So after the engine locked up on my 2001 SType I weighed the differences between rebuild and 4.0 swap. Then I stumbled on the 3.9 they put in the 2003-2006 Lincoln LS. For 1/4 the price I could get a 3.9 with 1 less horsepower. Not sure I would even be able to tell the difference. So after searching for a while I found a 2006 3.9 with 93k miles for $475.

I started on pulling the engine a couple days ago. I'm in no great hurry so it may take me a little while to get the swap done. I'll post what I can.

The main difference I noticed, with the exception of the intake manifold, was the idler pulley on the front cover. The 3.9 doesn't have one. Also it doesn't appear that the 4.0 has an EGR valve but I haven't gotten everything apart yet.

 

What about the VVT??? How are you going to address the missing VVT signals??? (input and output)

bob

 

The 03-06 LS has VVT. I know there are subtle differences in the heads. Hopefully there won't be enough so I won't have to swap the heads. I'll know more when I get the 4.0 out and the intake off.

 

You may find there are quite a few 'subtle' differences between the two engines besides an issue with the VVT solenoids.

Search the forum as this has been discussed before. I don't recall if the inlet and exhaust manifolds have the same mounting locations to match the Ford cylinder heads.

 

Years ago I bought some FELPRO cylinder head gaskets listed for a 2005 Ford 3.9 Liter.
I was going to install them on a Jaguar 4.0 V8 but they were too different to work. The gaskets would not line up with the block properly so I just abandoned the idea and bought the Jaguar gaskets.

I doubt the Jaguar heads will fit the 3.9 block if you cannot get the 3.9 to work as a block/head complete combination.

The 4.0 front cover might bolt on to get the correct idler location??

Good luck and keep us informed of the progress.

bob

 

I don't have the engine out yet but I decided to pull the intake to see if it's going to fit on the 3.9 and it does, sort of. The picture shows the 3.9 gasket on the 4.0 intake. As you can see the outside bolt holes don't quite line up. The holes on the 3.9 are further out than the 4.0.

This is where my 4 years as a machinist apprentice and 8 years in maintenance come in handy. I'm going to drill and tap a new set of outside holes in the 3.9 heads for the 4.0 intake to bolt to. The intake runners line up perfectly. It's just the 4 outside bolt holes. The center hole is out of line too but I can drill a hole in the intake to take care of that. Or just leave it out completely. Deffinatly going to need new intake gadgets though, just in case. The 4.0 has the individual rubber gaskets. The 3.9 has the single metal gasket.



I'm not really concerned with the missing idler pulling on the 3.9. As long as the belt doesn't hit anything it should be fine. I don't think the newer 4.2 has the extra pulley either but not 100% sure. Still something to keep in mind though

 

The 3.9 ls block (from 2005 iirc) is based on the 4.2 block from Jaguar, hence the intake difference. The 4.2 has also a different front cover, and a different size hole for the main pulley, so you may need to play which setup of pulleys you are going to do, but I think the 4.0 cover you have will fit as well, so you can reuse all your 4.0 pulleys. I think the 4.0 block as a coolant connection on the rh rear for the tb/egr, and the 4.2 not, but its to long ago I played with these blocks. All in all you should be able to make it workable.

 

For those who may be pulling there engine here's a small tip. Remove the intake first. Why? Because here's the top bell housing bolts. The top 2 holes didn't have a bolt in it. Not sure if its suppose to or not but mine didn't.



I got the new holes drilled and tapped and the intake. I set the 4.0 intake on the 3.9 and bolted it down with the center bolts and used a center punch just big enough to fit in the hole to make sure it was centered up.

An 8mm tap, letter H drill bit (you can get them as a pair) along with a chamfer bit (optional but it gives a nice bevel to the help guide the bolt in) and a can of lubricant. I'm not going to go into drilling and tapping. Theres quite a few Youtube videos if you need help.

I wrapped the bit in tape to make sure I got the right depth.



Theres a few different ways to make sure you get the hole straight in. The proper way would be to drill a hole in a block, clamp the block to the engine and use it for a guide. I was feeling brave so I leveled the surface with a level and used the bubble level on my drill to keep it straight up and down.

Make sure you put something in all the intake hole so nothing gets in. This is a given but just wanted to point it out.



You can see how far I had to go for the new bolt hole



Theres a coolant line on the 4.0 and the 3.9 that routes through the throttle body. This is common feature. The idea is for cold climates to help warm up the throttle body and keep ice from forming. The connector on the 4.0 is larger than the 3.9 but the lines are the same size. This is just plumbing and I'm going to cut the line off just behind the reducer and put a coupling in to lengthen the line to connect to the 3.9 nipple on the back side of the thermostat housing.



Also I had to swap the cam sensors. This is after the swap. The 3.9 was pointing to the back.



On a side note, if you ever change the valve cover gaskets make sure get the correct bolt in the right spot. The back, top bolt is shorter than the rest to account for the cam sensor. I was going to use the sensors from the 4.0 but this is what I found when I took them out. It wasn't throwing any codes and ran fine but its something to note.



I'm still deciding on what to do with the center intake bolt. I may just leave it out. This isn't a race car and with new gaskets and maybe a little RTV gasket maker on the center gaskets it may be ok.