300tdi Defender 110 - Another knocking noise question

My 300tdi starting making a knocking noise after driving it for about 1 minute. As it warmed up, the noise got louder and more distinct. It's a compression sound, definitely not metallic even though it's hard to tell in the video. Any ideas?

Here's another video at idle

Sounds like its chuffing, cylinder head gasket down the back of the engine.??

I was afraid it might be the HG...would I be able to feel any air coming out between the header and block?

OneZero said:

I was afraid it might be the HG...would I be able to feel any air coming out between the header and block?

Click to expand...

Bit of flour or talc helps
If it’s the gasket it’s not a hard job

Just checked and I'm able to feel air pulsing out the back of the engine
Now to order a new HG. I'll look for some tutorials on the site. Thanks for the help!

OneZero said:

Just checked and I'm able to feel air pulsing out the back of the engine
Now to order a new HG. I'll look for some tutorials on the site. Thanks for the help!

Click to expand...

Its not difficult , the rave manual helps a lot. Plus there are quite a few Youtube videos.

Cleanliness ,taking your time and getting the torques right.

I fitted the layered metal gasket.

Cheers