Technical horrible rattle from engine

[jonjg]

hello. just wondered if anyone had any ideas what this awful rattle noise is. ive posted it on tube:

[ame]https://youtu.be/J5nlmV5kkVQ[/ame]

its coming from roughly the cylinder head. ive checked the cam and cambridges, they are ok. wondering whether its the tensioner or waterpump has had it? any help would be great. its about 4 billion decibels.

 

[portland_bill]

Never easy to diagnose by recording.
Thoughts:
Is the oil supply to the camshaft ok. You say you've checked the cam and its bearing housings, so hopefully it was very oily in there. Might be an idea to check valve clearances, although if slack, I'd expect more of a knocking noise.
Favourite would be water pump, but surprising it could make that noise without leaking.
Cam tensioner would usually rumble or squeal.

Next step is to get the cambelt covers off. Then check the tensioner for any play at all, and the water pump likewise. If it needs either pump or tensioner, would recommend doing both and cambelt.

 

[jonjg]

yes thats true. i have checked the oil supply to the cam,its very good and very oily in there. il check the clearances tomorrow. out of interest, why would bad clearances give a knocking noise.
i will get a new pump aswell, where would it usually leak? there does appear to be play in the pump when its running, i.e, the belt roller doesnt turn true, much like an unbalanced wheel wobble to it, if that makes sense? cant think of any other way to describe it. how would i check for tensioner play?

 

[portland_bill]

Your description of the pump roller is almost certainly the source of the noise.
Behind the pump pulley will be a hole in the casting to allow any coolant leaking past the seals to escape. However, it is hidden behind/inside the pulley, so unless the leak is significant, the escaping coolant will evaporate from the heat, as it will generally only leak when running, so when hot. Don't worry about that though, if the pulleys are wobbly, replace pump, belt and tensioner.

Probably no need to check the valve clearances in light of your other description. There must be some clearance to ensure the valves fully shut. If the clearances get too big, the cam tends to smack the follower rather than push it, causing noise. However, on overhead cam engines, the gaps are more likely to close down if the valve wears into its seat in the head, so getting potentially quieter, until valves no longer shut and a misfire starts. This is why clearances should be checked, although the need to rectify anything is rare.