Disco 4 (LR4) Diesel inlet manifold

Hi chaps,

For those that remember my friend has a Disco LR4 (the diesel 8 speed one from 2012) and we had a list of weird faults that in the end turned out to be a cracked inlet manifold. Thread here:

https://www.landyzone.co.uk/land-rover/3-fault-codes.321721/#post-4098297

The manifold was replaced with a genuine Land Rover one and all was for 8 months or so and then bang! Lots of the faults mysteriously reappear. Short story is that after a smoke test it appears the same damn inlet manifold has cracked again.

So the question: what could possibly cause the inlet manifold to crack again? Surely there cannot be that much pressure? Could it be differential heating and cooling?

To be fair to Land Rover they've offered to look at the car and because it was a genuine Land Rover part bought from them they're willing to replace it free of charge if the part was faulty. But for me the question remains: why are these things cracking? Talking to a jaguar mechanic and he said they used to fail all the time on the Jags with the same engine too! So what design flaw have JLR introduced?

Know JLR are aware of this and found the TSB

But indeed as u say doesn’t explain why , will do some digging to see if there’s an answer

https://www.disco3.co.uk/gallery/albums/userpics/22994/LTB00768v2.doc

Good to hear that the repair is being honoured FOC

Just found this on the D4 forum

Cracks are due to a manufacturing defect.
"Cause: Material thickness and fillet radius of the valve cover not to specification"

New strengthened part numbers I beleive.
LR073585 Left valve cover
LR074623 Right valve cover

Is it made of plastic?

johnlad said:

Is it made of plastic?

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I think it is mate , but not 100%

gstuart said:

I think it is mate , but not 100%

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Probably why so many fail

johnlad said:

Probably why so many fail

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Indeed, seems the modified ones are now made of a thicker material

Reading some threads it looks like a very involved job to replace them

gstuart said:

Indeed, seems the modified ones are now made of a thicker material

Reading some threads it looks like a very involved job to replace them

Click to expand...

It is a total FPITA.

Have you checked the boost pressure when under load?

lynall said:

Have you checked the boost pressure when under load?

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It all looks normal. I've had my Torque app connected via my ODB2 thingy and I've got the 4Dcan software from Storey Wilson as well. Nothing is showing as untoward except when those fault codes show up. To be fair the codes only come up when you floor it and give it some beans.