2012 2.5 five cylinder Sportwagen noise by belt side of engine

RabbitGTI

Top Post Dawg
Joined
Jul 20, 1997
Location
Wisconsin
TDI
B4 Passat Sedan
Here is an unusual one. Some sort of intermittent clicking noise that appears at random intervals. Sounds metallic and is on the belt side of engine by alternator. The noise comes and goes. I have not checked the tensioners and pulleys. Here is what I know now. Tensioner is not flopping around and belt runs smoothly. Water pump is not leaking. AC works fine. Charge rate is 14.3 or so. I can get on a lift and start digging later this week. Sometimes the noise sounds like it's between the alternator and the cylinder head. It does not sound like a typical rotating part noise.
 

Windex

Top Post Dawg
Joined
Apr 1, 2006
Location
Cambridge
TDI
05 B5V 01E FRF
Beat tool i have for diagnosing strange noises like the one you describe is a mechanic's stethoscope.

They're available at harbor freight and most auto supply places for relatively cheap. You can use it to isolate where the noise is coming from.
 

RabbitGTI

Top Post Dawg
Joined
Jul 20, 1997
Location
Wisconsin
TDI
B4 Passat Sedan
Thanks, I've got one of those. I'll detail this once I figure it out, maybe it will help somebody else.
 

Mozambiquer

Vendor , w/Business number
Joined
Mar 21, 2015
Location
Versailles Missouri
TDI
1998 VW Jetta TDI. 1982 VW Rabbit pickup, 2001 VW Jetta TDI, 2005 VW Passat wagon TDI X3, 2001 VW golf TDI, 1980 VW rabbit pickup,
Check the alternator clutch pulley, that's a very common cause of that kind of noises.
 

1854sailor

Resident Curmudgeon
Joined
Aug 10, 2004
Location
Westerly, RI
TDI
2015 Golf SE SportWagen, 2015 Golf SE Hatch Back.
It's not a diesel, so does it even have a clutched alternator pulley?
 

oilhammer

Certified Volkswagen Nut & Vendor
Joined
Dec 11, 2001
Location
outside St Louis, MO
TDI
There are just too many to list....
I vote for alternator pulley, too.

Take the lower belt off (this drives the A/C compressor, which has a secondary belt that runs everything else). Then start the engine and see if the noise goes away. That will at least verify it is something in the accessory drive. There really isn't anything else up there to make any noise, though.

I find a lot of the 2.5L engines start to have sticky secondary belt tensioner springs, too.
 

RabbitGTI

Top Post Dawg
Joined
Jul 20, 1997
Location
Wisconsin
TDI
B4 Passat Sedan
The noise went away the day after I posted. Only a very occasional faint sound since then. I released the tension on the belts and the tensioners, pulleys and water pump seem fine. The pully on the alternator spins both ways and seems smooth. It does make a whining noise when turned counterclockwise, what is that? I did not lock the alternator shaft to test if the pully locks in only the clockwise position. Not sure of the safe way to lock the shaft. How do you do that? I also put the stethoscope on various things and heard a noise similar to what I heard coming from the alternator body. Maybe it's something in the alternator making the noise (bearing?). Will check if the alternator pully locks clockwise tomorrow.
 

Mozambiquer

Vendor , w/Business number
Joined
Mar 21, 2015
Location
Versailles Missouri
TDI
1998 VW Jetta TDI. 1982 VW Rabbit pickup, 2001 VW Jetta TDI, 2005 VW Passat wagon TDI X3, 2001 VW golf TDI, 1980 VW rabbit pickup,
The noise went away the day after I posted. Only a very occasional faint sound since then. I released the tension on the belts and the tensioners, pulleys and water pump seem fine. The pully on the alternator spins both ways and seems smooth. It does make a whining noise when turned counterclockwise, what is that? I did not lock the alternator shaft to test if the pully locks in only the clockwise position. Not sure of the safe way to lock the shaft. How do you do that? I also put the stethoscope on various things and heard a noise similar to what I heard coming from the alternator body. Maybe it's something in the alternator making the noise (bearing?). Will check if the alternator pully locks clockwise tomorrow.
That whining sound going counter clockwise would be the brushes chattering a bit as you turn it. That's normal.
I use a screw driver to stick into the front of the alternator, being careful not to damage the stator wires. I actually normally do a twisting twitch motion where I spin the alternator and then rapidly twist the pulley backwards with my hand. I've done it so many times, I can feel whether it's good or not, simply by doing that.
The screwdriver in the rotor is the more failsafe way if you haven't done it so much.
 

Windex

Top Post Dawg
Joined
Apr 1, 2006
Location
Cambridge
TDI
05 B5V 01E FRF
Contrarian opinion. I just spin the pulley back and forth. I let the inertia of the rotor cause the clutch to over-run and feel for smoothness that way.
 

RabbitGTI

Top Post Dawg
Joined
Jul 20, 1997
Location
Wisconsin
TDI
B4 Passat Sedan
Noise went away and all the tests were negative for problems. Seems to have turned into a "drive it until it breaks" situation.
 

DivineChaos

Top Post Dawg
Joined
Jul 27, 2019
Location
Minnesota
TDI
mk6 jetta sportwagen tdi
My alt clutch pully randomly makes noise. If I put my hand on the alt it gets quieter. Alternatively it could be a failing serp tensioner.
 

RabbitGTI

Top Post Dawg
Joined
Jul 20, 1997
Location
Wisconsin
TDI
B4 Passat Sedan
Thanks, I'll just keep an eye on the rotating stuff. I think it will get noisy and give me some time instead of stranding me.
 
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