I had been trying hard to remove valve covers on my 92 400E for the whole day, I managed to remove the left valve cover, but couldn't remove the right one. The problem is the outside bolt at rear, there is little space between valve cover and the firewall, I can't apply any torque to the bolt with Allen wrench.

Do I need a special tool? or I have to remove the firewall? I am now still trying in my garage, helps over the internet will be greatly appreciated.

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99 BMW 540i 6-speed 110K Km
03 SAAB 9-5 wagon 80K Km
92 400E (Sold) 245K km
Still missing the days with the Benz, it kept me busy.