Early morning rattle
A cold morning start in my 2005 Corsa 1.0 revealed a rattle from the camshaft. The noise disappears almost immediately, but the clatter from the top end confirms that something is wrong.
I have been informed that a repair would entail a complete top end replacement, including the head. Apparently the whole assembly is matched for tolerance, etc, at the point of manufacture. On the other hand, Autovaux is able to supply either shaft, in which case I have been misinformed and a cheaper form of repair would be available. However, continuing to use the car while considering the situation would probably increase the wear on the journal and perhaps the housing. WHA Burgess There are two areas that may be causing the noise, one due to the timing chain and the other due to a gap between the camshaft and followers. As the noise disappears quite quickly after start up this would suggest the noise is only apparent before the full oil pressure is attained.
This could still be due to either slackness in the timing chain (taken up when the tensioner receives oil pressure) or else cam followers that are draining down. If the camshafts were worn the noise would continue even after the oil pressure was up to operating level.
You do not mention the mileage on your engine, but if the noise is coming from the camshaft follower area and not the timing chain, I would consider using a lifter-free additive to see if this will ease things. It would, of course, take an inspection to ensure the camshafts were not worn, but given the details you have supplied, I would be surprised if this were the case.
If the camshafts are worn, then the camshafts and lifters will need to be replaced. As this is obviously an involved job, it would also be worth replacing the timing chain at the same time to avoid problems in the future. The camshafts and followers can be replaced without changing the cylinderhead.