In Reply to: CAT Bad? removing cat completely? AND COOLANT LOSS posted by Help(LONG!!!) on January 29, 2001 at 18:44:52:
Since nobody answered your question, I'll give it a shot. For your varying idle, check your idle position switch. You should hear it click when your throttle butterfly is moved slightly off idle. If that is set correctly, replace your idle control valve with one known to be good.
For the cat, take it to an exhaust shop and see if it can be welded. They usually can be repaired a few times before you can scrap them.
The CC has a honeycomb structure inside with a chemical catalysist that turns bad polution into good polution :-) When you "broom handle" your cat, you are essentially breaking the honeycomb and getting it out of there. This is fine if you are in a state that doesn't require cats or emission testing. You will probably fail the emission test if you don't have a working cat.
I have never altered the cat on a bmw, so i don't have any info for you regarding noise or performance.
If you had a heater core leak, you would know. The interior of the car would smell sweet and the windows would fog up when you used the heat.
If you are loosing coolant, it may be escaping through hose leaks under high pressure and evaporating on the hot engine. Check for teltale white scaley stuff around the hose ends where it looks like water leaked out. Also you could have a cracked block. But check for leaky hoses first. Pressurize the cooling system with a cooling system pump and check for burbly (is that a word?) leaks.
Engine light? Which one?