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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W123 proper diesel lift pump?

I am ready to clean/change fuel filters on my 1983 300d and dont want to rely on the primer pump [hand operated] and saw where a lift pump would allow me to close up the circuit after the change of filters and turn on the pump and let the air bleed out mechanically. would anyone know the right pressure these lines should have on the way to the injection pump? there is a video of a heated sump and pump for this but they were no longer available for sale so it semms i have to piece these parts .

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Hi, interesting idea. However, I think you're over-thinking this big time. If you follow the fuel filter change guide and fill up the large spin-on primary filter with some type of fuel before re-installing it you may not even need to prime the car. I know last time that I didn't even bother pumping the hand primer and the car started right up. However, if you do need to prime the system a bit, it'll just take a few quick pumps of the hand primer.

As an aside, your W123 is a later model, so it probably has the black plunger style primer pump. If so, these work very well. If you happen to have the older white plastic screw style primer pump you should consider changing it out for the new style. There is a guide for this on the main W123 page. It's an easy swap, and only costs about $15. Then you'll have a good primer that you can rely on.

Basically, don't stress priming so much. Fill up the filter, pump a few times, and then crank away!

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joe masterson will be eternally grateful.
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