#1cylinder is knocking hard. If I kill the fuel it gets quiet and idle gets smooth! !! What do I need to do? I set timing with lock pin tool at 15 degrees atdc.also replaced its injector. What next?

Smell the exhaust for lube oil burning. Head gasket may be leaking.

Move the injector to another cylinder and see if the noise moves with it.

Delivery valve on the injection pump may cause that problem, not sure.

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Present
1987 300SDL
1991 300SL
1990 560SEL
2001 ML320

Past
1969 200D 1979-82
1983 300SD 1984-85
1972 250C 1982-02
1995 S350 2011
1997 S320 2012

Tried that, no knock on other cylinder, it does have some black smoke.and a dead miss fire.tried remove injector tubing to that cylinder. It runs smoother on four cylinders. Put tubing back on injector and it knocks hard ! I started this project because cylinders 4-5 weren't what seemed to me getting enough fuel. So I took an injector pump from Mrparts car and installed it. Never could get the timing right. And I couldn't use the lock pin tool on it, different year Model .so back to origin injector. I rebuilt the fuel pump. But know the knock issue

I also checked and reset valve lash. And checked timing chain slack only a half degree slack.

Study using the milli volt method in the archives . Sounds like the first cylinders fuel calibration in the injectiion pump may be way off.

You are right in that the timing in of that injection pump would have been hard to find an acceptable place. Doing what I think will need done is important as accuratly as you can as the number one injection element is your pumps drip or lock timing refferance.

By ear is not going to get you close enough I suspect. You want that number one cylinder runing at the same temperature as the other cylinders. So you have all your soldiers lined up. Also have a close look for any paint markings on the number one element adjustment if there.

I just noticed you have the 603 injection pump with the internal but acceptable and accessable adjustments. I would also change the delivery valve seal as well on that number one cylinder before starting to go further. You have to or should use a dial caliper gauge to determine the start of the element adjustment if you have to go that far.

Semi starvation of the number 4 and 5 elements of the last injection pump. Did you ever check for adaquate fuel pressure with the old pump? Or run the old pump on vegatable oil to check for worn elements?

Wow. Sounds like fun. Thanks so much. Back to work!

Wow. Sounds like fun. Thanks so much. Back to work! Going back to 617 pump from scratch. Now I'm in over my head a bit, have some reading to do.Thank You! !!!

My mistake as I see you have a 617 type inection pump. No changing any delivery valve seals and the element adjustments are located where the hard line meets the element on the injection pump. Also did you disturb anything other than the hard line nut when you went to drip time that pump. Like the two nuts right beside the number one element? Or overtorque the hard line moving the base the hard line is attached to?

I had similar symptoms in both my 617 300td and my 603 s350, what solved the problems was some putting in additive and taking the cars on a 375 mile highwaytrips and the knock would go away. injector swapping and Italian tune ups wouldn't work but a nice long trip made them quiet.

hope that helps

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1974 240d
1983 240d -sold
1989 420sel with om606
1994 s350 turbodiesel - sold

Possible over torque line connector nut. No element movement that I know of

Recheck and moved pump to retard timing.its better no loud knock. I didn't mention wvo.use does that mean parts replacement?

No as the element for your number one element sounds like it is producing more fuel earlier in comparison to the others. If damaged from wvo it would have a failure mode where it was producing less fuel in my opinion.

You do not want to run long term with one cylinder running a lot hotter than the others as well.