When I start my 1982 240D engine it won't start. I have to spray a little starter fluid to get it started. If I let it run for a minute or two and shut it off, it will start without the starter fluid. Leaving it off for a long time requires starter fluid again. Any answers or suggestions?

 

This is a very old thread, but others may have the same issue. It won't be detailed just general areas.

Make sure the Glow Plugs are working. There is the individual glow plugs themselves, there is the glow plug relay/timer and on the relay/timer is a metal fuse. Next when you turn the ignition switch to the pre-glow position is the glow plug relay working. You need to verify if all that is working as it is a system.

Next is since you have owned the car have the valves been adjusted. After they are out of warranty Mercedes owners often don't continue having the valve parodically adjusted. Next is when they sell the car the next owners may not think the valves need to be adjusted. If the valves are not properly adjusted, it affects you compression especially at starting and makes it harder to start.

Low compression will make starting hard, and a compression check would be needed to check that.

Next would-be low starter cranking speed. The common issue there is the contact areas of the battery cables and or grounds. They all should be taken apart and cleaned.

It is possible for battery cables themselves to be corroded inside and there is a test for that involving a volt meter but you should look on the internet for the test instructions.

Of course, if it is the starter itself it could need to be rebuilt. On mine I found the starter brushes were worn out and the commutator needed to be resurfaced.

That is enough for now.