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Automatic Tensioner


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When my car sits an extended period of time (overnight or longer) and it rains very heavily or is humid, my serpentine belt squeaks upon start up for probably about 1 minute worth of idle/driving and then is noise free no matter what weather condition. It has never made any sounds on a warm or cold day if it has been relatively dry out.

 

I checked the belt alignment with the pulley and to see if the pulleys had any play to them and they did not appear to. The belt also looks to be in relatively good condition with no cracks or dirt either. Based on other sources I've been reading, it sounds like it could either be the belt starting to go bad or the automatic tensioner being the slightest bit too loose from the belt stretching over time.

 

Is there a simple way to check to make sure the tensioner is in good shape? I looked in the FSM and made sure it easily loosened and tightened when turning the bolt clockwise and counter clockwise respectively. Can the tension limit be changed on an automatic tensioner?

 

The belt is the original from the car and is 3 years and 46,000 miles old. I thought modern belts typically lasted longer than this, but I was interested in others experiences. Belts are relatively cheap, but I'd rather make sure there aren't any other checks I didn't think of doing before throwing away a good belt. Thanks in advance for any input!

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If in doubt, just replace the serpentine belt. While it's off, clean all pulleys and idlers to remove any oil or coolant residue. Check carefully for any signs of oil or coolant leaks around the front of the engine. If the tensioner has failed, it should still be covered under the 5 year/60,000 mile powertrain warranty.

"If you don't know where you're going, any road will take you there." ~ The Cheshire Cat (Alice in Wonderland)

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I appreciate the feedback! I think the main thing I was curious about if there was a test to check that the tensioner is providing the proper tension to the belt. If so is there a specification other than just tight enough so that the belt does not squeak?
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... is there a specification other than just tight enough so that the belt does not squeak?

There is no published spec for the automatic belt tensioner on the 2.5 (FB25) engine. (The 3.6 H6 engine employs a manually-adjusted tensioner, which does have a published spec.)

 

Besides checking for contamination, also check that the idler pulleys turn easily and smoothly. A failing pulley bearing can cause the belt to slip and squeal.

 

FWIW, I don't think I've ever seen the spring in an automatic tensioner fail. It is typically the pivot shaft bearings or the pulley bearings that fail first, but usually well beyond the 100,000 miles-in-service mark.

Edited by ammcinnis

"If you don't know where you're going, any road will take you there." ~ The Cheshire Cat (Alice in Wonderland)

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tsb# 02-168-17

 

SERVICE INFORMATION BULLETIN

 

2013-2017MY Legacy & Outback 2.5L 2012-2016MY Impreza 2.0L 2013-2017MY Crosstrek 2011-2017MY Forester

2015-2017MY WRX

New Accessory Drive / V-Belt Availability to Address Slipping (Squeal or Chirping) Sound

NUMBER:

DATE: 06/15/17

This Service Information bulletin announces a material change to the engine accessory drive / v-belt made to address customer concerns of a slipping belt (squeal or chirping) sound.

PRODUCTION CHANGE INFORMATION:

Production change were made on the models listed below only. After confirming the condition, the remaining applicable models should be repaired with the new part number V-belt from the table below.

PART INFORMATION:

The part information below is for reference ONLY. Always refer to the Parts Catalog for the most updated information before ordering.

Continued...

02-168-17

Vehicle / Model

 

 

Part Name

OLD Part Number-NEW Part Number

V-BELT

809221200-23780AA110

809221170-23780AA120

809221210-23780AA130

23780AA010-23780AA140

809221160-23780AA160

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tsb# 02-168-17 ... 2013-2017MY Legacy & Outback 2.5L ...

I think we have a winner!

"If you don't know where you're going, any road will take you there." ~ The Cheshire Cat (Alice in Wonderland)

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I'm on my third belt....First one was replaced at 37,000 miles...No charge as the dealer didn't fix it the first time I brought it and had to bring it back five minutes after leaving...Next belt was replaced at 59,000 with new tensioner installed...Again no charge as this different dealer claimed they couldn't duplicate the constant squeak noise under acceleration...Ten minutes after I left the dealer the noise was there...I brought it back and left it running and revved it up....Needless to say the service writer was embarassed....Had the tech fix it right in the service row where I left it...At 75,000 miles with finger crossed...
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