heater core (heat exchanger) questions

[Cobra Jet]

For those of you who have replaced or R&R'd a heater core (also commonly referred to as the heat exhanger) in an E30 BMW - is there a complete tech process for this online somewhere (w/ pics)?

Also - where is the best source to buy a new heater core? Is replacing the heater control valve (also known as the "water valve") always necessary as well, or does this part only get replaced if it is damaged or non-functional? How do you tell if the heater valve is bad?


Would any of you replace a bad heater core w/ a good USED, non-leaking unit (price varies, but say from $20-$40), as opposed to buying a brand new unit that is in excess of $100+ (from most online vendors)?


Thx.

[twright]

I bought a used heater core for my 318is. It worked great. The guy I bought it from (Reggie'sMotorWorks.com) said that the heater cores are pretty durable and didn't think that a used one would cause any problems.

[Uber E30]

http://r3vlimited.com/board/showthread.php?t=98782

[Tbolt]

I recently had to replace my heatercore and valve. I used the guide uber e30 mentioned. Make sure you replace the orings!