Say a fella had a '79 300d that seems to run pretty well. Starts up decent (glow plugs probably need replacement) but gets fairly poor fuel mileage (I know, valve adjustment is probably in order). The current injectors have probably been in service for 110k since the car got a factory new motor. Now what if the same guy was on a very tight budget but had access to two sets of injectors, five each from a '79 and '80 300d of which he knew nothing of the condition? Would it make any sense to take all five injectors, have them tested and make a good set out of the ten? Or would this fella spend as much having them tested as he would pulling the existing injectors and having them rebuilt. Or, should he buy five used injectors and new nozzles and attempt to rebuild himself and then have them tested? Obviously, this fella (you guessed it, me) doesn't have the know how or access to a pop tester to test them himself.

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1979 300D 275K