Serpentine Belt Replacement - Subaru Outback - Subaru Outback Forums
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post #1 of 58 (permalink) Old 12-05-2008, 07:05 AM Thread Starter
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Serpentine Belt Replacement

This is one of the easier things to do as far as car maintenance, if you can change your own oil you're probably competent enough to do a belt too.

Inspect or replace your belts every 60,000 miles so says the Manual.

At 95,000 miles realize you have factory belts and they're cracked, torn, frayed, and you could spare the 20$ to replace them.

There are 2 belts on the EJ25, one for the power steering and alternator, and a seperate one dedicated to the air conditioning. I decided to replace both because, why not? It may not be time, but its 10$ and I dont have to worry about it.

Parts required:

12MM socket
10MM socket
Socket Wrench

The belts, obviously.

Step 1: Park it, Pop the hood, disconnect the battery, marvel at your 2500CC engine and blah blah.

Step 2: Undo the cover for the belts, it goes between 10mm and 12mm. Extension may be required here. I'd also like to add, the bolt that holds the cover on, do not remove all the way, as it also holds the alternator in place and there is a small bracket it attaches to at the back of the alternator, that is held in place only with that bolt.

Step 3: 12mm Bolt to Undo the alternator, which acts as a tensioner on the first belt. Its on the left side of the alternator and you can see a long bolt and where the alternator can move. When you're done undoing it you should be able to simply slide the belt off. I only had to undo the alternator about 2/3rds of the way down its path to remove the belt.

Step 4: Second belt time! Still using the 12, look down on the belt and you'll see the tensioner pulley. Loosen that, but don't remove it, Then switch to the bolt that pulls the pulley up on the slide. Make sure it is loose before undoing the long bolt, otherwise you could snap it. Simply undo it all the way, and you should be able to remove the AC belt.

Step 5: Put the new belt on, it should slide over. Slide it over the tensioner last. Tighten the tensioner pulley to roughly where it was, you want it tight enough to where it doesn't slip but not so tight that it is putting stress on the system. I go by the grime on the threads of the bolt, then adjust from there. The belt shouldn't be able to deflect more than half an inch or so.

(pic is labelled to help identify parts.)

Step 6: Do the same thing with the Alternator pulley, put the belt over the alt last, and tighten her up.

Step 7: Put everything back together, inspect the belts to make sure they're all lined up. Turn on the engine, make sure the belts don't screech and they turn nicely. Make sure to check the power steering by rotating the steering wheel on a lock to lock, and cycling the A/C compressor.

Enjoy your new belts and peace of mind!


This process is also very similar on every car I've ever seen. Some have different methods of tensioning the belt, but its all pretty straight forward if you look at it. Don't tell your family that you did this, they'll swindle you into doing it instead of their mechanic and then they won't pay you.
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post #2 of 58 (permalink) Old 12-05-2008, 10:28 AM
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I yearn for the time when motor sports were dangerous and sex was safe

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post #3 of 58 (permalink) Old 06-28-2009, 06:05 PM
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Muchos gracias! Excellent DIY write-up with pics. I'll put this in the glovebox in case I'm stranded and need it. Would save a lot of time pondering.
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post #4 of 58 (permalink) Old 06-28-2009, 11:52 PM
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nice. is that a dryer vent for your air intake? awesome
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post #5 of 58 (permalink) Old 06-29-2009, 11:45 PM Thread Starter
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Yes it is. It worked great however I have since removed it. I dont have a fender liner and it was sucking from the fender and my filter was shot at <4000 miles.
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post #6 of 58 (permalink) Old 07-06-2009, 08:20 PM
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Sepentine belt replacement issue

Thanks for the pictures. I had no problem with the alternator but as I was loosening the tensioner pulley guide bolt (long bolt) it broke the plastic piece at the bottom that it fits into. Do I need to replace the whole assembly now or is this just an insert that should be a cheap fix. I inspected the bolt after I took it out (it was just dangling there) and it was not straight at the bottom (I guess the cause for the breakage.)

Any ideas or help? I still need to change the smaller belt but didn't loosen the pulley after this piece broke.

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post #7 of 58 (permalink) Old 07-06-2009, 08:23 PM Thread Starter
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You broke what the piece that attaches the pulley to the bolt? Thats metal. I'm not exactly sure what you broke. Could you perhaps grab a picture and post it here?
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post #8 of 58 (permalink) Old 07-06-2009, 08:30 PM
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No - it was definitely plastic and the piece the long vertical bolt beside the idler pulley slide. I will try to post picture tomorrow.
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post #9 of 58 (permalink) Old 07-20-2009, 09:22 AM
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I broke the same part on my previous car (2000 Forester). It seems like you skipped step 4. you need to loosen the idler pulleys lock nut in the slider before trying to turn the long adjusting bolt. I think you can run the car with no problems (other than hot humid weather with no A/C) as long as the screw is not in place. On the positive side your HP will increase

Here is the post I made couple years ago
Some people explained how you can change that part. I drove my car with that part broken for couple days until the part arrived. I used tie wraps to hold the screw in place so that it wouldn't damage the belts while the car is running.

the broken part is around $7. I bought it from this site
it's item number 5 in the picture.
if the bolt is bent you might want to replace that as well.

btw- great tutorial Brucey.
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post #10 of 58 (permalink) Old 10-17-2009, 09:49 AM
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Nice write up, these are not really serpintine belts, but more like normal fan, alternator, AC belts.

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