Ok I'll borrow my friends socket. He bought one from the dealer, hopefully the S320 uses the same cap as the S600. Knowing MB it probably does.

Now how is the brake system different then a W126's with ABS? I was going to try and bleed them the traditional way. Ie having one person on the bleed screw and another pumping the pedal. I have done this for years on my W126 with great success. Some people claim it could causes the master cylinder to leak down. The way I look at it if pumping the pedal causes the master cylinder to leak it needed to be changed anyway.

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2006 CL500
2009 C300 4matic
1969 280SE
2023 Ram 1500
2007 Tiara 3200