2009 Volvo C30 R-Design with ~78,300 miles on it. No recent accidents, unusual events, etc. Regularly maintained at Volvo dealer, garage-kept.
Back in February I noticed a “thunk” noise that seemed to come from the front end. It was most noticeable at low speeds, seemed related to the suspension (more frequent on rougher roads), and would increase in frequency as the steering wheel was turned. Does not seem dependent on engine speed. A single, “thunk,” would happen just after moving from a full stop. It would also often happen right when coming to a complete stop.
I took it to my regular Volvo shop. They replaced both front struts, support bearings, and supports. Drove the car away from the shop and all seemed well.
Last week, I noticed the noise again. Exactly the same. Still seems to be coming from the front end of the car, maybe on the driver’s side. I heard one “thunk,” as I got out of the car on Monday, lending credence to the idea that it is suspension-related. I made an appointment to take it to the shop yesterday.
Driving to the shop, I thought, “great - it’s not making the noise today.” By the time I had driven 15 minutes or so it was back. When I dropped it off, my regular service guy could hear it. He told me later that he and one of the mechanics drove it around and could hear it clear as a bell.
He called yesterday afternoon and said it looked like one of the support bearings had failed; that maybe it was bad from the factory. They replaced the bearing (at no charge) and said they drove it around and there was no noise. Service guy called this morning and said he drove it again - no noise.
10-15 minutes after picking up the car, the noise was back, exactly the same as before. So, it appears to be something related to either temperature (the engine needs to be hot) or simply use; something works itself loose after driving and “resets” itself after sitting for a while. I can’t think of how that latter scenario might work, but who knows?
Any ideas? Is it possible that one or more of the engine mounts could be the culprit? We’re both scratching our heads. Headed out of town tomorrow, so I won’t be able to get back to the shop until next week, so I thought I’d poll The Dope and see if anyone has any bright ideas.