We (well it's my wifes really, I just pay the bills) have a 1981 280CE, very low mileage, not much used, regularly serviced, fitted with "Fuelsaver" widget recommending for running on leadfree.
It starts fine from cold: it might take a few seconds for all six cylinders to come to life, but it's not bad.
It starts fine from hot: instantly.
BUT When it has cooled down to between 60 & 80 on the temperature gauge it really doesn't want to go. You can turn the engine for best part of a minute, and use all sorts of combination of pre depression of pedal, or gently dabbing the pedal, and get nowhere at all. When it finally catches it pretends there was never a problem at all and is fine.
I've been to three places, an independent Bosch injection specialist, a hole in the wall independent Mercman, and a main dealer with a "30 years on Mercs" older type of mechanic. None of them can crack it, and think we're making the problem up, because it is difficult for them to simulate.
Between them they have
Replaced the non-return fuel valve.
Replaced the fuel distributor.
Replaced the rotor arm and distributor cap.
Replaced the "Cold start controller".
Done various other stuff like timing and new plugs.
I'm sure someone has come across this problem elsewhere. Any help??
I'd appreciate any help very much - as you can tell I'm not a technical type and I am losing face with her indoors. Apart from that the car's a dream.