August Update:
I managed to made good progress on the E55 in the last few weeks, here's the latest jobs completed:
Replacement valve covers arrived so I was able to continue with the new gaskets. I noticed the left hand gasket was rubbing against the bolt and wearing thin. I'm going to change the oil and filter shortly once there's no leaks.
I ended up painting the covers in a satin black which turned out ok, not my best spraying but ok for how visible they are. They're a pain to prep for paint, I would probably leave them alone if I was to do this again.
Unbelievably the replacement valve covers I ordered ended up being damaged with the courier but I managed to make one good cover out of two. They definitely clean up the engine bay and make it look a little smarter.
£50 in total (£40 for gaskets, £10 paint etc)
Brakes Pipes & Hoses
Next up was the brakes! I knew this was going to be one of the more painful jobs but it was even worst than I thought. The pipes were 80% good however in places very bad and I didn't fancy putting any pressure on them. They are so well covered by plastic the tester obviously couldn't see them so didn't pick up on it. I would definitely advise anyone with a w211 to take a look behind the covers and not rely on your test!
I bought new hoses all round as it made sense when all was apart. I could have got away with just replacing the rear lines however opted to do all front to back. The biggest issue was getting the bleeders out of the calipers, completely welded seized into the calipers. After many hours all came out apart from the rear left caliper, it broke and had to be drilled and repaired. The actual pipes were quite easy to replace, they just run along the inside of the cill and don't go over the fuel tank. There's also a surprising amount of space around of the V8 lump. There's no noticeable difference with the new hoses or fluid but it's reassuring to know the pipe is not going to burst! In total this
cost £125 (£30 on copper pipe, £70 on hoses, bleed repair kit, fluid, ends & nuts)
No Leaks
Managed to get the tank sealed (left hand side was always dry) so there's no more petrol smell inside. I would like to replace the connector at some stage.
I find this rust remover works very well, I've used it quite a few times on this!
Ready for the road!
That's all the jobs that I wanted to complete before starting to use the car, lots more to do but I plan to enjoy it for the next few weeks! Overall I'm still very happy with the purchase, for 230k miles I think it's now in good shape.
Thanks for looking.