise it runs well and I like it. I bought the truck at auction for cheap as they advertised it with noisy phasers, and took it apart expecting the worst, and my suspicions were realized. The reason I went this route was because as I researched the 5.4 I kept reading of the problems with the tensioners, the sparkplugs, the inability to replace camshaft bearings as there are none.
It's funny cause I was initially so relieved to be able to remove the sparkplugs as they were Autolites, only then to find out that it was slowly dying of a shredded right side camshaft due to low oil pressure, 3 lobes on the second cylinder were ground right down, the leaking cam chain tensioners on both sides ended up starving the right side of oil pressure, which I found out is common from the rebuild shops I called.
Both sides the seals were blown out, so rather than rebuild or buy a rebuild that could have the same issue, I needed time to figure out how to fix the 5.4 properly, or possibly convert to a better engine or ideally a diesel.
I used the torque converter from the Crown Vic, higher stall speed so the smaller motor can pull better.

So the 4.6 was a compromise so I could use the truck in the meantime and take my time with the rest. I got a decommissioned cop car for $800.00 plus tax, after selling off the wheel, doors, glass, and scrap steel and aluminum, oh yeah, and the catalytic converters, I actually made money and still have the front steering rack for use later in a hot rod build if I want.

Just a fyi, I bought another 5.4 for parts to get the heads, or just a cam, and that engine also had both timing chain tensioner seals blown out as well, just a poor design, so I may rebuild my engine and see if I can figure out a better sealing method for the chain tensioners, so the little seals they use couldn't blow out again.
And I am going to look into finding babbet bearings and machining the cam journals so they will accept the added size, this would make the heads rebuildable.