mercedes w115 200 1976 cuts out once hot after 5 mins starts again

[Doug1234]

Take the fuel tank cap off and run it , may be tank cannot breathe ?
My main thought would be carb float / needle valve sticking, they can look good and perfectly ok but give hassle.
You mention it runs ok but cuts out after driving then you are also possibly using more fuel than it can get hold off or it has a major vacuum leak somewhere although this should cause a misfire etc.
An engine even running lean as hell will happily rev up and appear ok until you ask it to drive and pull some weight.
I have never owned a petrol mercedes but running for ten minutes then dying does smack of the old moisture in distributor they all seem to suffer at some time, engine heat causes moisture to steam and short out inside distributor cap.. its one of the first things that get mentioned in someone posts up an older car has misfires and will not run when warm

 

[LostKiwi]

If you haven't already done so drain all the fuel and flush through the fuel system.
Varnish and dried fuel will stop most of the fuel system working properly. Remove the carburettor jets and inspect the float bowls for crud in them. Fuel more than 5 years old creates a lot of issues.
Once done replace fuel filters. Check fuel pressure at the carburettor.

 

[DREAMER NO2]

Change the coil

 

[W115whydideye]

Have you cleaned the connections to the ignition coil and checked the resistance..?

Hello, updated- it was an issue with the automatic choke. These things are a pain in the ar53. It wasn’t set up in the right position for the coil to move back from the arm that adjusts the mixture.

 

[rifiki]

If it has points type ignition it could be the condenser. Modern points are crap and don't last 5 minutes.
If the distributor is in good condition change to in distributor electronic system.
They make a huge difference to the motor, better starting, hot or cold and smoother running.
Have done this to a few old cars.

 

[W115whydideye]

Hello, updated- it was an issue with the automatic choke. These things are a pain in the ar53. It wasn’t set up in the right position for the coil to move back from the arm that adjusts the mixture.

Now I have the task of replacing the starter motor!
Seems like the car was literally built around the starter motor.
Had great fun working out the model number yesterday, those crucial middle three numbers were pretty worn down but the help of a local supplier we got there. Replacement arrives today for a decent (I think) price of £112.
Any advice on how best to approach this would be greatly appreciated!

 

[W115whydideye]

Starter motor removed and new one fitted. Took about two hours due to the restricted access, was a fiddly job but all done and works a treat.

 

[rifiki]

--"built around the starter motor" Car was designed to be LHD. Steering and gear change adds more obstructions