Hi, I'm worried about this knocking noise coming from the front passenger side of the engine i think, hoping its just injector knock but it is just as this guy explained it in this post,
http://www.peachparts.com/shopforum/showthread.php?t=260409
basically an almost rhythm knocking at idle and at 1400-1800rpm a random noise and anything above that its gone no signs of knocking, now its really bad when cold but after driving over 30 miles or so at highway speeds and you stop its gone then it will come back if sitting idling etc. but one key thing is when i run diesel purge on it the noise is gone so hopefully that just could mean injector nailing. it has fresh fuel filters and i always check the oil level. and it just hit 200,000 miles also its a 1984 300d, all around town so about time for injector change, but if this was in a gas engine i'd be very worried it sounds very bad and i'm going on a 2,000 mile trip in 2 weeks so just looking for some tips and if its even safe to drive all the way.
if anyone has any ideas defiantly would be appreciated

not a rattle right?
a rattle could be the air filter bracket.
knocking could be injector nailing, it could be many things.
can you loosen one injector nut at a time at idle and have it stop on one?
how recently have your valves been adjusted?

defiantly not the bracket just put new mounts etc and about 3000 miles ago valves adjusted and will try cracking lines one at a time later tonight but the thing that got me was it goes away when running on only diesel purge

Thats because your getting less combustion on the purge. Let us know how the injector lines go.

__________________
http://superturbodiesel.com/images/sig.04.10.jpg
1995 E420 Schwarz
1995 E300 Weiss
#1987 300D Sturmmachine
#1991 300D Nearly Perfect
#1994 E320 Cabriolet
#1995 E320 Touring
#1985 300D Sedan
OBK #42

i cracked all the lines and it stopped the knocking when i opened #6 so thats the bad injector i guess

1984 300d doesnt have a number 6? You should update your profile and list your cars and location in your sig.

__________________
http://superturbodiesel.com/images/sig.04.10.jpg
1995 E420 Schwarz
1995 E300 Weiss
#1987 300D Sturmmachine
#1991 300D Nearly Perfect
#1994 E320 Cabriolet
#1995 E320 Touring
#1985 300D Sedan
OBK #42

Typo, meant #5

what does this mean, to crack all the lines? I am having a similar noise...happens the worst on diesel and with the engine cold. It's softer when I run on veggie oil... I haven't noticed any change in power...

metal lines have nuts connecting them to the injectors. 17mm loosen them, i.e. crack them a hair... this stops fuel from entering the injector on that cylinder and it'll either stall the motor, or cause the noise to stop as you loosen them.