Picked up a M30B35 engine for the BMW yesterday. Started easy and sounded healthy before it was pulled from the donor car, but the nasty coolant that was sitting in that engine for who-knows-how-long has left a fair amount of chalky, scaly mess in the coolant passages.
Anyone have a good way I can somewhat easily clean or flush out some of that nastiness without having to put the engine in the car or run it? I also don't want to strip it down to the block just to clean out old, nasty coolant....
Plug all the ports for the cooling system. (Radiator hoses, heater hoses, etc)
Add vinegar from highest point until full
Let sit for a minute (couple of days)
Flush thoroughly with water
This is spitballing. Never tried it.
You could always convert to Evans coolant and use their prep fluid....
Yeah, the irony is that I know all kinds of ways to get this done IN the car. Problem is, I just installed a new heater core and radiator and don't want to push all the flushed junk through those brand new components :/
My idea would do that, however im not sure of the vinegar. I know it eats lots of deposits and rust. Should be able to do it with a couple of wooden plugs and hose clamps.
I've used vinegar before with decent results. Usually trying to clean dex sludge out of heater cores. I flush with the hose until I can't take it anymore. Then I try to drain as much water out as I can and then prop the two hoses up and fill with straight vinegar. Let sit as long as you can and then flush with water. Repeat until you lose interest. I've also run 50/50 water/vinegar instead of coolant for a few weeks/months. Seems to work decently, but the dex rust color never goes away.
CLR mixed with water and let it sit if its a steel block has worked for me. Aluminum I would not risk it.
I have use CLR on aluminum with out issue. Then again I also have never read the directions on CLR to know if it is a problem. 
Lost of people sweat by CLR or Lime-a-way
