1980 300SD---Noise during acceleration sounds like a rod knocking. Using a steheoscope I determined that #5 injector was knocking much more than the other 4 were. Replaced the injector but now have an even loder knock while idleing again # 5. It smooths out at about 1600-1800 RPM. Heat seal came with the $53. injector and was replaced. Valves are in spec. Any idea what is causing the new injector to knock. Thanks very much for your assistance. Nate

If in fact it is not rod knock, and given your description, yes it would most likely be one or more injectors. However, you didn't say whether or not you had the injectors balanced so I'll assume you did not. I would find a diesel repair facility and have all five balanced together, making them equal to one another.The one new injector you bought is not likely going to match the other four.

The new injector however should not nail, or knock as you describe, even if it is not balanced with the other four. The injector you bought is a rebuilt injector, as I understand that brand new Bosch injectors are well over a hundred buck each. More common from almost all parts suppliers are rebuilds.

Now, here is the catch, lately almost all rebuilds are coming thru using inferior India made nozzles that replaced the original German Bosch nozzles inside the injector body and as I understand it, if you buy a whole set of injectors, maybe one, and if your lucky maybe two of a 5 injector set will function properly!

Sound bizarre?

It may very well be that you are hearing a loud rebuilt injector, and hopefully not rod knock.

Do a search here on injectors.


Steve..................

Thanks for your response. I purchased the injector from fastLane and it came with Bosch warranty card. I plan to move the injectors around to see if the noise moves with them. Thanks again. Nate

I would also try running a can of Diesel Purge in the engine. Do not just put in the tank but run it thru the motor only, see the directions in the Performance Products catalog. I did this in my 240D and the nailing stopped. Once I returned to standard fuel system the nailing returned.

As it turns out I had 2 really bad injectors and the other 2 were suspect. I guess with over 200k on them it was time to just replace them all. Replaced all and the motor stopped smoking on startup, nailing gone, and a load more power.

Simple and cheap test.

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79 240D (no name yet) 203K Miles Maple Yellow
98 2500 4x4 HD Dodge 24 Valve Cummins TD
83 Chevy Van (Dead-Trans. shot)