I am replacing my 2004 4.6L with a 2001 4.0L. I have the engine out of the 4.0L and I have to replace the 4.0L heads with my 4.6L SAI heads and I have the AB seal kit for that. I will take the new oil pump from the 4.6L engine and replace the old 4.0L one with it. I will replace the timing belt since the engine is on a stand. What else should I tackle while I have the engine out?

 

water pump, oil pan and crucifix seals, oil pick up tube and o ring. Check the cam lobes for excessive wear also

 

Swap the 4.6 crank?

 

If you swap the crank you also have to swap the rods, but yes I would. You'll need to do a dinkle ball hone on the 4.0 block. Keep the 4.0 pistons.

If you're swapping the crank/rods and you already have the engine apart I'd also put the money into a cam and lifters.

 

Change the front cover the 2004 doesn't have an oil cooler.
IDK if you can swap the plugs over to the 4.0 cover?

 

Why would I change the crank? I have a non running 4.6L being replaced by a running 4.0L engine. Should be just a simple drop in.

 

I don't have the engine apart. Just trying to do an engine swap with a few maintenance items, nothing deeper.

 

I have found that all of the pulley bearings go to $hit when a 100K-mile engine sits idle for more than a month. Some of the pulleys made noise, some of them silent with a ton of drag but all is well after a solid update of all the pulley bearings. 2 idlers, AC comp', tensioner pulley; alternator is the only 1 I haven't messed with.

 

Cause then you would keep the 4.6 displacement, just with a slightly higher compression thanks to the 4.0 pistons. But if you're not tearing everything apart then your prerogative. Just nice to keep the power IMO, depend he on what caused the lack of running for the 4.6.

 

Yeah, I think if I were doing it I'd swap the crank and rods and keep the 4.6 displacement. That would mean the ECM wouldn't need to be changed either.

You don't say why the 4.6 is going bye-bye, but unless there are known problems with it's crank journals i'd swap it. Of course I don't know your other limitations such as time and money, plus I recall from auto shop in high school 40+ years ago that if you go that deep you'd probably want to replace the crank and rod bearings, which could lead to machine work on the crank journals, yada, yada, yada.