The W123 chassis covers 240D's, 300D's, 300TD's, 280E's, and several other models of Mercedes coupes, sedans and wagons from model years 1977 to 1985.

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converting petrol to diesel engine.

Hi, to convert petrol engine to diesel, is it possible to use the same speed box? Can its fit's the diesel engine?Both engine was same displacement.

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Hi I change my rd28 d turbo to a Nissan rb20 . what gear box can I use ? the vehicle has no power and can't go up hills.

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Yes. There will be many other items to work through, however.

The driveshaft may be a different length.

As noted the final drive gear ratio may be different, so it's hard to guess how it will perform.

You will need the diesel motor mounts, and will need to retrofit to add the motor shocks.

You will need to install an ignition switch that is designed for diesel cars and run vacuum lines to it so it will activate the diesel fuel injection pump vacuum shutoff valve to turn the vehicle off.

You'll need to wire up a glow plug relay to your ignition switch, or a manual glow plug switch.

You will need to make sure to install the proper vacuum line from the diesel engine's vacuum pump to the brake booster that includes T's for feeding vacuum to other systems like the shut off, door locks, etc.

You will need to install a return fuel line that runs back to the tank. You may need to install a diesel tank with a fuel return inlet. The diesel engines return un-burnt fuel to the tank (it's a circuit, not one way).

You will need to install a diesel fuel strainer in your tank, the gas fuel strainer is much finer mesh and will clog much faster running diesel.

If you do not have one now you may need to install an oil cooler, the diesel engines all came equipped with one and running without is not advised unless you live someplace cold year round.

From what I've noticed the gas vehicle radiators were smaller. You may want to install a bigger radiator, like one from a 240D.

That's some of what I can think of off the top of my head. There is a lot to it. You will have your work ahead of you!

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This answer was originally to another question.

sivaprakash, having done this conversion years many, many years ago, yes you can. Biggest issue is that the gearing is different. You will notice that you will be considerably slower to accelerate, but it will cruise nicely at 50mph.

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