740d - 2018 - inlet manifold - decoking/walnut blasting?

[turboman786]

My 2018 740d has reduced power recently - car is under extended BMW warranty

Cars been diagnosed as needing a new inlet manifold, all covered by warranty

BUT

Advisor states that car will need walnut blasting /de coking (this is before theyve even opened the engine up )

My question is

- are the two issues linked?..decoke and inlet manifold

- BMW say the decoke isnt covered by warranty and they will charge £1k inc vat which sounds like a lot for a job that they dont even know that the car actually needs

- they say they are happy to change the inlet manifold without decoking subject to me signing a disclaimer (Im not sure what Id be disclaiming !)

The 740d is my longterm work car and has been superb in my 2.5 yr ownership...I planned to keep for another year

So ...decoke or leave it ?

[bigdom]

I'm not sure how the two things are linked, unless they are stating an increase in pressure has split the manifold? I've had a manifold replaced, and that was never mentioned.

As far as i'm aware, the coking issue is common on 'N' series, by the 'B' series they had resolved the problem.

£1k is exorbitant. I think it's about a £400 job normally, and they've already had to take the inlet manifold off for the warranty repair.

If you don't use Premium diesel, stick something like Archoil ar6900-d max in, I've always found it's keep mine spotless.