Many of us have replaced the all important tensioner on our 164's with the mechanical type and while the jury is still out regarding which is better, hydrolic or mechanical I wanted to remind people that one should probably replace the idler bearing sooner than later. About a year and a half ago I replaced my water pump and should have put a new idler in too but did not. Last weekend my dad drove my L to Orange County and back and while north of San Diego he encountered stop and go traffic and 92 degree heat. Well the idler bearing siezed and the car over heated. Thank goodness the head gaskets (So Far) have not melted and a used but newer bearing has been installed to good effect. For a few bucks $78 at Di Fatta and a half hour you can avoid the almost catastrophic meltdown I almost had to visit.