what's going on here?

[[1990]525]

Someone did this, and I don't know why... Any clues? :P

noticed this
http://i.imgur.com/ioEaE.jpg

its #4 on this diagram
http://realoem.com/bmw/showparts.do?model=HC23&mospid=47402&btnr=13_0291&hg=13&fg=15&hl=4

found this
http://i.imgur.com/cDgkI.jpg

goes from water pump to block
http://i.imgur.com/cQ1UV.jpg
http://i.imgur.com/BLWLO.jpg


what does that #4 plate thing do... and why was this bypass made? :O

[Mr._Graybeard]

There's a coolant loop in the M20 throttle body that warms the intake up to prevent icing in cold weather, but the loop can leak with age and metal erosion. Somebody bypassed that loop on this engine, probably to bypass a leak.

[[1990]525]

There's a coolant loop in the M20 throttle body that warms the intake up to prevent icing in cold weather, but the loop can leak with age and metal erosion. Somebody bypassed that loop on this engine, probably to bypass a leak.
Would this cause excessive condensation? Should I bother to refit it?

[Mr._Graybeard]

Well, BMW put it there for a reason. If you live in an area where it never gets cold or damp, you might get by.

If it were my car, I'd fix it, but I live in an area that gets cold and damp. It could be just a failed gasket, I believe. It's not an uncommon problem -- if you google leaking M20 throttle body you'll get a lot of hits.