Engine clunking!

[Carnie]

Ok,put a few posts up about this already but we still havent figured it out.My mate left his car sitting for a while and on start up it was making a loud clunking noise in time with the engine(up and down with the revs etc)We put this down to the tappets and let it run for a while and it cleared up and went away.Anyway this has happened again now after he left it lying and it wont go away(let it run  for about 10mins till engine was warmed up),we tried tappet treatment,that didnt work.We checked the cam and all the tappets,their fine,all valves move and no damage or give to any of the lifters.Everythings getting good oil flow.Next checked the big ends,no movement,only side to side a little but im told this is normal,oil pick up is clean and oil pump is working.Checked all the pulleys etc theyre all good.Filled it back up with oil etc and started it up and the engine is still clunking away.Really cant think what else it could be.Next step would be to take the head off but he just did the head gasket a few months back so he'd rather try that last.Any other suggestions?

[Alec]

Might be time to whip the head off. Sounds like something is worn.

[Carnie]

When he did the head gasket before there was no sign of wear at all,all the cylinders were smooth,no ridging,pistons looked in perfect condition.It just be the case,we ll take the inlet off and have a look through to the valves,maybe we can see the prob there but i doubt it,head might just have to come off!

[warnesey333]

Compression test? Could show if something is wrong with a particular cylinder.

All the pulleys are tight on? No wobble?

And it's 100% from the engine? Not any ancillary parts?

[Carnie]

Yeah all pulleys are tight from what i can see,checked the alternator tensioner and that seems fine too.Clunk is almost def coming from the engine but i dont know where,cant be anything else as nothing else would cause that clunking noise etc.Its lounder when under the car also.Would the water pump maybe cause this if it had gone?Never heard one thats bust so unsure.Is it possible its a crank bearing,again never heard a bust one.Just cant think of anything else in the engine that would do this.Ill maybe try get a recording of it to help.

[DOA]

Sounds like tappets to me (though they dont clunk, they tap lol). Have you actually re-built them or replaced them? How thin is the oil you are using and have you tried any thicker stuff in there. Mine are a bloody nightmare but I just cant be bothered changing them (and will doubtless find some rather flat cam lobes when I do).

[Carnie]

We just put some 10w40 in there so i wouldve though that would be thick enough.The oil that came out was shot to pieces so i was hoping that would work but no difference.We thought the tappets at first but its too noisy for them i think,i mean theyre hydraulic and theyve got like 0.4m of movement so theres nowhere for that clunk to come from?

[Wayne]

Worn small end bearing ?

[clipperjay]

Yeah money is on the small bearing check the con rods main bearings if your planing to go diving!
If you drain the oil out to do the bottom end, check it for small bits of metal?
 

[Carnie]

There was no metal at all in the pan when we had the sum off last time.Take it theres no real way to confirm it is the small end unless we start pulling pistons out yeah?