88 22re with 238K miles. Timing chain makes a racket after a cold start up. Sounds like a somehwat soft rattle of nuts/bolts in a coffee can. It goes away rather quickly once I start driving. Serious? How much time do I have? With this many miles I am anticipating a rebuild at some point in the near future, so tackling this job alone really doesn't make sense. Is this something that could suddenly get worse and leave me stranded?