Hey guys, did all (US) '03 D2's have the 4.6, or did some have 4.0's? I just picked up a parts truck and don't know what I have. The vin is: SALTY16443A776838 Thx!

 

Yep. All 4.6 unfortunately.

 

All 4.6L unless the previous owner was smart and slapped in a 4.0L.

 

So what if any, are the pitfalls of rebuilding the 4.6, even if I have to sleeve it?

 

Excessive pressure being a 4.6 could crack the block, that's my experience. I've gone through 3 4.6 blocks so far, all of my 4.0, 3.9, and 3.5 blocks have been perfect.

 

I bought a junkyard 2003 with a blown motor. Pulled it. It had been rebuilt previously. Already had the larger "B" pistons in it.

I rebuilt it again. Put in new bearings and a performance cam. Used ARP studs and the all-metal Cometic head gaskets.

It's fantastic! Cost me just under $2k for my parts and machining. Labor was free because... me!

Highly recommend using the Crower cam in the 4.6.

 

Thats encouraging! Thx ND! About how many miles on your rebuild? No liners?

 

Isn't the block the same for 4 and 4.6? Just the crank and pistons/rods are different. 4.6 blocks could be lower quality though, with thinner water jacket walls, as they were near end of production.

 

That's how I understand it from what I've read. And the P38's got the best blocks..

 

No liner issues or top-hats.

When I pulled the heads I examined the cylinder sleeve tops and there was caked on carbon which suggested to me that the sleeves had never slipped (I would have expected a crack/line if the cylinder liners were moving/slipping).

To me, this is not a big deal because if later you ever do have cylinder sleeves slip, then you can pin them with the motor in the Disco without any disassembly (or you can do a fantastic, easy pin by simply removing the heads).


My daughter has put more than 4,000 miles on my rebuilt 4.6 so far. Burns/leaks 1/2 quart of oil every 500 miles.

Trivial. She uses 10W40.


If you are concerned about the block then pressure test it. That will let you know if it has cracks. No point in rebuilding a cracked block. It's not going to get better!

If it pressure tests ok then get your flat edge and slide your cheap feeler gauges underneath your flat edge in various strategic locations such as your Main bearing journals, cam journals, and top of block (under where your heads sit) after you've removed your crank and cam.

If they are straight then it seems safe to rebuild, assuming the cylinder liners aren't horribly out of round.

Let your machine shop grind your crank and deck your heads. Use oversize bearings as appropriate.


I'm won over to the all-metal Cometic head gaskets because really... how the heck can all-metal head gaskets ever blow?! You are removing a weak point.

Same for ARP Studs+nuts instead of Rover stretch head bolts.

Put in a performance cam. This is your one chance to make basically the *only* real performance improvement to your 4.6.

Install a new timing chain and new oil pump+cover.

Done.

That just leaves one weak point in the whole Rover system: the thermostat... (and there are solutions for that if you like).