L322 Noisy tapping engine, still

so I've posted this issue before and tried to sort it but not managed as yet
The engine has a noisy tap/knock
It's top end I believe, certainly cam speed not crank, I think a hydraulic lifter is broken as oil additive does quieten it down for a short time
It's been to a garage for them to look at, they came back with a possible injector knock.
My question is this, would oil additive quieten down an injector knock?
Also individually disconnecting the injectors doesn't alter the noise, and the injectors have been replaced recently for tested used ones and the noise didn't alter
The Garage were doing me a favour by looking at it so hasn't cost me a penny, just worried the advice might be incorrect, just interested in your thoughts

Sounds dubious to me.
Don't know how possible it is on your engine, but years ago, I used to slide a thin feeler gauge under tappets to see which one was noisy. (old escort cvh engine)
The ball bearing that kept the oil pressure in would wear and they couldn't keep pressure so they would tap.
Feeler gauge would highlight which one it was. Only a thin one mind, you don't want a valve hitting a piston!
And you do get oil everywhere and I guess that'll be much worse on a v8

Mines a TD6 not V8, I’ll look into that, it doesn’t look like a massive job to get the cam cover off so prob worth a look

OK, you might be able to do it then. You'll still get oil splashing everywhere but it doesn't take long and it might just point you in the right direction

So give me the run down then, I guess it’s a case of test the gap between the rocker and the cam lobe, if any show a bigger gap they are likely to be the noise??

No, I used to slide a thin feeler in whilst it was running and see which one made the tapping go quieter. That's why it's messy.
If it's cam directly onto the valve as some engines are, I wouldn't do it as the cam could drag the feelers in but if it's rockers and you use a 0.1mm feeler it should be fine.

Oohhhhhhh that would be messy lol
Is there no other way to test the lifters? Something that doesn't involve me taking a shower in oil !!!

Not that I've heard of but then I'm no expert on this engine.
If you suspect it's only one lifter, I don't think they're expensive. (I saw some for about 8 quid but not certain they were the right ones)
You could try a piece of wood on the rocker cover held to your ear and see if you can narrow it down to one cylinder then try swapping 4 at a time.
Then again, if it's a high miler and you're convinced it's the lifters, 200 folding ones and they're all new thus eliminating them from your enquiries.

Yeah the lifters are cheap, fitting them is the costly part, apparently you can’t get the cam out with special tools,
I’ve read they are hollow cams so if you undo the bearing caps it puts uneven pressure in the cam and snaps it,
Could be wrong but sounds feasible to me

Ah, right.
Might be worth a thread asking if anyone on here has said special tools that they would loan to you.

Is yours the BMW M51 engine? If so, wammers said in another post that you can remove the camshaft without special tools.

It’s the m57 but yes bmw
Is the m51 from the p38 maybe?

Ah yes, I was forgetting yours was the l322.
Not sure then!
Did have a quick Google and it does seem to be a common issue.
Might be worth an ask on ffrr.net or whatever it's called. I think they have more l322 gurus on there so a good chance someone had already done it and will know all the pitfalls.

Well the engine does suffer from hvl noise but usually only intermittent,
I think I might get a used head and fir that, they are cheap and can get a guaranteed one from a reputable breaker,
With the mileage my car has I imagine if one lifter has failed the. More will follow