w124 serp belt/tensioner - stranded in LA

[richard28]

Last night my son was driving the 1988 300ce on the LA freeway,and suddenly the dash board lights lit up. He quickly pulled over and was fortunate to be near and exit, and he went to a gas station and called home. When he opened the hood, he could not see the serp belt on any of the pulleys. He called MB roadside assistance, and for $120 the car was towed two miles to the MB dealership Keyes Motors in Sherman Oaks. The serp belt was replaced in New York by my indie about three/four years ago, and the tensioner has not been touched since then. I'm wondering if the belt failed due to the California heat or if the belt tensioner broke. Is the tensioner likely to break when the car is in motion, or only when it is being adjusted? Also, any idea of reasonable dealer cost to replace? Thanks.