Inconsistent engine (?) rattle

[Binks]

Hey yall,

I've got a fairly high mileage yaris (322k kms) that has a rattle on most but not all cold starts. Sometimes it doesn't happen at all though and it doesn't seem to matter if the weather is cold or hot.

It goes up with rpm and my guess is that maybe the timing chain tensioner isn't working great but sometimes it does its job and doesn't let it rattle on a cold start.

Just wondering if anyone has any input on the issue,

Thanks!