Hello friends, Iīm spanish, I donīt speak english very well sorry. My question is if I can put a rpm gauge in my car, this is a 1982 300D no turbo, in spain its very dificult to see a car like this with a rpm gauge, can you help me? thanks from spain

Hi, nobody can help me?

rpm gauge in a diesel is more difficult than a gas engine.

In a gasoline engine, there are electrical impulses and sparks for a gauge to sense and measure. In a diesel, there are no electrical pulses that occur naturally.

Diesel rpm are sensed at the flywheel, using a sensor near the gear teeth.

Since no gauge was fitted for your model, it will be very difficult and expensive.

Best Regards,
Jim

Some OM617 engines I've seen have a pin in the crankshaft damper (front pulley) that is sensed by an inductive pickup sensor mounted to a bracket on the engine block. If yours has the pin, you can get the bracket, if not already present, the inductive sensor, the signal amplifier and bracket (mounted on the fender wheel well), and the tachometer gauge out of a junked car. You would need to make a new wire harness just for the tachometer, and find a wiring diagram for that year for reference. In the US, as far as I know, 1982 models and newer all were turbos and had tachometers, so any W123 diesel 1982 or newer could be scavenged for parts. I have heard that later models, 1984 and 1985, used a different setup for the tachometer and may not work for a retrofit.

Otherwise, I'd agree with Jim H that it would not be worth the trouble.

OK thankīs from spain.