Assuming your car is similar to my 87, 260E. Maybe disconnect the coolant temp sensor connector from the sensor. If it starts without it great, if not, let it start and then take it out. It should put the car into a limp mode which I am assuming should be a high reliability low performance mode of operation. Will get you safely across the railway tracks, I hope. I am not sure where it would be on your car, but on my 87, 260E, it is the last sensor on the engine, towards the winshield, on the intake side. It is a two terminal connector.

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Saumil S. Patel