I recently purchased a 1982 300TD. I took it to my local mercedes shop to have it checked out only to be told not to put any money into it. The garage feels the car isn't worth fixing. I drive the car daily without problems, most of the problems the garage found were steering and suspension related. I would like fix this car up myself. But I want to first check things like the timing chain stretch to make sure this thing doesn't die soon after I put money into it. Can anyone one here explain in layman's terms how to do this?

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Just bought my first MB,
a 1982 300TD with an odometer that stopped working at 365,199 miles.