Strange Engine Clonk. Idler? Water Pump? Tensionser? wtf? [With Video]

2002 325i 135k here.

So, I changed my engine and A/C belts about 2 weeks ago. Piece of cake.

Now, however, I'm noticing a "clonk". I didn't notice it until the temperature dropped a few days after the belt change (NY). Now it makes the clonk until it is nice and warmed up.

The Video

It didn't sound absolutely terrible from inside the cabin, but with the hood open it makes me want to get into the fetal position with my hands over my ears and rock back and forth.
That poor girl, the pain and agony I'm putting her through. Help me help her.

My initial guess is the tensioners? I would imagine a consistent sound if it were a shot idler, right? (Like a normal shot bearing of any sort). Could it be the water pump (no idea when or if it was ever serviced.)? I haven't a clue.

Couldn't really tell from just the quality of the vid..
If I had to guess I say check your DISA.

Simple way to confirm if it's bad > while the engine is idling - just press on the metal clip and disconnect its wiring harness, you should notice an immediate change in noise (if it's the main culprit.)

Unfortunately it was just me and myself so I couldn't get in there well.

But it's that very loud tapping sound that is of concern. The sound is not really consistent in pattern, and goes away once the car is warmed up. The car idle's fine, accelerates fine, etc. These don't really seem like DISA related issues, do they?

^
Confirm and report back.

Or, find assistance so you can get better video.

No dice on the DISA, thank you for the suggestion though.

So, like I said it was pretty loud, and here she is. The noisemaker in all her glory.

View My Video

Tinypic screws with the aspect ratio, but you can see the wobbling idler. Strangely, this goes away (at idle at least) once it's warmed up.

On a side note, I also noticed rough *driving*, at like 35+- mph. Like forward and backward roughness, not side to side. Related, or just hypersensitivity because of this current issue?

Safe to say its the idler? Maybe shot and now that its cold out the old grease causes it to stick until it gets warmed. It does go away when it's warmed up.

Originally Posted by timworx

2002 325i 135k here.

So, I changed my engine and A/C belts about 2 weeks ago. Piece of cake.

Now, however, I'm noticing a "clonk". I didn't notice it until the temperature dropped a few days after the belt change (NY). Now it makes the clonk until it is nice and warmed up.

The Video

It didn't sound absolutely terrible from inside the cabin, but with the hood open it makes me want to get into the fetal position with my hands over my ears and rock back and forth.
That poor girl, the pain and agony I'm putting her through. Help me help her.

My initial guess is the tensioners? I would imagine a consistent sound if it were a shot idler, right? (Like a normal shot bearing of any sort). Could it be the water pump (no idea when or if it was ever serviced.)? I haven't a clue.

I am assuming you didn't change the "engine" just the A/C and accessory drive belts. The wobbly pulley is the tensioner. It shouldn't wobble. If its a spring one perhaps the spring is weak or suffered when you backed it off to remove the belt. I believe new ones are hydraulic. You might want to change it. I don't recall there being any "grease" in the region of the belts. Last thing you want near drive belts is grease. They don't work when greased up.

Originally Posted by RayPooley

I am assuming you didn't change the "engine" just the A/C and accessory drive belts. The wobbly pulley is the tensioner. It shouldn't wobble. If its a spring one perhaps the spring is weak or suffered when you backed it off to remove the belt. I believe new ones are hydraulic. You might want to change it. I don't recall there being any "grease" in the region of the belts. Last thing you want near drive belts is grease. They don't work when greased up.

It seemed so odd for it to go away after the car is warmed up. I mean, it's not like worn out wheel bearings stop grinding after you've driven the car a few miles.

The the tensioner pulley uses a sealed bearing, so there is lubricant (i.e grease) in there, or else it would seize up after short. So, I'm wondering if it's a matter of cold effecting the already worn out idler, making it that much harder to turn (with much less viscous lubricant in the cold) before it warms up.

I'm off to order the pulley. I'm wondering if I should get the whole tensioner assembly after the abuse it has taken from that wobbling pulley.
EDIT: Looks like you have to buy the entire assembly for mechanical type. (Pelicanparts)

Originally Posted by timworx

It seemed so odd for it to go away after the car is warmed up. I mean, it's not like worn out wheel bearings stop grinding after you've driven the car a few miles.

The the tensioner pulley uses a sealed bearing, so there is lubricant (i.e grease) in there, or else it would seize up after short. So, I'm wondering if it's a matter of cold effecting the already worn out idler, making it that much harder to turn (with much less viscous lubricant in the cold) before it warms up.

I'm off to order the pulley. I'm wondering if I should get the whole tensioner assembly after the abuse it has taken from that wobbling pulley.

Yes. The whole tensioner assemby would be in order. Looking at the extent of the wobble no bearing that I know of could wobble like that without having suffered total collapse and if that were the case there would be bits of bearing and pulley flying everywhere. I wouldn't drive it in that condition. If it does go it could knacker your fan, radiator, hoses, water pump etc and that would be expensive. Original tensioners had preloaded springs inside them. These do fail. It is not impossible that the spring suffered some kind of damage when you compressed it to get the belts off. It has probably not been compressed for a long time. Springs do lose their spring rate after a while especially in high temperature environments. Of course all of this is based on wht I see in your video and the noise I hear. I could be wrong.

Originally Posted by RayPooley

Yes. The whole tensioner assemby would be in order. Looking at the extent of the wobble no bearing that I know of could wobble like that without having suffered total collapse and if that were the case there would be bits of bearing and pulley flying everywhere. I wouldn't drive it in that condition. If it does go it could knacker your fan, radiator, hoses, water pump etc and that would be expensive. Original tensioners had preloaded springs inside them. These do fail. It is not impossible that the spring suffered some kind of damage when you compressed it to get the belts off. It has probably not been compressed for a long time. Springs do lose their spring rate after a while especially in high temperature environments. Of course all of this is based on wht I see in your video and the noise I hear. I could be wrong.

Definitely, I would *assume* that the wobble is a mix of a shot tensioner pulley causing undue stress on the tensioner in some way, making it relieve the stress. Which would mean that the wobble isn't all in the pulley itself. I assume. Since it is on a spring and all. I would think if it were all in the bearing then it would be a horrendous sound of grinding.

I was thinking that too, possible tensioner damage during the belt change. Also, it had a SLIGHT version of this sound when cold before (I thought it was just the belt since it needed replacement, although it was more of a sound like this then a belt squeak. But not NEARLY as loud.) So maybe by tensioner pulley or assembly was on its way out and the belt change made it worse. Plus I swear it happened as soon as it got cold. Plus it goes away now when the engine is warm. Strange.

That's what is really throwing me, that it goes away when the engine is warm.

That could easily be just the pulley. Most likely your tensioner is fine. Replace it and be done before the thing does come flying off and you need a new belt and overheat your engine. No use in speculating. Plus if the tensioner is also shot you should be able to tell that there isn't good resistance when you try to relieve the pressure. In any case your pulley is def gone so order that up first. You might as well get the idler pulley too because that is probably also shot or will be soon.

Pop out the belts, spin the 3 pulleys, if there are any play, then the pulley is shot!

Problem has been solved:
While the tensioner pulley does seem as though it is due for replacement soon, it was NOT the cause of this issue.

I was going to mention the "far fetched" idea earlier that there could possibly be something on the belt, causing tension to build and release every time it goes over a pulley. But I figured people would think I was crazy.

Well, that turned out to be the problem. The cause was a sh*tty Continental belt from PelicanParts.com. I looked at it after I got it off and you can see buildup on the grooves from the manufacturing process.
Went around the corned to Advance Auto for a new one and low and behold; no more horrendous sound.

Originally Posted by timworx

Problem has been solved:
While the tensioner pulley does seem as though it is due for replacement soon, it was NOT the cause of this issue.

I was going to mention the "far fetched" idea earlier that there could possibly be something on the belt, causing tension to build and release every time it goes over a pulley. But I figured people would think I was crazy.

Well, that turned out to be the problem. The cause was a sh*tty Continental belt from PelicanParts.com. I looked at it after I got it off and you can see buildup on the grooves from the manufacturing process.
Went around the corned to Advance Auto for a new one and low and behold; no more horrendous sound.

Jeez. That sucks big time. Who the hell would suspect a new belt to behave that way? Glad you sorted it out.

Originally Posted by RayPooley

Jeez. That sucks big time. Who the hell would suspect a new belt to behave that way? Glad you sorted it out.

I certainly wouldn't! I'm glad I looked it over to notice the junk. Hard to see, but I attached an image. The groove closest to my thumb has the junk.

Lesson learned, always inspect your serpentine belts, because little imperfections make a big difference.

I'm just thankful that the violence tensioning and de-tensioning didn't damage anything.

The sound it made was just horrible.

Originally Posted by timworx

I certainly wouldn't! I'm glad I looked it over to notice the junk. Hard to see, but I attached an image. The groove closest to my thumb has the junk.

Lesson learned, always inspect your serpentine belts, because little imperfections make a big difference.

I'm just thankful that the violence tensioning and de-tensioning didn't damage anything.

The sound it made was just horrible.

Looks like crud.

Manufacturing crud, their inspector didn't look close. It's belt material, still attached to the belt itself. I started scraping it out (not easy since it's attached), but decided against wasting my time and went around the corner to Advance Auto.