1975, 240D Mercedes, Engine cycles up and down - PeachParts Mercedes-Benz Forum

#1 03-12-2002, 04:42 PM

Question: My 1975 Mercedes 240D Engine cycles up and down so that once I give it some gas while in gear the car goes fast, slow, fast uncontrolably no matter how hard you keep your foot steady. The engine also cycles like this if in neutral. The engine does idle OK though, although the car really super smokes exhaust until it warms up.
I blew the air line out that goes from the air intake manifold to the injection pump. This helped but still same problem.

History: Car ran great untill I blew an oil line going to the radiator cooler and oil blew all over inside of car engine (I did shut the car right down). I cleaned the entire engine. Some oil did get suck into the oil filled air filter. (Note: This air filter is designed to have about like 1" of oil in it, the rest is like a brillo pad where the air has to pass through it in order to get to the manifold).
I see the line going to the air injection pump has a venturi nozzle I made sure was cleaned out. This helped.
I have driven the car for about 1,000 miles but same problem persists. The car runs OK once you are going full throttle. However, semi buckles as you increase speed.
But again have to give it full throttle or let it idle.

I brought it to one guy who works on Mercedes. He just charge me to increase the idle rate. Didn't help.
NEED HELP!!
Question: Can I spray any sort of cleaning solution into the air line going into the injection pump. Is that the problem?

mbdoc · #2 03-12-2002, 06:47 PM

There is a vacuum diaphram on the rear of the injection pump that controls the fuel mixture on this engine. Sounds like the diaphram has a split in it.
The part number is 000-075-06-07 & takes about 1-1.5 hrs to install.