1986 560 SEL (156000 miles). I have two problems. First, the electric fan runs all the time, just turn the key without the engine running and it goes (car not driven for a day, engine cold). Second the engine shakes a lot, it feels like a diesel, when I stop at a light the whole car shakes, I was told that it could be cheap gas.

thanks for any input guys.

jerry

 

you have a faulty temperature sensor. it is the one with the blue color seating on the thermostat housing.

you have a faulty fuel distributor. the amount of fuel injected on every port is not the same. if your rpm is below 750, adjust it. if rpm is fine, replace it.