My '91 300D 2.5 has become noticeably harder to start when the engine is warm. It eventually starts, but it cranks for a lot longer than it used to before the engine lights off.
The glow plugs aren't the problem, since the engine fires right up on cold mornings. And I doubt it's the battery, for the same reason. Either pressing the accelerator or not pressing it makes no difference.
Any ideas?
Thanks, Geoff