Annoying Accessory Rattle
Hi Guys,
This is my first post, despite being a member for a couple years now. That’s due primarily to the awesome pool of knowledge (and valuable search feature) at this website. Literally every time I have come here with a problem, I began by searching and ended up locating the answer without ever needing to post the question. I’ve been able to perform numerous repairs, retrofits, and upgrades. It’s incredible how many problems and symptoms are common.
Today I have a problem that I think is common, but I’m having trouble definitively diagnosing and resolving it. I have an annoying rattling sound coming from one of the accessories at low rpm (basically only at idle, and just off idle when letting out the clutch to drive away in reverse or first). The lower the RPM’s dip, the louder and more prounounced the rattle gets.
When I operate the car with the serpentine belt removed, it completely goes away (which is good news, since at least that means it’s not anything internal to the engine). Then with the belt off, I checked all the pulleys, and they all seem tight (no wobble) and spinning quietly and smoothly. With the belt back on, I have a good mechanics stethoscope and the rattle sounds strongest at the belt tensioner.
How can I definitively conclude which of the following is my problem:
1 - The tensioner assembly (the type with the damper piston) has gone bad.
2 – Or the tensioner is fine, but the pulley bearing is bad and needs to be replaced.
3 – Or perhaps some other pulley bearing (idler, water pump, etc.) is actually bad.
Please let me know your thoughts and suggestions.
Thanks very much,
Mark in North Atlanta.
2004 Chrysler Crossfire Coupe – Six Speed – ~127k miles.
Owned for two years – Completely stock except for stereo.