Since a few months I have been able to hear a short and intense whistle coming form the engine bay.
Something that is striking is that the whistling doesn't occur on cold start, it only happens after a while of driving, when you turn off the engine (warm engine) and when I start it again with warm engine (randomly).
At first I thought it could be the drive belt, but the independent MINI shop told me that the noise didn't coming from that area, but came from the rear area of the engine and that it was undoubtedly a faulty PCV diaphragm. Yesterday they changed the PCV diaphragm but the whistling is still present.

From what I have read it could be:

- Drive belt
- Water pump pulley (rubber)
- Water pump
- Vacuum flexible hose leak

Any other ideas you can give me to avoid unnecesary replacements will be more than grateful.
Here a video where you can hear the noise on a warm start:


EDIT: You can hear the short whistling between seconds 00:16 - 00:17

 

Could you please make another recording, preferably without street noise, and maybe indicate the time when it appears and disappears? I hear several things, but no "whistle".

 

George, the whistle doesn't always appear, it 's random. Very difficult to diagnose and record it. I will try it again.

You can hear the short whistle between seconds 00:16 - 00:17

 

I was able to hear the noise while seeing the engine bay after I finished driving for 1 hour, turning the engine off and on again. I could see that the whistling noise occurs when the water pump pulley starts moving and/or when it stops moving. This would explain why the whistling only occurs when the engine is warm (I think that when the engine is cold the water pump is never activated).

Now I need to know if the issue is on the water pump pulley, the water pump, the belt, the tensioner or the friction wheel.

Surely I should buy all 5 and change them to avoid any diagnostic mistake.
Any advice will be appreciated.

 

After doing a deeper analysis, I was able to come to new conclusions:

Why is the whistling noise heard only when the engine is hot and on idling? That was a question I couldn't completely answer, the hot engine makes the water pump start and stop, but why only at idle and not at any time?
The difference is the speed at which the pump pulley rotates, I suspect that the problem can be heard when it rotates at idle speed but that doesn't mean that it doesn't fail all the time, but it is audible only around that speed.
Since I have found a lot of information about this issue, but with several solutions (from just changing the belt to changing the tensioner, friction wheel, water pump, pulley and belt) in all the cases I could see the water pump ALWAYS was changed (plus something else).

In my case I'm going to change (IMHO) the critical points:

- The belt (I have to change it anyway)
- The water pump (I'm sure there is something wrong with the internal bearing, surely the noise comes from there)
- The water pump pulley (it's a great opportunity to change it and also rule out that it is not a problem due to a worn rubber. I could see the condition when changing the parts).

Friction wheel and belt tensioner will not be changed on this first stage.
Replacement parts are on the way.
Indy shop appointment: 08/03

Any advice you can give me will be more than welcome.

 

Thanks for pointing out the exact time, I was able to hear it.

Regarding the friction wheel only activating the water pump when the engine is cold and idling: how did you reach that verdict? Did you remove the right front wheel and lining and looked at the friction wheel? Or do you simply base it on the fact that you can't hear the friction wheel? Did you monitor coolant temperature throughout?

The "whistlling noise" in your video does indeed sound like the friction wheel being activated/deactivated. In the case of my N16 engine, I can only hear it at idle when outside the car. At higher rpm's it is difficult to hear the friction wheel move, especially when the car is moving.

What I do find worrying in your video is that your engine seems to lose rpm's (and "smoothness") immediately after the friction wheel is heard (as if someone opened the oil cap at the same time). Is that indeed the case or just an illusion of mine?

 

I can see through the side of the engine that when I start it in the morning the friction wheel doesn't move until the engine gets warm. When the thermostat activates the friction wheel to start the water pump pulley, the noise briefly appears at that exact time (like in the video). I have started the engine and waited several minutes to verify that it is exactly when the water pump is activated that the noise appears. When I hear the noise, if I press the throttle, the noise goes away, but it comes back if I release it. When the friction wheel stops connecting with the water pump pulley, there is no longer any noise, either at idle or running

In my case, the noise is quite sharp and loud, I can hear it even with the windows closed. It could be that at high speed the noise was also present, but if I'm in neutral, with the engine idling and I start to raise the RPM slowly, the noise never appears on RPMs above idle in accel nor decel nor at a constant RPMs other than idling

Great observation, I could see the same thing every time I was watching how the water pump was activated and deactivated by the friction wheel. I don't know exactly what produces it but since I think there is an issue with the water pump, it could be that the pump is a bit blocked (could be the internal bearing), it generates the noise that I want to eliminate and it also "brakes" the entire system a little when it is activated. But it is only what I think, I hope that this behavior will go away after changing the parts.
I have been trying to reach the pulley with the engine cold, to try to move it by hand (in theory, it should move freely when it is deactivated) but I have not yet succeeded

 

This I don't understand. The noise is constantly there? In your video I only hear the noise the friction wheel assembly makes while it "moves up" (or down for that matter). There shouldn't be any noise from the friction wheel assembly while it is at either the "up" or "down" position (except possibly a high pitch whistling noise from its pulley's bearing).

This would indicate a defective friction wheel assembly (provided we are both talking about the noise the friction wheel makes when moving up or down and not noise by the water pump and/or other engine parts).

Did you monitor the coolant's temperature throughout?

I'm not sure it is possible to "push" the pulley upwards in order to manually engage the waterpump. And I don't think it would be a good idea to fiddle with wires (trying to manually apply 12V to the friction wheel assembly) so close to the running serpentine belt and pulleys.

Here is a series of video's I made while trying to find out what was causing my friction wheel assembly to rattle. In part 3 of it (linked here) you can hear what the friction wheel sounds like in my car (at 1:09). In parts 1 and 2 (linked from within the description) you can also hear what the engine sounds like without the friction wheel pulley touching the crank pulley as well as better identify the high pitch whistling noise of the pulley's bearing I referred to above.

 

No, the whisling is not constantly there. I can hear the friction wheel while it is being moving up and down (mechanical noise) by the thermostat but it is OK, no problem at all with it. The whistling noise is only with water pump engaging, disengaging or randomly while working on idle RPMs. Never with the water pump off.

I think I didn't express myself correctly and I could have generated confusion. The mechanical sound of the friction wheel when moving up or down is OK, there is no noise similar to a bearing issue.

Yes, I use Torque app to verify that the temperature drops when the water pump is engaged and while reving the engine and on idle too. Test with result OK.

I was talking about moving the water pump pulley with the engine off, not the friction wheel up or down. If it does not move easily it could be in a blocked condition (drops engine revs when engaged and generate the whistling noise).

I had already seen your videos a few weeks ago while looking for my "noise". Although the noise is different, I found them very interesting and it is very clear what the problem was and how it was solved. There I can clearly hear a metallic sound of a loose or bad bearing. Very useful to diagnose the problem and solve it easily, thank you very much for sharing it.

These days I found another video on the internet (2009) with a Cooper with exactly the same noise as mine. And it also occurs only at idle. The user interpreted it as "noise just appear while finish parking my car.". The same as I thought the first times I started to hear this noise:

 

Giorgio,

After carefully watching and listening to your 3 videos several times, I could find my noise in all 3.
Can you hear the little whistling noise too?


Video # 1
00:33 on automatic water pump disengage



Video # 2
00:12 on automatic water pump disengage
00:24 while engaging water pump manually
00:36 while engaging water pump manually
01:22 on automatic water pump disengage



Video # 3
01:20 - 01:21 on automatic water pump disengage

 

I don't remember trying to turn it by hand when working down there, but if I did and the resistance/drag were high, I think that I would have followed up on it. Also, from my videos it is visible that the waterpump continues to turn when the friction wheel disengages and that it comes to a stop quickly but relatively smoothly.

While the sound in this video did indeed open up my eyes (or rather, ears!) and helped me identify the sound in the other videos, it is my impression that the sound is a different one. The sound in your video and in mine (more about those later) come and go a bit smoother, as if air pressure is relieved. The sound in this video sounds more like a constant, mechanical sound. It reminds me of the noise slipping belts make in the cold when old.



Yes, indeed I do!(and shamefully admit that I never noticed them!)

However, at these two instances in the second video:
it is the case that the water pump is not actualy engaged at all! The framing of the video doesn't show it, but I only pushed the friction pulley so far out of the way, that it no longer touches the serpentine's outer surface. I didn't push it against the water pump pulley (if I had, the high pitch whistling noise of the friction pulley would have re-appeared almost immediately). This is a clear indication that whatever causes the whistling noise you so accurately identified is not caused by the water pump.

Unfortunately, my (almost nonexistent) wisdom ends here. I can't say what could possibly create the noise. From the sound of it, I would suspect some sort of air pressure or friction relieve that "settles" smoothly at the end.

PS.: Many thanks for your effort in guiding me to identify the noise!

Edit: striked out reasoning as it is both incorrect and misleading.

 

I'm trying to find some videos on youtube with people moving the water pump pulley manually (with other issues than a water pump problem) to check how free it should be with the engine off.
It could be that this little whistling noise is something expected but that when there is a "problem" it begins to appear at a higher level. Just maybe, I'm not sure about it really

Totally agree with you

Thanks to your videos I was able to learn that the friction wheel is always moving (I thought that when it was activated it would connect the two pulleys at the same time).
I believe there is still a chance that it is the water pump.
If the noise is caused by the water pump bearing, maybe when you moved the friction wheel to your left, it touched the water pump pulley. The friction wheel braked against the water pump pulley, and the pump "almost" moved or moved very little, and that may have caused the bearing to move (then there is a small noise).

Two more things about your videos:

I forgot to mention that when I bought the belt I avoided the continental brand thanks to your advice. So again, thanks

I could read in your videos that initially you changed these 3 parts:
- serpentine belt
- friction pulley
- waterpump pulley

Friction pulley is the friction wheel or the crankshaft pulley?

 

First up, apologies for writing in my previous message that if the friction wheel pulley would have touched the water pump pulley, the former's bearing would emit its characteristic, high pitch sound. It was early in the morning and with hindsight, it seems I wasn't yet quite awake. I have striked out that part.

I'm not sure I understand why you added the part in the parenthesis (I understand "connect" as in "transfers the spinning mostion to the water pump pulley").

In the first of the my videos it is actually visible that the freely spinning friction wheel does indeed slightly turn the water pump pulley when I pull it away from the crank pulley. Just a bit at 0:10 and more so at 0:40. At 0:40 I think I hear a short noise resembling the one you pointed out. So you may well have spotted the source of the noise! Please let us know if it does turn out to be so.

FWIW: the water pump in my car has started making a slight knocking sound when activated (similar to the knocking sound in video 2) even with the smooth serpentine belt. So it may well be that its bearing was damaged while driven with the belt residue stuck in the crank pulley. And if that is indeed so, it may also be related to the whistling noise you spotted.

So I, too, will change the water pump to be on the safe side.

Initially I changed the serpetine belt, the entire friction wheel assembly (in Europe, one can buy the friction wheel pulley separately) and the waterpump pulley (all for nothing as it turned out).

Which serpentine belt did you get?

 

I believed the friction wheel was always free and not moving while water pump is off. Now I know that the friction wheel is all the time moving, touching the crankshaft pulley, and when activated it continues moving but also touching the pump pulley.


I can't hear the whistling noise on the video #1 but I can see the water pump pulley movement clearly.


Nice, it should remove this whitling noise in both cases. I hope!


That's great because if you can detect the same "noise" before and after the entire friction wheel assembly replacement, then we know there is not the issue (whistling noise issue).


Dayco brand

 

I just listened to the original video files on my pc over high quality home Hi-Fi headphones. At 0:40 of the first video there is clearly a similar noise when the pulley is turned by about a third of a revolution from the manually lifted friction wheel. At about 1:20 of the second video it is also clear that the same noise is emitted just before the water pump pulley comes to a stop.

Also, I just noticed that I didn't mention the following in this thread:

a. the engine of my car was started from pretty much cold when I recorded these videos. At regular operating temperatures the water pump is kept activated for much longer, maybe even permanently.

b. after replacing the belt, the friction wheel assembly and the water pump pulley I also replaced the crank pulley. It was only then that the cause for the rattling friction wheel assembly (melted belt rubber within the crank pulley's tracks) came to light.

 

I checked your video #1 and I can hear the same noise that is currently on my water pump too.
Video #2 at 01:22, I could hear the noise yesterday and it's the same noise too.

I understand that your problem was more critical than the small whistling noise (which could be interpreted as normal, the same would have happened to me) compared to your original noise.
Now that you have solved it, it's more evident and you can find it much easier to fix. Surely I will have to change the friction wheel in the future, if the water pump pulley is forcing or braking it in any way while the crankshaft pulley wants to make it move (RPMs drop)

Only 2 more weeks on this side to know if everything we have said makes sense or if there is something else that we are not being able to understand :-)

 

Getting the friction wheel assembly out was far more work and trouble than getting the waterpump pulley out (and back in). Other owners had advised me to also change the waterpump pre-emptively while in there but I didn't want to mess with having the coolant removed and bleeded afterwards. With hindsight, I should have done so at the time.

According to videos on the web, both the water pump and pulley can be done on their own (i.e. without removing the fricton wheel first as described in newtis). Though it still looks like a big, royal pia. I'm also concerned about damaging the sealing surfaces both on the engine and the pump while trying to maneuver the pump out and into its spot.

I wouldn't think so. The friction wheel's bearing is very smooth and with very little resistance. The wheel itself is completely made of metal. All it does is hang in there between the other two pulleys, passing on any forces without being affected itself. So I doubt it has taken any damage. At least mine didn't, despite the "knocking" by the crank pulley over a period of a few months.

Please keep us posted!

 

I have not received the parts yet due to a shipping problem.
I bought the pump and pulley from ECS Tuning but for some reason UPS returned the package to the seller once it reached the destination.
I'm trying to contact ECS since last week but I cannot get my messages answered...

 

I received the parts just today
Now I'm making an appointment with the indy shop, surely they will be able to take the MINI in 2 weeks.

An additional detail to update is that the noise is now louder and more frequent.
When the water pump is running and the engine is idling, the noise is always there without exceptions.

 

Sorry for the delay, glad you got them.

 

no problem, sales team was very kind.
Thank you for your comment

 

Car is at Indy Shop right now for water pump, water pump pulley and multi-rib belt change.

If everything goes OK, surely it will be ready today.

As I had already mentioned, the noise was now constant so I will know if that fixed the issue when I returned to home.
I want to know the old water pump status too.

 

All 3 parts were replaced without problems.
The old parts seems to be in complete "good" condition, then I have no an exact evidence about the noise origin with the old parts on my hands.

Now there is not any noise at all on engine idle nor running on any RPM range nor when the water pump is being engaged, disengaged or fully working.

I will wait some weeks to confirm the issue was totally fixed.
I will be checking too if the RMPs drops when the new water pump is being engaged as with the old water pump to check if that behiavour was related to the defective water pump too.

I will let you know soon

 

More than 3 weeks later:

- No noises at all
- No RPMs drop when water pump is being engaged
- Coolant temperature as expected on city/highway

 

Excellent! Thanks for reporting back!