L322 td6 loud tapping sound

Hi all, im new here so please bear with me if I mess up
I have a 2004 l322 td6 auto & on idle & also right through the rev range there is a distinked tapping arround half engine speed , ive stripped down top checked cams &replaced liters while I was there x24 rebuilt started up & the damn tapping is still there, I have had hours with the stethoscope on it now & im now convinced its coming from the bellhousing , or is the bellhousing amplifying some randome fault with cyl 6 ???????? Im lost do I pull out the box & torque converter .?????? Can anyone help me , thanks for reading my rant but its driving me mad

Might be an injector knocking?does it misfire ?smoke?

Could possibly be a small end worn

Hi dove, no no missfire, no smoke , car drives lovely as there is no fault there,

Hi ovalandrover, I think were on the same ideas, think I'm going to putt off inlet manifold & do a compression test on her,

I have read on here that they tap with a duff injector. Does the tapping change between neutral and in gear? If so maybe flex plate.
If the injectors unplug, try unplugging one at a time and see if the sound changes.

Hi datatek , yes I would have to agree there is a deal of injector noise from the engine but the one that's standing out is a really metallic sound, ill try & upload a video with the noise later for you all to hear it, I have also thaught flexplate but went away from that idea as its really in time with engine just 1/2 engine speed I will check the flexplate bolts while doing a compression test, am I right in thinking u can get to the bolts just below starter motor in that little hole , thanks for all the help guys this is driving me mad

I have allso unplugged injectors one at a time & fitted a noid light to check wiring & noise is still there on all 6 & noid light illuminating perfectly on all 6, sorry I should have mentioned this from the start, I'm stumped lol

Double check the cam timing - also it's not unheard of on these engines for the timing chain to stretch leading to a value or two tickling a piston. If you've got access to an endoscope have a look for any witness marks.

Update to all reading, carried out compression test, all cylinders ok, pulled off head, everything covered in carbon buildup ide say to the point its probably crushing the carbon between top of piston & head everything going for cleaning, no bent rods tho as all pistons travel to top & pertrude 2mm from head, no bent valves, all seated nicely, also found x2 vaccume lines sucked closed 1 running to egr selonoid from main thick vac hose under inlet manifold & other from same hose to engine mount blocks

I didn't think carbon build up was normal in a diesel engine - I think you need to look for the root cause of this one....

Cheers

Jerry

Hi jerry thanks for the input, I think I may have accidently.found the cause while doing the job, found the vac line to egr selonoid crushed together ie no vaccine passing through when checked with mitivac & egr valve was wedged stightly open allowing a constant pass through of exhaust gasses into cylinder, putting head back on tonight so I will be updating, I will keep this thread going till I find the fault & I'm happy its cured as I know how annoying it can be to have a rare fault & never find a solution / cause , thanks again for all the input from all,