It's not easy on this
engine. The drain
plug for the block is actually behind the starter. You cannot get to it without removing the starter. Crazy, I know. I didn't believe it myself until my
mechanic showed me another W46 on the bench and I could look for myself. Pulling the starter does not necessarily have to be a big job, but it will definitly add time to the job.
Maine Sail once wrote a post of how he flushes an
engine using an external
electric pump and some appropriately rigged-up hoses. It involves removing the thermostat as well. If you pull the starter to drain the block, and use his
flushing method, you will get the job done and well. But what a pain