BMW: waterpump gasket replacement, corosion, brown tint

Question
i have an 84 alpina c1 2.3.on the way home from work i stopped
at a traffic signal and noticed a little steam coming out from
under the the right side of the car. noticeable only when i
stopped. it was at night and iwas only a mile or so from home. a
block away istart getting a knocking sound. next day  trace the
lek to a hole in the gasket near the bottm. i figure replace the
gasket, the shop says that plus the wpump,
radiator,thermostat,,all hoses,and maybe the heater core, reason
being the water had atint of brown and that the oxidation could
clog up somewhere causing it to overheat and warp the heads. i
drove 120km on the higway before i could get to him and it ran
at normal operating temps.i guess my question is what would
you suggest and can i do all the work myself ? thank you for
your time, michael.

Answer
Micheal,
 I think the shop is trying to take your money.  It's not unusual for coolant to have a brown tint, especially when it's not been replaced in several years.

 All you need to replace is the waterpump and gaskets.  While I was in there, I would replace the timing belt and tensioner as well.  It's not a "hard" job, but it's just time consuming.  Since you have to pull all the covers off the front of the engine, you should replace the timing belt while you are in there, so it will save you a big headache down the road.

 I would not replace the radiator, hoses, heater-core or anything.  I WOULD give everything a nice flush to get as much old coolant out as possible.

 Also, when you replace coolant, and you mix it with water... make sure to use DEIONIZED WATER, this will prevent any corosion due to water being in the system.  It may be overkill, but it will help prevent any of the BROWN tinted coolant from appearing.  You should be able to find it in grocery stores in the bottled water section.

 Hope this helps,
 Josh