Hey all,

I'm chasing down a sound that resembles a small diesel or clatter and looking for some advice. Recently took my Mini into the shop (Helix Motorsports, who are excellent to work with) to have the control arm bushings replaced and had them try to diagnose this sound at the same time. They seemed to think it was the tensioner making the noise, but I held off having them replace it so I could just do it myself. Swapped it out for a new one last night but the noise is still there. 160K miles on her.

After putting my ear to the end of a screwdriver, it doesn't seem that it's coming from the actual engine, but instead potentially the alternator. What's the likelihood it has a bad bearing, or that it's another component running off the belt? I also had recently replaced the timing chain tensioner because I'm aware those are a known fail point, but that didn't make a difference (fairly certain it's nothing to do with the timing chain). At this point I may just drive it until something breaks, but that noise is testing my patience every time I get in the car.

 

Do you have a probe? Did you put the screw driver right up to the alternator? It definitely seems to get louder in your video when you look at the alternator/pulley area. To me, it sounds like you might be on the right path about your alternator, but you'll want to try and isolate the noise as best as you can. David has some good advice at post #9 here that might help you diagnose it. Maybe see if that might help.

 

I don't have a probe, but yes, I did put the screwdriver right on the alternator. Listening through the end, the sound seemed to resemble the external noise I'm hearing, a lot more so than anything else I placed the screwdriver on.

And thanks for the link to the post, that sounds like a good way to diagnose without dropping more cash right away on something that might not be the problem! I'll have to see about pulling the belt and running the engine briefly.

 

Just wanted to post an update. Wouldn't you know, I was driving home from a long trip last week and my battery light came on. I ran some basic tests and confirmed the alternator went bad. I pulled it out to make sure I'd be ordering the right part and while I had it out gave the alternator pulley a spin. It produced the same noise, the bearings must have gone bad.

I ordered a new alternator and put it in. Boom. No more weird diesel/clatter sounding noise at idle. And more importantly, my battery was charging ha.