Are 4.6 Range Rover engines direct, bolt-in replacements for any DII engine (acknowledging the need for a 4.6 DII ECU for the '99-'02 model years)?

 

Yes, except for a few things. I believe the flex plate spacer at the back is different and maybe one of the accessory brackets. But essentially the same thing. You can use a 4.0 ECU with a 4.6 motor and a 4.6 ECU with a 4.0 motor.

 

Was the Range Rover 4.6 manufactured on a completely different line? It has to either be a different block, or it was tooled/bored/etc on a completely different line of equipment, right?


Could it be that the RR and D2 are the same block cut from the same tools, but the RR always ran cooler? Were they rolled-out on DexCool as well?


Now I know to look for a RR 4.6 if my D2 4.6 ever gives up.

 

The casting of the blocks was not a precise process. In 97' Land Rover started using a technique(can't remember if it was sonar, X rays, or?) to measure the thickness of the block walls.

The thickest walled blocks were designated "red" blocks and given a red paint dab on the outer cylinder at the valley, I believe it was number 3. "Reds" we're always used for 4.6 engines. The next best blocks were "yellows", if they ran out of "reds", "yellows" we're used on 4.6. The worst blocks were "blue" and used for 4.0 motors.

There are paint dabs all over these blocks but this dab was always on an outer cylinder in the valley. I actually tore down a 2001 4.6 that I could clearly see the red dab on. I posted a photo on here a couple of years back. The motor went because the owner put the wrong oil in it.

 

That's the 2nd-most useful bit of info that I have learned here. Where did your source come from on this? Are there any more relative tidbits that you are aware of?

 

I think the RR P38 had way better brakes than the Disco II also. The 4.6 feels underpowered in the RR, but okay in the Disco. So I would get the 4.6 from the RR and put it in the Disco and have the best of both worlds.

 

A book

https://landroverforums.com/forum/di...s-57841/page2/

I have it somewhere but have not looked at it for over a year

 

Thanks for sharing that. I find a great deal of interest in these trivials. Is this the red dab of paint that you were referring too? Will you send that book to me the next time I order some parts?

 

Slightly different location, but that seems to be it.

The book is crazy expensive.

 

Here is the page on block grading. Not sure if the resolution is good enough to read.