Daniel,

Don`t wait to replace that tensioner. If it is rattling you need to address it IMMEDIATELY! I had the same situation, except someone drove mine for a while with a rattle before I acquired it. That little rattle ended up breaking the upper chain guide. Had a nice discussion with Benzmac who stated that if the upper rail is broken..so is the lower. Sure enough the lower rail was broken and two of the lower pins were cut in half. If you plan on doing the work yourself, GOOD LUCK. This is the worst car I have ever worked on BY FAR! In order to get to the lower guide most of the major pieces of the motor need to come off. Needless to say it was a nightmare. If you replace your tensioner NOW and avoid the broken rails you will save yourself much money and time. Replace it with the latest style ratchet tensioner and make sure you reset it and install it correctly. It is one big nut next to the alternator. Tinker