Hey there guys, I have a goodie for ya. I have a 2005 VW Golf GLS 2.0 that I got pre-certified at 26,000 miles – right now I am at 57,000. The car is in immaculate condition and I’ve never had any problems with it save the control arms which were under warranty.
So, a couple weeks ago I was taking a drive at night and pulled over into a parking lot to take a look at the cool new sidemarkers I had thrown on the car to see what they looked like on at night. Lo and behold I heard a soft noise from the hood so I opened her up and heard a soft intermittent noise coming from the accessory belt/tensioner area. Here’s a quick video recording of the actual sound:
http://www…PfQt-jmP10
Anyway, the sound only happens occasionally for what seems to be no apparent reason and only happens after the car has been driven for a while, never on a cold startup. I took a 2 hour drive the other day and parked and the sound never came about, likewise with the last couple days driving to work. I think the evil little car gnomes may have vacated for a bit, but they seem to come back when I least expect it.
So, intermittent sound happenening occasionally from serpentine belt/tensioner area (could it be the water pump bearings?), only after it’s been driven for a bit. My impression of the sound is as follows if you aren’t able to view the video:
eeeoooooooooooooooooooeeeee
wait 2 seconds
eeeoooooooooooooooooooeeeee
wait 2 seconds
Thanks guys!
Was The Car’s Air Conditioner Or Defroster On At The Time Of The Recording ? Did The Intermittent Duration Of The Noise Parallel The Intermittent Engagement / Disengagement Of The A-C Compressor ?
CSA
Hi there! I hadn’t had either of those on, no. But maybe I’ll do a little test tomorrow and see if it happens when I put them on. My dial that picks defrost, fan forward, fan below, etc. has to be on something obviously, but the actual fan wasn’t running.
When You Try A-C Or Defrost, Make Sure The Fan Is On, Even At A Low Setting.
For 10 to 20 bucks you can buy an automotive stethoscope, at Sears or an Auto Parts store, and become “Dr. Motors”. They are quite sensitve to sound and can give your ears quite a jolt. The probe is ordinarily pretty long to keep you at a safe distance.
Extreme caution must be used while probing around a running engine ! Don’t have anything dangling, like clothing, jewelry, hair, etcetera, and don’t touch the stethoscope to moving parts.
I check for sources of sounds like this by touching (and even lightly pressing) the probe to whole components like the body of alternators, A-C compressors, power steering pumps, timing belt covers, and so on. You can also carefully probe a stationary nut in the center of moving pulleys on things like belt tensioners.
You can usually isolate the noisy part this way, but be careful. Compare the sounds you hear while it’s making the noise and not making the noise and from one component to another.
Have you got a white lab coat ? It’s fun to get the neighors talking when they see you working on the patient in your driveway.
CSA
Good call, I’ll see if they have one of those tomorrow at the store. I don’t have a lab coat but I do have a straight jacket, would that do? 
Tardis, That Would Do It !
CSA
Got mine for $1.99 in their store on sale.
I recall my dad’s axiom. Replace the easiest and cheapest parts first if you are going to fix by part changing. But I listened to the vid you posted, and most likely you are right to believe it is the water pump bearing. A mechanical bearing, the water pump would rumble like that, versus the simple high pitch oscillating whine of a race bearing in the act of Failing. If you want to keep this car, pay the $800 - $1100 TO replace the water pump AND the timing belt (or chain). I would go back to who I guess is an honest mechanic. Do more than less. The timing belt is housed behind the water pump, and while it is expected to last at least 80,000 milesm honestly, your car is no model for engineering or quality control excellence. Good luck.
Kizwiki, You Are Not Heeding Your Own Advice. Replacing The Water Pump As A First Guess Is Not Replacing The Easiest And Cheapest Parts First.
Although your guess could very well be accurate it only makes sense to check other components first at a very inexpensive cost $2 - $20. Why throw $800 to $1100 dollars at it first ?
CSA
Well, thankfully I believe the water pump (if I read my warranty pamphlet correctly) is under warranty, however the timing belt is not. Issue for me is if I do in fact take it to the dealership, they could rack up hours and hours of labor just waiting for the sound to happen before they can even figure out where it’s coming from because it’s so bloody random 
What is the VW recommendation (in terms of both odometer mileage and elapsed time) for changing the timing belt? If you don’t know, it is time to check the Owner’s Manual.
I do recall several posts in this forum regarding VWs that snapped their timing belts prematurely. So, if you are approaching that interval, you should probably have it changed. I assume that you are aware of the extensive and expensive engine damage that would occur if the belt was to snap.
All of that being said, timing belts do not normally give any warning of their impending demise. The noise is more likely to be coming from the A/C compressor, or the water pump bearings, or the bearings in the belt tensioner and idler pulley, or perhaps even the alternator’s bearings.
The manual says 80,000 miles actually, but if the issue is the water pump I may just ask them to do it all at once if they suggest it. Just hate the fact that the sound is only there like 25% of the time, it’s like a teaser, so I never know when it’s going to pop up or if it’s serious or not!
Yes, if the water pump is replaced, you will save a lot of money for labor costs by having the timing belt replaced at the same time–even though it will be a bit early.
Just went to the post office and I heard it start very slightly, not as loud/solid as it normally was, just little spurts when I parked. Only a 10 minute drive back and forth – I did not have my AC or defrost on. Sounded like it was just starting, very light and not as… How do I explain it. It was just more disjointed, happened in bits rather than the even every two seconds sound.
i would feel comfortable putting this noise in the “must monitor, but no need too identify just yet” file. Does every odd noise a car makes need to be explained? I have found the percentage of these type of noises that the customer demands be identified decreases quickly when it is the customer that must pay the bill.
Very understandable, kinda neat hearing a mechanic’s point of view 
What I am going to do is get one of those stethoscopes as was recommended and check it out a bit and keep an eye on it. If it gets worse naturally I’ll have to bring it in if I cannot find the problem. If it’s something that I can fix, great, if not (I don’t feel comfortable trying to replace a water pump for instance) then I will have to head to the dealership. I just hate not knowing, so I have to find out but thanks all for the ideas and thoughts, keep em coming as you have them, I’ll try and do the ‘dirty work’ thanks again!
One thing you might be able to do, if you feel comfortable doin git, is to remove the accessory drive belt that turns the water pump, and then using your hand, turn the water pump, and feel for any looseness, grindy feeling, or wiggle in the pump shaft.
If you feel any of that, then you know the bearing in the water pump is starting to go, and it is time to replace it.
If you don’t want to fully remove the belt, and you can have a friend hold the tensioner so that the belt is loose, you can do the hand test on the pump pulley that way.
BC.