Help - e53 Knocking from transmission - VIDEO

[SMOKEY53]

Update time. Wanted to close this out because I find it so damn frustrating when I'm trying to research things on forums when someone starts a thread, asks for and accepts all the help in the world - and then never posts the outcome. So.

Had the injector seals replaced, new clamping cradle (not a technical term) fitted to hold the injector down, EGR cleaned, PCV replaced and fuel filter replaced. New manifold gaskets and seals etc. Mechanic figured out that the person who replaced the rocker cover gasket (which coincidentally happened immediately before I took delivery of the car as it was picked up during PPI and I demanded it be fixed) must have levered against the injector - in the process bending the stud attached injector - thus allowing the compression leak. Unbelievable. Picked the car up this morning and it's a lot quieter and idles smoothly.

So obviously the sound of that compression leaking out past the injector was the cause of the fearful knock.

Mechanic has suggested that the injector is still bad, that the backflow test shows that and that the car will be down on power and using more fuel. But considering the backflow test was conducted before the injector was sealed (and not again after) I don't know......

I could get in there again and replace the injector for peace of mind, but if the car is running fine and not throwing any codes, it might just be labour in vain. Will keep an ever watchful eye on it.

Can upload a video of the backflow test for anyone interested, otherwise - consider this chapter of the nightmare is over! For now.

Thanks for all your help!