If compression is a little low, no matter what you do you wont get it to run perfect when its cold, ie, you will have to stay with it till it warms up a little. All of my mb's are tuned; chain stretch, valves, ip timing, and new filters. My sd with 367k will start in the teens but I nave to stay with her for a little while. My td with 50k on the engine will start in single digit temps without ever touching the pedal.

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a few mb diesels