1989 mecedes benz 190e, changed distrib cap rotor button and plugs, but doesn't want to start when warm out?

You may have a cold start injector problem. The cold start injector puts additional gas in you system when starting the car in cold weather. It's not needed in hot weather, Try unplugging it the next time you start.

Good Luck

I guess it your it is deu to engine overheating. Most of the time Engine overheating causes serious engine damage. In order to avoid the engine overheating:

Check the coolant level periodically. It should be at least at the "min" mark in the coolant reservoir. If it's lower, add the coolant bringing the level to the "max" mark.

Caution: Never open the radiator or the coolant overflow reservoir when engine is hot!

If you discover a coolant leak, have it fixed as soon as possible - it may cause engine overheating.

If you note that the engine temperature starts rising higher than normal, have your engine inspected before it will cause serious problems.

Check the front of the radiator - sometimes it may be obstructed with leaves/dust. It's one of the possible reasons for the overheating.Hence your car does not start.

Check out reference for more info

If it will start but its a hard start it could be something as simple as a sensor, look into a coolant temperature sensor and your 02 sensors. The computer in your car talks with these two sensors, oh how rich/lean fuel should be based on the Coolant Temp Sensors reading on how hot or cold your motor is. Also, is your engine light on?

the most common problem are the injectors and fuel pump check valve that is leaking gas internal when u turn off the engine.this will flood the engine with gas or starve the engine with gas when the engine is off which cause your car hard to start .

if your car is a injection model you may have faulty injectors