Due to a leaking exhaust valve of my 400i VIN48739, I had the left bank cylinder head overhauled in a specialised engine shop. while the engine stayed in the car, I noticed when removing the head: firstly extremely tightened nuts. It was definitely much above the 100Nm specified in the manual. Secondly the old gasket was sticking to the engine block due to use of some sealing compound, which is basically a no-go. After reassembly of the engine with the correct torque applied to all the nuts and bolts, I experienced a tremendous leak of cooling water into the oil sump (fortunately before starting the engine!). A detailed investigation showed a major leak into the rearmost oil drain channel between cyl. 8 and 9 to the sump. Now it is obviously not possible to do any correction on the sealing surface of the block and I can not imagine any other remedy than applying again some kind of sealing paste between the block and the gasket. Is there any experience in the community with this kind of problem? Any suggestion about suitable sealing paste? This should of course not dry too quickly since it may take more than an hour to get it properly applied and get the head fixed and tightened to the engine. I'd very much appreciate to hear about such kind of experience because I'm quite desperate now.