I just installed a zerostart lower rad hose heater in my son's 240d the other day. It seems to be working fine. Although the weather has not been severely cold, he had to crank his car 3 x on the glow plugs to start it last cold spell. It now fires over on the first glow plug cycle. Also his alternator bracket tensioning fork was being bent and kept slacking the alternator belt. Today I welded a bit of mild steel on the top of the bracket, once I got the bracket forks at a 90 degree angle to the tensioning theaded rod. Stick welded it, worked like a charm. I wet a towel and wrapped the surrounding areas with battery and alt unplugged.
I surprised myself because the weld was so clean. I was gonna use a mig, but not practiced much. The stick was handier and I've done plenty of stick welding. No flux to crack off! May have been the cold temps. I don't know, but the welding went well. Tightened up the alt again, and no problems. he's 17 today with his now, senior drivers license.