Engine makes a grinding/ squeaking noise from the belt tensioner when I put in drive. See video. Still noise when in park but much less. Not knowing it’s origin I just started replacing things I though it could be. Have replaced: Belt, belt tensioner, timing chain tensioner, engine mounts, AC compressor. Suggestions Please.https://youtube.com/shorts/ctDbP8otYHk?

 

I can't say for sure from listening/viewing your video but from my limited and novice experience - it may sound like your idler pulley.
Mine began to squeak and shortly thereafter began to squeal and sounded as if I had a second supercharger before it finally detonated and left me stranded with a shredded belt and a twisted belt tensioner.

I can't say for sure that it's your idler pulley. Although that's one component that seems to be missing from your list of replaced parts.
You could spray some lightly soapy water around the belt driven pulleys and see if the squeak/rattle goes away in an effort to pinpoint the source..
You might also remove the belt and give it a spin to see if there is evidence of missing ball bearings or makes noise.

Just a thought.

 

That's a lot of squeaking / squealing / chirping and the tensioner pulley looks like it's bouncing a lot. Given it's new would bet one of the other pulleys - idler, alternator or crank is going out. Would pull the belt and right side wheel well liner and give each pulley a shake and spin. Should spin freely, no grinding / binding, tight to the block and very little to no axial / end play. Everything nice and smooth. Also verify the belt is the correct size, given the stress it's been under might even get a new one once you correct the problem.

As @Here2Go says idler is definitely a common one on this and other BMW products. So is alternator especially if this one's a cheapie replacement from a previous owner.

Worst of all if you have not heard already the factory crank pulleys were woefully underdesigned and eventually separate into two halves, like a bagel, along the internal vulcanized rubber. Belt squealing / chatter can be one of the first (and last) symptoms. Would pay careful attention to it and plan on replacement sooner rather than later. Welcome and good luck. Please let us know how it turns out; we all learn from each other's epic screw-ups 'adventures' driving and wrenching on these cars.

 

I have a similar problem, though not quite as severe. My problem is EVERYTHING is new. Crank pulley, supercharger pulley, tensioner, idler pulley, alternator, A/C compressor, serpentine belt, and timing chain assembly. To me, the belt wear marks look worse than expected after 4k miles, so I think something's up - I just need to take some time and pinpoint it. :(

 

You have replaced everything and still issues? Wonder could there be some issue with the transmission. My noise Rattle gets a lot worse when I put it in gear.

Replacing idler and crank pulley this weekend. Only thing left is supercharger pulley and I think that is a real pain to get to, right?

 

@Akie-blah - I hope you went for an ATI or PRW fluid filled harmonic balancer for replacing your stock crank (harmonic balancer) pulley. Either one is a great and worry free investment - unlike the factory/OEM's which are prone to continuous (guaranteed ) failure.
Take it from @Daftlad - I believe it's just one of many of his favorite parts on a Mini.

Unless it's slipping/loose - Changing out the Super Charger pulley will probably not negate your noise. If you suspect noise maybe coming from the SC; it would be likely there is an internal problem with the SC (I would suspect).
The super charger pulley is probably the easiest (IMO) to get to but will require unbolting the top right engine mount, the lower engine mount (aka: "dog bone") and jacking up the right side of the engine about 3", so you can get a socket on the bolt. You'll also need the special super charger pulley puller tool if your SC pulley is stock. In addition you will also need a vice chain (or improvised way) to hold/prevent the pulley from spinning as you back out the center bolt.
I will say; there is a 50/50 chance you may damage the stock pulley (if it's really stuck) in the process of removal. So I would be prepared to purchase a 15% ,16% or 17% reduction pulley and belt combo. Not only if in the unfortunate event that you damage the stock pulley but you will be amazed at the performance gains replacing/upgrading it with any of the aforementioned reduction pulleys.

Just another thought.

 

To second or third what these guys say. If you don’t have the belt tool, get one. Lock the tensioner up and put the pin in the grenade.

then take belt off and start spinning things by hand. New doesn’t necessarily mean good anymore.

also paint a line across the belt back so you can watch it more easily while running and see if one of the pulleys is out of alignment.


but OP, you have to have something failed or a pulley out of round for it to jump around that severely.

 

Yes. My personal favorite. Let's see - grossly underengineered, 100% failure rate, little to no warning, instant limp mode and a guaranteed ride home on a AAA flatbed. No recall of course. What more could you want from a BMW product?

At 50K miles on a SoCal car:

 

I would use those exact words to describe the GM France sourced 4 speed auto on e34 5series. it’s a derivative of the th180, aka 3L30 from the Chevette, which the frogs grafted an OD on the back of…. Max Torque rating is 180 lbft on an engine delivering 184 lbft in a 4,000lb car.
And the BMW recommendation to never change the fluid or service it amd massive push back from dealers to not do it… used to find slews of e34s (and Isuzu rodeos amd Honda passports that used it ) in the junkyards right between 145 and 155k, all in good to great condition with a popped autotragic that cost twice as much to fix as the cars were worth.


all that to say ; beautiful description in its brevity accuracy and emotive expression.

 

a phrase which should never be used, anywhere at any time, in any context of sourcing mature automotive technology.

ahh yes, the timeless Munich lie, 'Lifetime Maintenance-Free® - it just never gets old does it? At least not to them...

 

Yeah, everything is new. OE stuff, except I got the ATI super damper crank pulley in OEM/standard size and cravenspeed 15% pulley with associated length belt as a kit from Outmotoring.

I've been really busy so I haven't had much chance to look into it. Mine squeaks a lot like yours, but my tensioner doesn't jump around nearly as much and mine is a manual so it's only ever in neutral when it's idling. At some point when I have some free time, I'll remove the belt and test everything independently but the noise is definitely coming from the serpentine belt area.