Hi Henners, Hope you've been enjoying your 840
Q1
- does the coolant/glycol smell get worse when heat is turned up? is there any fogging on inside of windscreen with warm engine and heat on high?
- ask mechanic to check the microfilter assembly, check the hoses that connect to the auxiliary coolant pump and heater core
- check heater control valve, often replacing this fixes problem and is lot cheaper than replacing heater core. (i would do this first)
- note also a while back, BMW issued a recall on the radiator cap to reduce system pressure during high temps. There was a tendency to overpressure the system and rupture the heater cores. I have heard of some owners letting engine run for 5 min with cap off to equalise system pressure after coolant change to fix smell problem too! If this cap has not been replaced you may be eligble for warranty claim on heater core.
- if you do need to isolate a leaking core: Turn off HVAC system ("0"), then dial the drivers heat dial to full cold and then into the detent. This powers the heater valves shut, other wise the E31 will activate the system in the background automatically to lubricate the seals.
Q2 - Sorry, can't help there. My only advice is if you need to travel further to find a dealer with a mechanic that has experience working on an 8 then do it!
Regards
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