Belt tensioner bouncing after replacing alternator pulley?

mtn-wagon

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I just replaced my alternator pulley and serpentine belt tensioner to fix a chirping sound from the belt and a pretty severely bouncing tensioner. The sound is gone and the tensioner is moving a lot less, but is still bouncing a little at idle - bout a 1/4 inch side-to-side at startup. Does settle down to about half that after warming up and when the engine revs it is steady.

Would anybody who has done this chime in on whether the tensioner still moves around a bit after replacing the alternator pulley? Seems pretty good to me but I was hoping for it to be rock solid after this R&R.

Thanks.
 

Genesis

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There should be basically no visible movement at all. Side-to-side implies a tracking problem and would *really* bother me -- did you check the bearing in that idler roller (the plastic one) and the plastic for any evidence of deformation or problems?
 

mtn-wagon

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Did not check the idler roller but it seemed OK to me before putting it on. I have a BEW engine if that makes a difference in the tensioner you're thinking of.

Think I'll pull the belt off to check the roller later today.
 

Genesis

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The idler on the tensioner (assuming we're talking new tensioner here) shouldn't be a factor, given that it's new. Check the play on the power steering and A/C compressor shafts (there shouldn't be any detectable with hand pressure and the belt off.)

I get the heebies on belts that don't track right -- they usually wind up failing on short mileage and almost-always when it's most inconvenient, even if it's just the serpentine belt (and not the timing belt which of course is much more-serious.)
 

mtn-wagon

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I hear you on the belt. Not wanting any leeway with this one.

Will do on checking power steering and AC, have a suspicion about the AC shaft..

Thank you for your replies.
 

Genesis

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Catching a failing A/C compressor before it does (and spews garbage all over the inside of the plumbing) is a lot more pleasant than *after* it does, especially if the "does" happens when you're on a nice long trip in the summertime and it's 95F out! :)

One of the uglies about a bad alternator pulley (or wrong alternator with a solid one) is that the additional shock loading it causes can trash the other bearings driven by the serpentine belt. There have been a few people here with ALHs that have reported breaking the accessory bracket where the idler bolts to, which is a *major* pain in the butt to R&R (and a bit expensive on top of it.) That doesn't look like a factor on the BEW, fortunately.
 
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mtn-wagon

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Power steering is immovable and the A/C compressor clutch has just the slightest bit of play in it. Does this mean the compressor itself is failing? Or might it be just the clutch?

Edit: Found my radiator fan is not functioning as well.
 
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Genesis

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Fix the radiator fan(s)!

As for the bearing if you can feel a slight bit of play with radial hand pressure it's worn but probably serviceable, so long as it's smooth in rotation. If you can *see* it move or there's any sort of roughness when rotated then it's done. I do not know if the rotor bearing (on which the pulley rides) is independently replaceable on these units or not.
 

mtn-wagon

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Appreciate your replies, thank you! Will be troubleshooting the radiator fan soon too - condenser appears to be working.
 

Genesis

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The usual failure on these is in the fan itself. I've gone through a couple over the years. It's a crap design with a $1 dropping resistor instead of $3 worth of a PWM controller which would throw MUCH less heat and be far more durable.
 

Genesis

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I've never replaced the entire assembly -- the "spider" holding the fan in place comes off the shroud and both come right out -- you just have to unclip the wire going to the FCM and unplug the connector first, of course.

Do check continuity on the pins after you unplug it from the FCM first, but it's odds-on you'll find the fan itself is open.
 

Genesis

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The last time I did this I bought the Autozone Dorman deal, which came with both fans and the shroud all assembled -- I needed the car back on the road *now* with the ability to handle Florida summer heat. It was also reasonably priced, although known chineesium so....

The first one (remove fan from new shroud, screw onto existing shroud, plug it in, etc) lasted about 15 minutes - literally. It burned up, complete with smoke. :)

Free lifetime replacement got immediately used of course; the second one is still in there working just fine -- that was ~3 years ago or somesuch I think? If I had changed the entire shroud out (at considerably more hassle) I would NOT have been happy. As it was it was about 20 more minutes to swap it the second time :)
 

mtn-wagon

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Could be considering something similar myself. Not looking to overdo the installation. Looks like the fans are pretty simple though.

Lifetime replacement isn't bad for that kind of part!
 

eddieleephd

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I believe that I ordered mine from Rock auto myself, can't stand spending more money than necessary, and one fan was all I needed.

I find oem part numbers and search for them on Rock first for motors and clips and such.

I did notice that Idparts had a complete assembly for $150 Including shipping.

https://www.idparts.com/dual-cooling-fan-assembly-a4-p-10375.html

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Genesis

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Advance has the single fan itself listed for $70, or the entire assembly for $160. I'll have to look at what I paid for it but I'm reasonably sure it was under $100 at the time.

The only gotcha is the fan alone only has a 1 year warranty -- the assembly is lifetime.
 

mtn-wagon

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Idparts' assembly is also lifetime warranty which is nice. May end up doing that against the chance of another part failing.

Belt chirping is back again :( Back to doing some research. Doubtful that it's a bad alternator pulley, not positive that the first one was bad but assumed that was causing the bouncing and noise. Would seem odd to me if it was the A/C clutch pulley, there's so little movement in it to be causing all the rest.
 

eddieleephd

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The chirping is what concerns me.

Chirping on the should be a roller on the backside of the belt. I would look at anything to do with it.

If a roller is going out it could cause the chirping.

Bouncing tensioner says something is giving more resistance than it should.

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eddieleephd

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I was just thinking about the idler rollers.
If any spin too freely, that's a sign of a bad one too.
They get sloppy and wobble, causing the belt to slow and releasing bouncing the tensioner.
They should all move smoothly, however, they should slow quickly and stop in a turn
If they spin fast, or have any side to side movement, I would recommend replacement

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mtn-wagon

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Alright, good point. My understanding is that the bearings on the AC clutch need replacing to correct the side to side, perhaps the pulley as well.
 

mtn-wagon

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So I'm planning to replace the A/C compressor itself since I feel confident about finding a good price on a salvage lower-mileage compressor that will do plenty well enough.. and then I can avoid doing the bearing on the pulley and get ahead of any future failure of my old compressor.

Lot of play in that A/C pulley, more than I had thought. Tensioner bounces all over the place. I don't think the alternator pulley was ever bad to begin with!
 

mtn-wagon

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We'll assume it does rotate (assuming it's supposed to)
Indeed it does. Power steering, crankshaft, alternator pulley and tensioner all seem fine, just that A/C clutch isn't.

Alternator pulley that I replaced only slipped in one direction when tested, so I'm thinking it may not have been the problem, though it still could be. At the time I hadn't yet considered or checked for another source of the issue.

Could this car be driven without refrigerant in the system? Is there a sensor that would make sure the compressor doesn't engage, or without pressure in the system (unhook the lines?) maybe it wouldn't run off it isn't charged? After evacuating the freon I'm wondering if it would run OK.
 

eddieleephd

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A/C shouldn't operate if it's not properly charged.
I would pull the plug to it to be sure until you get it serviced

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Nevada_TDI

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I am currently running P&P fans on my Jetta as they both died a while back. At 250k miles for the factory fans is a long life in my book. ;-) I believe I paid $30.00 for the salvage fans I now have.
 

mtn-wagon

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A/C shouldn't operate if it's not properly charged.
I would pull the plug to it to be sure until you get it serviced

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Thank you.

I am currently running P&P fans on my Jetta as they both died a while back. At 250k miles for the factory fans is a long life in my book. ;-) I believe I paid $30.00 for the salvage fans I now have.
Considering this as well. Compressor isn't far from that price either.
 

mtn-wagon

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Genesis, may I ask, if the fans are hard to install as a complete assembly w/ shroud, why did you order the dual fans instead of single? To get both fans in one order? Finally looked through the Bentley to find that putting the front in service position is necessary to replace the whole fan assembly, so I'm thinking of just popping out the driver's side fan.
 
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