Well since it's been down in the teens here in Michigan my car has been making a weird noise upon start up. Normally on a cold start it would have a very annoying squeal but it would go away after 20 seconds. I thought maybe it's the belt making noise, but the belt was replaced when I had a new timing set installed. Now as of last night when I got out of work I started it up let it run for 5 minuets before leaving work and it didn't make a noise till I was under acceleration and it got louder as RPMs went up then it just went away. The noise stayed away for 5 or 6 miles until I came to a stop sign and stopped that's when the noise come back and the noise got louder all the way through 3rd gear then it went away it did that off and on until I got home. My question is is this a belt or other issue? When I got home I popped the hood and I could hear a faint sleek down by the alternator and whatever pulley is by the alternator. Is the a common noise for a failing alternator or could this be a failing idler pully of sorts? Any input would be helpful thank you.

2011 MCS

 

Did they replace the belt tensioner? That's usually the first thing to give trouble. Check and make sure it's turning freely. Look at the belt for skid/scorch marks.

 

Yes, check that first.

https://www.northamericanmotoring.co...e-to-time.html

 

So pull the belt off and spin the tensioner pully aND if it squeaks or feel like seized bearing replace. Can just the pully be replaced or does the whole assembly need to be replaced?

 

Whole thing. It's in that link above.

 

Finally got around to fixing it since it got worse. Well it's not the tensioner. And I can't tell what it is. I hope it's not the actual pump cuz I don't Wana spend 700 bucks. :(

 

Hope it's not the ac pump is what I meant to say.

 

This is the link to the noise at idle.

 

loosen tensioner on belt (note this is a pain in the *** on mini) turn each accessory individually to look for loose squeaky one.

 

I spun the acc pump pully and didn't hear anything, didn't think about doing it to the alternator (don't know why). Is there a way to spin the friction wheel without taking it off the block?

 

Does it sound like this?? If it does then you need a new cylinder head cover. The video is of my 2012 R56.

CYLINDER HEAD COVER:111020
LOCKING BOW:119500

 

No, it didn't sound like that. Come to find out after talking to the place that did the timing chain they installed the wrong size belt by accident. So far with the shorter belt I haven't had the noise. So far so good!

 

Awesome! Glad you are all fixed up.

 

But now that's gone I hear a strange taping nosing at idle. Not a lifter noise, so hoping it's somthing stupid and not bad. Got to love cars haha

 

You might want to have them recheck your chain tensioner and make sure it is fully seated. If it didn't extend or seat properly it could be causing a slight tapping noise from the chain and then once you're under load it advances and the chain may lose some of the slack.

Sometimes fuel injectors can get noisy especially with environmental temperature differences and/or age. If you have been listening out for any noises coming from your engine it might seem more pronounced now than it has in the past.

Also, If you have been doing anything around the intake hoses when you've been doing this work you could also have an resonator chamber that isn't fully seated. It will enhance the sound coming from the engine. I know this from personal experience.