I just purchased a 2003 Disco II SE with 69k miles. Vehicle was within the VIN range of the problem oil pump vehicles and owner had it fail and had to perform a full engine rebuild. He didnt seem the most knowledgable on car lingo but said he had liner problems in his 4.6 block so he had 4.6 internals put into a 4.0 block and new oil pump does this sound right?

I paid $7500 just dont want to get screwed. Vehicle is showroom quality clean, and drives like a top just worried and want to make sure theres no problems down road. Compared to others in my area for 5k with over 100k miles didnt thing I did so bad. I figured with him already going thru this repair less then 10k miles ago it was a good buy. Any insight would help as Im new to the vehicle? Please throw any comments at me

 

4.0 and 4.6 are the same block, there are just a lot more 4.0 out there so they are cheaper. Sounds like his 4.6 went bad and he got a used block and had it built with his old parts. I wonder what new stuff went in with it... I'd hope at least rings and bearing. Maybe a cam and lifters would be nice too. Does he have receipts for the work?

 

He has all records from day 1 of ownership. I pick them up Saturday cause they were at his office. Then we will see the parts list. Legitimate guy in our community so I feel ok. I think your right he might have used a 4.0 block after liner went in the 4.6, he probably did block, bearings, oil pump, rings, etc or so we hope. Was there no way to avoid another liner issue in rebuilding? Or has this problem been rectified in better liners of way of rebuilding? Or will I be looking at another rebuild in 75-100k miles

thanks

 

If everything was done correct, your engine should live a long, healthy life. The 4.6, for some reason, seem to suffer from liner problems much more than 4.0's. And oil pumps. The 4.0 in my '98 has 180k+ and never has had to be opened since i got it( 4 yrs and 70k miles)

 

I did not know that the 4.0 and 4.6 were the same block.
Where does the .6 liter come from?

Is the stroke of the piston longer? That would imply a wider crank shaft.

Or, is the cylinder just honed out and a wider sleeve put in?

This would tell me-
that the blocks may be born the same when they are cast
But -
Machining and different sleeves make them different.

Somehow - the 4.6 gets the extra .6 liter.

From Wikipedia:

The 3948 cc V8 petrol version from the Disco 1 was replaced with the Range Rover P38 Thor 4.0 litre Rover derived V8. There was no actual increase in capacity over the previous 3.9 L engine. Although the basic design of the engine was similar it was actually quite different internally. It used a different crankshaft, had larger bearing journals with cross bolted caps and different con rods and pistons. The blocks were machined differently to accept extra sensors for the Gems and Bosch (thor) injection system and to allow the extra stroke of the 4.6 crankshaft. For the 2003 and 2004 model year Discovery II they changed to the 4.6 L V8. ACE (Active Cornering Enhancement, an electronically controlled hydraulic anti-roll bar system) was fitted to some versions, which reduced cornering roll. Self-levelling air springs were fitted to some models and European type-approval for seven-seat vehicles was only given for air-sprung cars.

Wow, here are some guys who KNOW it..

Not true! I have been running 4.6 crank with 4.6 rods and 4.0 pistons for multiple years and over 40,000 miles with my 96 GEMs Disco without a chip or anything special. The compression ratio goes up to about 10.9 :1 which is right on the edge of the limit for premium 93 octane gas. The knock sensors with this set-up will retard the timing 4 degrees more than a stock 4.6 (at least on my engine). The fuel mixture is still on the rich side - no need for bigger injectors AND no worries about burning pistons for a lean mixture. Nothing hits anything - the only issue is the high compression and slight timing retard that the GEMs will do to prevent pinging. If you rewrite the 4.0 GEMs chip to put a 4.6 GEMs code (Range Rover Code) on a Disco you will set the check engine light for the electronic transmission code. Mark Davis has a chip that will fix this but it simply too much money when the 4.0 chip runs as good as it does. The GEMs computer in my truck had adjusted well I only have issue with poor grade gas or old gas but that is not very often. I like this engine set-up and I know one other person running it (he has a chip but not sure I can tell the difference verses mine) and I know of several others building similar set-ups. It is the cheapest way to get some extra power out of a 4.6 IMO

In 2006 when my 3.9 lost a liner I used:

Engine Supply
304 East Dyer Road
Santa Ana, California 92707
714-556-0310

They did the following;
- machined the block, and installed the flanged "top hat" cylinder liners, including bore and hone
- "decked" and "line bored" the block after liner installation
- installed camshaft bearings
- evaluated the pistons for reuse, and they were found acceptable
- pressure tested the cylinder heads
- polished the crankshaft
- sourced the piston rings, all the bearings, including new camshaft bearings, lifters, timing chain,
composite head gasket

Approximately $1,400.00 parts, and $ 900.00 in labor, back in 2006.

I had to purchase new cylinder head bolts and a new Crower camshaft from D&D.

I also replaced all the cooling hoses, fan belt, and fan clutch.

I have put 40,00 miles on this engine since the rebuild and no problems..

 

The blocks are the same. Longer stroke in the 4.6L. No difference in machining required for a longer stroke.

 

Thanks everyone for the insight. Think I figured out my answer after talking to owner some more.