Basically my MINI has been making a rough, semi-diesel(ish) sound. It just started all of a sudden one day on my way home from work, I heard it upon arriving. No CELs, no codes stored, no idea where to begin.

So I completely removed the front end, including the radiator fan mount, to give me enough room to do all this work:

• New ATI Super Dampener Crank pulley
• New Coolant Temp Sensor
• New Coolant Reservoir
• New Valeo SMF Clutch Kit
• Power Flex Bushings around
• Drained oil
• Drained coolant
• New NGK plugs
• Replaced serpentine belt
• New oil & filter
• Replaced timing chain tensioner
• Replaced oil in supercharger (both ends)
• Removed and cleaned MAP sensor
• Removed and cleaned intake manifold
• Cleaned throttle body
• New DT BPV
• Replaced the o-rings on the water pump intake boot

I've done a lot of this work over the course of several months. I guess since the noise started I've driven about 2,000 miles, roughly.

​​​​After changing the timing chain tensioner I thought the noise became a little less prevalent, maybe it was a placebo? Anyway there are no longer any yo-yos, and now a much smoother idle. Keep in mind the noise is always there, cold start, idle, and even after a long drive.

So, here's the noise!

 

Subscribed. I wish I could help. Sounds like something broke and is rattling around, though.

 

Where's the rattle coming from? Is it rattle ongoing or when you go over bumps? (NEVER MIND My question) You're showing a video of car sitting still and rattle coming from engine running..

 

Get yourself a stethoscope. It would make for an easier time finding the source.

 

It's around the front right side of the engine. I can't even pinpoint the location of it because the belt and all the pulleys in the area.

But based on the above video, there's nothing that sounds like a distinguished fault?

P.S. I remember revving the engine high as I started around a tight turn and quickly let off the accelarater, then I heard a high pitched squeaking/grinding noise. Like as if you were using an orbital polisher and held it causing it to stop rotating... I guess?

I've heard when alternators pulley bearings begin to fail they'll emit a high pitched squeaking? Also when a timing chain assembly fails it will spin around the main bearing, causing a similar noise?

See, this where I'm lost and having trouble pinpointing the noise, any thoughts on that?

​​​​​​​Guessing a stethoscope will be the best approach. But I hate to drive it and not know what's going on inside...😵

 

sounds like a bearing, unhook the belt start car and see if there's any noise (do not run more than a few seconds, no cooling!) , check alternator and supercharger bearing for feel/looseness

 

Has anyone noticed how slow the SuperCharger pulley is rotating relative to the engine RPM's. Is it just me, is it an illusion? I'm being serious...

 

could be the crank damper, they will split and still kinda spin while slipping, makes similar noise. Mine looked fine the only way I was able to figure it out si putting a prybar on the pulley I saw it was loose and had been slipping

if it was the crank damper you would see boost loss too though, mine would not make boost over 3000 rpm

 

Could it be something as simple as the belt tensioner and/or idler pulley?

 

If it were just belt tensioner wouldn't you see belt slapping around? It sounds internal to me. I think Mega72 is onto it.

 

O.P. stated that he just installed a new ATI Super Dampener Crank pulley...

FWIW, as mega72 states, I agree; it does seem to have an "internal" sound to it... I also agree with his suggestion to remove the belt and run the engine (cold, not already up to temp) for a minute or so to see if the sound still exists.

 

I installed a brand new ATI 2% Super Dampener. I highly doubt that's failed already. As far as power and boost go, everything seems fine after 3k RPM, basically the opposite of what you had. I've already been down that path. 😣

Edit: Everything seems fine up to 2.5k RPM and 3.5k RPM. There's a noticeable drop in power in that area it seems. Unless I've grown used to the cars illustrious "yo-yo" effect.🤔

 

Yep, I agree. Sounds internal. I believe mega72 is the closest yet! So I'll pickup a stethoscope by the weekend. Check it out then with no belt and let you guys know my findings.

Thanks all! Hopefully we can crack this mystery wide open before the week is over! 👊👊

 

It's an illusion, trust me, when I was recording the video and thought "WTF"? Then checked it out and it was actually spinning normal. Guess the camera is into playing tricks on people, not the first time. 😜

 

Now that you pointed it out, yes...
Does it appear like that to the eye, or is this just a video phenomenon?

If that's how it is in reality, then I'd say your supercharger is shot.

-------
EDIT: Just saw your post above...

 

Sorry - I was only referring to the internal post. My initial thought was some kind of bearing/journal. Seems like it's coming more from the block so I was thinking a crank issue, but I don't know enough about it to offer advice. All that to just second Mega72's input on internal.

 

Andrew says that it doesn't look that way in person. When I look at it compared to the Crank Pulley, it looks like it going in slow motion. Looks to me like the SC pulley is going slow and that the belt may be slipping, thus the reason the Crank Pulley is going at normal speed. If this is the case, it would account for all that grinding noise. Andrew you should remove the serpentine belt and start the car to see if the noise persists, then take it from there.

 

Sounds like the noise my supercharger was making before it kicked the bucket. Are you able to feel the vibration on the passenger side SC air horn?

 

OH NO! That's bad... I can feel a vibration on that side yes, and it's been significant ever since I put the Power Flex Bushings on the dog bone, but never got around to replacing my passenger side motor mount (the top one).

So, I filled my SC with oil back in April I believe, serviced all the o-rings, seals, etc. I hope it's not my SC ��.

UPDATE! Today driving home in a hurry, I noticed that when I would hit 5k RPM and shift I could hear a rattle/grinding/chain slipping on a gear kind of sound... Did it 3 times, 2 on purpose, and everytime the RPM hit 5k it would make the noise. ��

Also, the rough idles are back. ��

Edit: Oh you wait, this weekend I'm dipping into the front end of the car, removing the belt, taking a stethoscope to it, sticking a finger up it's pipe, and everything I can to narrow this down! I hope my cars not dying... Dang.

 

yeah not good either supercharger failing or crank damper is slipping, who installed the crank damper?

 

I agree the SC most likely being the source of that noise. The tone sounds just about right for something like the SC with a light alloy housing and alloy screws/vanes. Engine internal bottom end problem will have deeper tone.

 

I installed the crank damper, followed instructions fwiw.

Oh, man. The majority of post point to SC, not good. How do I really test the SC? What would cause a premature SC failure? It's always had oil. Also it's still producing the same amount of boost, would a bad unit do the same?

 

Mine was making a similar rattling noise for about 30,000 miles before it failed.


Had plenty of power it's whole life and the noise got extremely loud about 10 miles before it kicked the bucket. As soon as the noise stopped the water temp gauge pegged to the left and the red coolant light started flashing since the water-pump was no longer being turned by the SC.


Have you tried running the motor with the belt removed to see if the noise is still there?


Here is link to an older thread I started and at the end is a link to the video I took of my SC failing.


https://www.northamericanmotoring.co...-question.html


Good luck !

 

I installed the crank damper, followed instructions fwiw.

Oh, man. The majority of post point to SC, not good. How do I really test the SC? What would cause a premature SC failure? It's always had oil. Also it's still producing the same amount of boost, would a bad unit do the same?

Edit: I've had trouble with the car intake temps being 20-30°F over the ambient temperature, which seems high, unless that range is common with the Alta CAI?

 

SC gears just wear out with mileage, some last 50,000 miles and others can go 130,000 or more.