Heater Hose
One day, I pulled I came home from work and pulled into the driveway. I turned the engine off and got out to go inside. I immediately noticed smoke pouring from the engine compartment. Visions of multi-thousand dollar repair bills started dancing in my head as I carefully opened the hood. I was mildly relieved when flames were not ungulfing the engine. I then caught the unmistakable odor of burning coolant. I poked around the engine compartment to see if I could spot the leak. For those of you who don't own V12's, there is not alot of room to see anything so this was harder than it sounds. There was only leakage on the driver's side so I was able to pinpoint the leak to a blown heater hose. I was somewhat relieved since a new hose shouldn't cost that much (although leave it up to BMW to charge $100 for a rubber hose).
The heater valve has three hoses in it, two to the heater core and one to the engine block. I was this last one that was the problem (thankfully as you will find out later). Since I could see both ends of the hose, I tried to replace it without taking anything apart. This attempt quickly failed.
I figured I had to remove the heater valve to get more room. This is easier said than done. The valve lies under a bracket that supports the positive battery lug and some wiring. This bracket is attached to a larger one that houses 3 diagnostic plugs. By the way, the Bently manual doesn't mention anything about any of this!
First remove the cover from the heater valve. It pops off, but requires so much force I was sure I was going to break it. This will expose the heater valve and its mounting nuts. Go ahead the remove the nuts now and see how impossible it is to remove the valve, keeping in mind it has the auxillary water pump attached to it!
Next, remove the diagnotisc plug bracket. It is attached by two bolts. One is an odd plastic nut. I stripped mine pretty bad taking it off. I have no earthly idea why they would use this kind of fastener here. The second nut is near the positive terminal. You will have to remove the terminal's side cover. This requires a fair amount of force, I used a screwdriver to help it along (kind of like removing a cake from a cake pan) thinking I was about to break it (this seems to happen a lot). With that bracket removed, you can now move the wiring out of the way a bit. I also removed the wiring harness bracket on the heater valve bracket so I could move the hose.
You should now remove the hoses going into the heater valve and the one going to the aux. pump. They should be fairly easy to remove since you have some freedom of movement. You don't need to remove the short hose that connects the valve to the aux. pump. Be carefull you don't drop a hose clamp. You might also want to mark the hoses before removing them.
Now, removing the valve is just a matter of working around all the wires, metal and hoses to get it out. It helped me to move it towards the engine a bit and back it out.
Now I just yanked the faulty hose out and put the new one in.
