First of all, I thank you all for your help with various Mini issues in my past. This forum has been great and though it's been a while since I've been on here I hope there are still helpful, knowledgeable people willing to answer questions.

I have been trying to address a noise in my engine bay for some time and I am at my wits end.

Please see the uploaded attachment. This noise sounds like it's coming from the top (or near the top) of the passenger side of my engine bay. It tracks with RPM but gets lost in the noise of driving since my car is rather loud once it gets moving.

The car has 160k miles on it and is already on its 3rd supercharger. The first lasted about 135k miles before it was sounding horrendous. Bought a rebuilt one from a reputable site and had a trusted shop install it. Within a few hundred miles it sounded awful. Contacted the site and they said they had a batch go out with bad bearings. Sent me another under warranty and I had the same shop install it. This one has been kinda loud (like in the video) since install but I feel like it's worse now, about 10k+ miles later.

I've tried other stuff to address the noise. Recently I pulled the supercharger off myself to check and change the oil. There were ZERO metal shavings in the oil and while it was dark it looked relatively clean. I added the recommended amount of oil on each side (if memory serves it is 145 mLs on the left and 40 mLs on the right?) and put everything back together.

Yesterday I pulled off the idler pulley and the old one immediately fell apart into 3 pieces. I was hoping this was the culprit but when I put it back together the noise remained. I also purchased a new tensioner assembly but didn't install it because I was so optimistic that it was my idler pulley. I guess I can throw the tensioner assembly in fairly easily if that's the consensus, though I doubt it.

My thinking is that this "rebuilt" supercharger is bad just like the one I had originally put in, but not quite as glaringly, obviously bad. I didn't pull it apart as that is beyond my comfort zone. I don't want that to be the answer, but I fear it is.

I will add: the car drives wonderfully. Pulls strong and if you turn up the radio and ignore it you would think nothing is wrong at all. It just sounds bad.

If relevant: the car has a 17% S/C pulley, 2% ATI crank pulley, WMW track cam, 550 cc injectors, and a custom tune to make it all work. Also a bunch of other basic bolt ons such as a full header-back exhaust, which explains why the car is so loud even when it isn't rattling itself to death. It has 277whp and is a blast to drive when I am not babying it for fear of blowing the supercharger up.

Thank you again for any and all help you can give!

 

Before you decide it's your S/C or not, check out the hydraulic rod that is part of your belt tensioner. As the tensioner ages, the bushings holding the rod on either end can dry out, crack, and fall out. The hydraulic rod can be purchased separately ($25ish) and replaced easily through the passenger-side wheel wheel after removing the liner.

 

Thanks for the reply. The rod wearing out was one of the reasons I bought the tensioner assembly, which I have yet to install. I guess I can easily swap out just that part of it, or the whole thing if necessary. Before I do that, I just wanted to get some experienced opinions from other R53 owners.

 

It does have a particular grindy metal noise. Likely possible to eliminate timing chain issues based off the sound, they tend to sound more ticky.

As @cooper48 said, tensioner is highly possible. Start here as its simple and you have the part. AC Compressor is another thing known to make a sound like this, when mine failed it sounded almost identical and was very hard to pinpoint with the entire front end on the car. There is not really much else on the belt drive system known to fail. Fingers crossed its something simple in the belt system instead of the dreaded supercharger bearings!

 

I guess it will be worth my while to try throwing in the tensioner assembly. Maybe I'll wait for another warmish day and get in there. If that solves my problem, I'll be overjoyed. Would be nice to stop babying my car and drive it properly again.

And if it's the AC, that would surprise me. I always keep the AC off because it tends to not blow hot enough unless I'm moving at highway speeds and overheats my car if I'm standing still. I think that's a side effect of having the larger crank pulley, since I didn't notice that until I did that mod. Then again, I did do the crank pulley along with a lot of other mods (cam, injectors, tune, and intercooler).

Thanks for the input!

 

i mean more specifically the ac pulley itself. The bearing inside can fail and it sounds absolutely awful, if left unchecked it usually eventually seizes and breaks the belt. Should be easy to notice spinning by hand and wiggling it once the belts off.

Even without ac actually running this bearing is always spinning. Worth a quick look!

 

That makes sense and I will totally check it out. Thanks for the tip!

 

I just went through something similar. I had a similar noise that I swore was the SC. Figured with 125k miles, wouldn't surprise me. When I removed the belt and spun the individual pulleys, all seemed good, but there was a little bit of slop in the SC. Ordered one from Detroit Tuned, swapped it in, and the noise was still there! My other thought was could be the alternator, and when i removed it to install the SC, I noticed a crack in the housing. If i spun it on a drill it would sound fine, but if i put a little bit of sideways pressure (simulating belt tension) it started making a rattle/knocking noise. Oh well. I just got the car so now at least I have peace of mind that my SC is good to go, and if it isn't, I have a 2yr warranty on it!

 

This is interesting. Did you end up changing the alternator as well, and did that solve the problem? If you wouldn't mind posting a video of the sound you have, I would like to hear it.

I still haven't had the time to get in there and try to fix stuff, but I hope to soon. Someone suggested I run the car (briefly) with the belt off and see if the noise is internal to the engine. I don't expect it is, but I guess that's good to rule stuff out.

The next steps would be throwing on the new tensioner assembly I have and possibly changing the alternator, which would be cheaper than another rebuilt supercharger.

 

I changed the alternator the following day, and the noise went away. Was able to get one locally at Advance Auto. This is the noise it was making before I changed anything.

 

That is... Weirdly similar. Makes me wonder if this is a pulley issue after all. Maybe it makes sense to try swapping them all out before the big, expensive one.

Thanks!

 

Yeah, I would try that first. I should have known better. I did the long handled screwdriver trick to isolate the noise, and it was definitely louder on the alternator than the supercharger, but thought since the alternator is attached to the supercharger and it spun smooth by hand, it had to be the SC. At least the rebuilt SC was half the price of the Rotrex SC I replaced in my old Miata last summer.

 

Finally got my answer because the problem got worse. Definitely the supercharger. It was spitting out oil from the pulley and making MUCH worse noises on Fri. Ironically, I had finally booked an appt with the dealer (I know...) and by the time I brought it there it was super obvious. Luckily they didn't even charge me because as soon as I popped the hood it was like "Well there's yer problem." Luckily the car made it home.

So now I guess I have about $2k worth of parts to buy and many hours of work to do. Might also change the alternator as well as the SC, water pump, and tensioner assembly (since I have it already). Will likely throw in a new belt again and maybe look for some gaskets, clamp, and hoses that could need a refresh while I'm in there.

Any other recommendations are appreciated. Thanks for everyone's help so far with things to look at!

 

Let me guess: You're not going to buy another rebuilt supercharger from the same place you got the last two? Right?

 

I am currently investigating options. And there aren't many, considering price and availability.

If I was keeping the car, I'd just invest the money in an upgrade. Sadly, I need to sell by the summer. So all this work is just so I have a car for the next few months, and then so I can sell it in a condition that isn't "needs substantial work, as-is" and get less than $1k for a car that is a blast to drive... When it doesn't have a broken supercharger.

 

Hey just making an update because I did eventually solve this. I got a rebuilt supercharger from Detroit Tuned and now my car runs beautifully again. Just in time to sell it...

I did end up having to get TWO superchargers though. The first one I got from them seized up immediately (didn't even make it out of the driveway) but they took it back and sent me another one right away that works properly. Just meant I got to do the work twice! Actually, 3 times, since I tried to just change the oil first. But all's well that ends well.

If I were keeping the car, I'd have gone with the Harrop upgraded supercharger that makes the water pump run independently of the SC. But that was thrice the price. Still, I somewhat regretted not going that route when I was disassembling my whole front end for the third time.

Thanks to everyone for their help. Lovely community.

 

I could write at length about my experience with Detroit Tuned rebuilt superchargers but I will not. I will say their customer service had been very good in all my dealings with them.

I currently have a ported supercharger from Stiegemeier that I have been running since September and it has been absolutely wonderful. Bob Steigemeier knows the Eaton M45 well and it shows in its performance for me.