Hi
I am trying to buy a 2002 discovery's 4.6l with secondary air to put in my 2004 discovery with 4.6l secondary air. The junk yard guy says you cant use a 2002 in a 2004. I think he is wrong. Please help. This engine is in great shape and low miles so i dont want to miss out, but i cant afford to have a problem either.
Thanks!

 

Did the junk yard guy clarify the 2002 model year comes with the 4.0L engine and not the 4.6L engine?

 

It will bolt straight in as long as it has secondary air. If it doesn't you have have your original heads decked and bolt them onto the junk yard engine. You will, however, have less power because the 2002 had a 4.0 instead of a 4.6 (as already mentioned).

What are you switching the engines for? Have the head gaskets on the junk yard engine been done yet?

 

4.0 vs 4.6 would make sense as to why he said it wouldn't fit.
parts people just repeat what the computer tells them,
according to the computer they are to different engine.

But as stated a 4.0 will bolt into place of a 4.6.

 

It's a 2002, but it's a 4.6l. The catalyst sticker in the front of the engine compartment says 4.6l.

 

The 2004 engine is a replacement that the po had put in around 75k and I'm just short of 200 now. Also the heads have been done several times in my engine because the head bolt threads keep coming out. I think it's because the po ran it while overheating. Also I am missing a camshaft bearing and have low oil pressure because of it.
This engine is toast and would cost more to keep running than the 2002 4.6 with 86k would cost me. I don't think the 2002 engine has been done yet and I am considering doing heads etc before putting it in, but might also just drop it in and run it until it needs it.

 

Ok, that makes sense. Again though, the 2002 is not a 4.6. It's a 4.0.

It will bolt straight in and you'll lose a little horsepower, but as far as reliability is concerned you'll get a little increase and it's definitely nice to have so many fewer miles.

If I were you, I'd do heads, oil pump, and timing chain while it was out of the truck. Might even throw a cam in it if you have the money and take a die grinder to the intake and Exhaust ports for a port and polish. Do a little research on that first, but it makes a noticable difference. they sell port and polish kits on the Web wIth the attachments you need. that will gain you back some tof he power you lose from decreasing your displacement.

 

I'm going to have to look into that. I saw the sticker that said 4.6l, but other than Wikipedia I can't find anything that says there is a 4.6 available in 2002 discovery.

 

Yep. There were no 2002s made with the 4.6. The only way that it's a 4.6 engine is if the previous owner swapped in a 4.6 from an 03-04 or atleast swapped the rotating assembly, which would mean the mileage reading would be incorrect.

Is it possible that the truck is an 03 model year made in late 02? That what mine is. It would have the face-lifted front end if that's the case, but the door sticker would have a 2002 production date.

 

no 2002 4.6 the junkyard is most likely going by the VIN., not the emissions sticker