[rebidus]

Driving 300 miles home the other night, I turned off the A/C for a bit, and the windshield fogged heavily. It had been a hot and humid day. I immediately thought it might be the heater core, and sure enough, the passenger side carpet was completely soaked. But there was no smell of coolant. And it did not overheat; the temp needle did not budge from normal operating temperature during the remaining 100+ miles to home.
If the car has lost a lot of coolant, how can I know? Wouldn't the float level be the same "min" mark?
Thanks in advance of any response -

 

[rebidus]

talking with my other personalities - so, I've run water down the window outsides and no water leaking thru the door panels. Cleaned and ran water thru the drain holes at the corners of the firewall - they were not blocked. Removed the cabin air filter and ran water thru those drains, they were clear. I'm adding antifreeze as per BMW firections and those found on Bimmerfest, and will proceed from here.
Okay, good job, let us know how it goes
;-)

 

[rebidus]

I managed to get to the heater core without removing the dash, thanks to this link found on youtube

The black foam tape was soaked. I've ordered a Behr heater core and o-rings from FCP Euro. I hope the black tape comes with the core.

 

[rebidus]

I removed the heater core after ordering a new one from FCP Euro. The water-soaked carpet was due to the drain hole under the heater core being blocked. It was not the heater core at all, but condensation from the evaporator had nowhere to go but out the plastic casing and into the interior carpet. I replaced the heater core anyway as the old one looked very shoddy, and the foam tape had disintegrated. I found a video (in German) describing the installation. Followed it to a T, but I had some trouble sliding the clips into and over the flanges of the inlet and outlet pipes. Seems the flanges of the pips were not fitting flush into the heater core. I forced them on (scary) and yesterday I drove the car at often high speeds (3000-3400rpm) for a couple hours o interstates, a few long uphills, in ambient temps of 80 degrees, with A/C on. I bled the system after installation of course. No issues.
Fingers crossed.