The MTC/Aftermarket cartridges are also well known for being junk. They close too easily and will stay shut even if the controller is not calling for heat. It is often suggested to transplant the rubber from the MTC aftermarket cartridge onto an OEM core.

__________________
Current stable:
1995 E320 157K (Nancy)
1983 500SL 125K (SLoL)

Gone but not forgotten:
1986 300SDL (RIP)
1991 350SD
1991 560SEL
1990 560SEL
1986 500SEL Euro (Rusted to nothing at 47K!)

Gone and wanting to forget:
1985 524TD 167K (TotalDumpster™) [Definitely NOT a Benz]