I thought the new battery helped alot in mine until I had the starter reworked (we really had to overuse the starter to get the car running after it had been sitting for 3 years), now it really spins. Starts very well until temps are in the teen's and then I have to roll it off the starter.
Valves are next.
You might do a search on this problem, there is a lot of info already on this site.
One thing I read here that seemed to help me was when it is very cold compress the pedal three times and hold it part way down before trying to start.
The other suggestion I see a lot is to cycle the glow plugs a time or two and leave them on an extra 30-45 seconds before trying to start. I don't know how this works since mine is setup differently. (1976 240d)
1970 Duetz Tractor Air-cooled diesel best tractor ever made.
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1976 240d miles?? fresh paint
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