Hi,

1992 535i 5sp. 146,000 well care for miles. Never overheated in my ownership, waterpump,radiator fine. Drove it home Friday last and Saturday morning came out to the garage to find coolant underneath (couple of quarts).
So I leave it alone until yesterday to troubleshoot problem.
a)
I find the overflow tank is empty (that explains the 2 quarts on the floor)
b)
I start the car and don't see any obvious leaks or hear any unusual noises.(only ran for 2-3 minutes)

So, since my wife has complained about the weak heat in the car lately I decide I probably need a new heater valve or aux water pump.
I take them out to find nothing wrong with either one as far as I can tell. The heater valves energize as they should and I can hear the pistons rise and drop as they should. I took it apart to verify nothing broken on the inside and no apparent leak on the outside like a crack or something.
The aux. water pump also will run when connected to 12volts and no strange noises or cracks in it either.
The hoses I removed at one end all look ok. So not any obvious broken hoses or splits etc.
Any ideas for my next steps? I would appreciate the assistance. I can't say that in my 26 years of BMW maintanence I have ever seen a car throw-up it's coolant without being hot or overheated.
Thanks in advance for any assistance or suggestions.

Scott