Clattery when cold
Join Date: Feb 2012
Location: United Kingdom
County: Greater London
It could well be, but equally it could be from a hose, from the EGR heat exchanger tube or thermostat, all of which are in that area. You're going to need to take a much closer look at all those bits, with the engine cold and not running. Easier with the battery out. Look for drips forming.
Keep a very close eye on your coolant level, and don't let it drop else you could end up blowing the head gasket, which is a major job.