also they abandoned the grading process with the 03/04 discos because that was the only vehicle that was Getting those motors and it was the end of the production cycle. It has been said that they even used rejected blocks that were on the shelf.

thst is why 4.0 Disco's and 4.0/4.6 range rovers have less problems.

 

Yes indeed abran, thanks for the reminder. So if the OP has an early 4.0 he could take some common sense steps and swap this engine with an expectation of very good results on a low budget. Best advice IMO.

 

I haven't read that in the literature you posted. Unless I just haven't read far enough, the case appears to be that as long as the engine is a genuine Land Rover unit, none of the 4.6 engines used anything less than a yellow block, and then only if they ran out of red. This was until the end of the run in 2004.

 

What abran discusses is more along the lines of 'inside baseball' and I'm not sure that is even discussed in the literature. Also realize that some of the pages in the literature are obfuscated when using the link provided.

 

Interesting. That's an assertion that I would like to see confirmed in some way, I.e. taking several known original Rover blocks from 2003-2004 U.S. discos and checking the valleys for color marks. I would think that, if they were indeed just throwing whatever came out of the foundry into their vehicles, they wouldn't have bothered with the testing and marking as is reported in that literature.

I would be more inclined to believe that there a mostly yellow coded 4.6's floating around rather than red, but to have every 03-04 engine get a blue or worse rating seems unlikely, even for a company in dire straits like Rover was.

 

Is there a comprehensive writeup on the rover "knock"? I ask because i did extensive research months ago before replacing my head gaskets and came across this article JE Robison Service - Bosch Car Service Specialists ? the blog: The last word on Land Rover liner failures - I hope! , among others, that explained the block failures and causes of the knock.

According to this, and other sources, it would seem that the 4.6 is incapable of "slipping" liners. The block can crack and result in an overheat/coolant loss situation, but the liners cant physically move.

but then i also seem to remember a writeup that insinuated that LR failed to seat all of their liners properly, resulting in the slip phenomena despite a block design that would otherwise prevent this.

 

There's a lot of information on this but suffice to say the Rover friction fit liners can definitely slip. What happens (quickly) is (1) hairline cracks in the water jacket can form which causes coolant to leak behind the liners. This 'lubricates' the liners from behind, and with the pistons moving up and down causes the liners to unseat and slip causing ticking. Sometimes even without a coolant leak behind the liner they come loose due to overheating, in many cases due to oil pump failures which the later 4.6 engines have become famous for. As an aside I also believe the rearmost cam bearing can get loud and make a sort-of ticking noise. The oiling system of the valvetrain is also dated and inadequate in my view, so rocker, lifter and pushrod noises are also common and can be called 'ticks.'

 

Yes I understand that the blocks Crack, and this is generally the cause of slipped liners, but the info on this is very sketchy. And by that, I mean the the data points are all over the place.

For instance, that forum post and subsequent video "proving" that 4.6 liners slip at normal operating Temps. The guy probably didn't confirm that the engine was a genuine Rover unit, only that it "appeared" to have ever been apart. It could have very well been an early crate motor that replaced an oil pump failure unit.

 

They were still replacing 4.6's in the failed 03/04's with those "crate" blocks up through 2008 when warranties started to end.

 

The blocks used for replacement were Coscast blocks. A company that was hired to fix their block issues for the warranty replacements.

When you think about it, during their casting process they ended up with 3 grades of blocks. Red, Yellow, and Blue. Red was for 4.6 motors that went into RR. Blue for 4.0 and yellow was used for either when the prescribed one was not available.

Keep in mind, the grading was based on the random output of the casting process, they could not necessarily control the process, it gave them what they got.

In 2002 14,095 D2s with 4.0 motors came into the US. Same year 3,927 Range Rover P38s were imported. Some SE and Some HSE, but I do not have the breakdown. For arguments sake, lets say all were HSE, hence all were 4.6.

We can then make the deduction that 78% of the blocks used were Lower quality. Granted, I'm taking some liberties with my theory and numbers.

Do you think once 03/04 production came when they no longer were putting these motors in Range rovers, meaning they were only making 4.6 motors not 4.0(which was the lesser of the production numbers) that they discarded 78% of the blocks and only used the red ones for the full production numbers?

To me it makes perfect sense. Also, I have bought and sold many Discos and can say hands down that I have seen more failed 03/04 disco motors than anything else. Thats why it is advised to buy a P38 4.6 for rebuild.

But hey, I am just a monkey with a wrench...