L322 Td6 engine noise, not lifters, maybe?.

so today I decided to strip the manifold off my engine to see if I could hear more clearly where my knock/ tapping is coming from,
Manifold off, engine starts, straight away I know something isn't right, it's blowing back on a cylinder, same noise as if I'd taken out an injector,
I covered each cylinder inlet individually and it's clear that number 5 has an issue.
I took off the rocker cover to see if there was any obvious issues but all looks fine,
I can move the valves fine, they all look the same height, there isn't any play in the rocker so lifters seem OK although I'm not sure I'd be able to tell,
Also if a lifter was faulty I'd assume the valve wouldn't open properly, and again I assume my issue has to be an Inlet valve not closing properly.
Anyone have any suggestions as to what my issue might be?

It does indeed sound like an inlet valve if it is blowing through the port!! burnt valve head/seat maybe. A compression test would confirm, unfortunately the removal of the cylinder head would be necessary for any valve repairs... It never rains!! It...

Just a thought, worn/sticking valve guide could be contributing....
Also if a lifter is faulty it can pump up as well as not pump up!!
Worth seeing if it does the blow back from cold, could indicate a worn lifter.

I guess with 230,000 a replacement head is a tad pointless,
Have to decide wether to chance a used engine or put this back together and fob it off to the auction

TD6 suffer with cracked exhaust manifolds , cheap cast iron ones available on Ebay

If it pulls strong and no knocking from the bottom end, refurbishing the head could easily get another 50k out of it.
Depends how good the rest of the block is I suppose.

Doesn’t seem any worse from cold, maybe a little better if anything,
Not sure exhaust manifold issue would cause compression to blow back??

Doesn’t seem to have any bottom end issues but is it worth spending many £100’s on an engine with this mileage???

Wazzajnr said:

If it pulls strong and no knocking from the bottom end, refurbishing the head could easily get another 50k out of it.
Depends how good the rest of the block is I suppose.

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50K out of a head? Thats awful

Could well be a faulty lifter on the inlet side..if its a little better when cold it could be pumping up?
Maybe, if you decide to have the head done, you could examine the lifters before you lift the head off and check if the inner parts move freely. I had clacky lifters on my old vauxhall x20xev petrol engine. The lifters after 180.000mls had become worn and the internals we're sticking and a couple had limited movement. After a new set of 16 all was clack free!!. Just a thought before lifting the head...

Ok that’s interesting,
Anyone know anything about taking the cams off without breaking them? I believe they are hollow so will snap if Just undone, even if the bolts are only undone a small amount at a time

Would that cause it to blow compression back through the inlet though?

If I bought a used head would it need to be skimmed?

Jammed open valves!

Possibly a bent valve or burned out seat maybe, they aren’t stuck because I can move them

The cylinder head if used should be pressure tested and skimmed to give you every guarantee it'll cause no problems when refitted.

youmitegetian said:

If I bought a used head would it need to be skimmed?

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Not if it isn't warped.

Check your lifters to be sure.

myfirstl322 said:

Not if it isn't warped.

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True, it's a lot of work to take a risk. Personally l3' I'd rather have it done and checked. You can check the surface yes.

Camshaft was put on so it will come off if done correctly.

Not sure these heads are even skimmable.

Would a set of followers to your existing not be more time effiecient?