All Wheel Drive Auto: Independent Seattle Subaru Service


Subaru Timing Belt Tensioner Failure

Subaru Timing Belt Tensioner


Below are a couple of pictures of a failed Timing belt idler we recently replaced, because it came out of a Subaru with a manual transmission there is a belt guide just above the crankshaft sprocket that prevented the belt from coming off, so this driver was very lucky, had it been an automatic model the belt would have come off causing valve damage.  I will add that we do still see Subaru Manual transmission equipped cars with the belt guide still jump time, there is just less of a chance it happens

If you have read enough of the articles and posts on this website, you will find one of the things I really try to drive home is that when its time to replace the timing belt, make sure its done completely!

The belt is just a piece of rubber, The service interval on most Subaru models is 105,000 miles this is to one prevent it from breaking costing you thousands, and two to replace a “stretched timing belt”.

In the maintenance booklet it will state to replace the timing belt, so it sounds like the only thing you need to do is to replace the belt right?     Not so fast, in the Subaru Service manual it states replace the timing belt, and INSPECT the timing components.   Once the timing components have been inspected there are few ways to proceed.  Most likely the  timing belt tensioner, timing belt idlers and the water pump (which are all part of the mechanical timing system on your Subaru) are still just as old as the Timing belt, if you don’t replace them now when its all apart then when?  Even if they appear to be ok at this time, what about in another couple of years when you are on that “Road Trip” is that a good time to replace the components?  The problem is that seldom will you from the drivers seat be able to audibly depict the increase in engine noise as one of the Timing belt idler bearings starts to make more noise just prior to seizing, or hear the occasional timing “belt slap” as the tensioner can now longer keep the timing belt tight under heavy acceleration just prior to the belt jumping a few teeth.

The problem here is that either one of these scenarios are going to cost in the thousands if they occur.  I will be the first to tell you that in some cases I have seen the components go 200k before one failed, but I can also tell you that we have replaced engines on cars at 110k because the same thing occurred.  At either mileage the costs are debilitating, and for some they will  have to move on from what was a great car the just day before.


I say this all the time but if car makers really let you know how much it costs to own a car you might never buy one.!

As a small business owner, I truly understand the need to try and be frugal, but part of being  frugal is understanding the possible ramifications on taking the less expensive route.  If you Get a full detailed estimate for everything from a Subaru Dealer, and then from us obtain an apple to apple comparison, you will find that we can save you  about 20%.  That should echo in all areas of this country, so if you want to save some money find a good Independent Subaru Repair shop like All Wheel Drive Auto but don’t skimp on the repair to save even more,  even if you avoid catastrophe, you will still be paying labor twice to do something that could have been paid for once.

Sometimes shops and especially the Dealer don’t take the time to try and explain why.  Someone calls and asks for how much to replace the timing belt, the answer includes the belt and the labor as shops are to afraid of having a higher price than who you called last to get you in the door.



Failed Subaru Timing Belt Tensioner
Failed Subaru Timing Belt Tensioner
Subaru Timing Belt Tensioner
Subaru Timing Belt Tensioner


The tensioner first lost its hydraulic fluid as the seal failed, then starting bouncing on the tensioner bracket which is the notch worn into the housing.


Thanks for reading



Your Independent Subaru Expert


59 Responses

  1. Justin,

    I have an automatic 2012 forester with 72k miles. I got it in 2021 with 49k on it. I know they say to replace the belt every 100k miles or seven years. Is this something I need to be worried about?

    1. Hello Joise,

      In 2011 for the Forester model Subaru began using the FB series engine and as such the 2012 Forester uses a Timing chain and there is no mileage or time recommendation. The vehicle still has accessory drive belts that should be inspected at every service (major and minor) and replaced as needed.

      Thanks and hopes that helps


  2. So I have a 2012 forester and Ive been telling everyone that my cars been making a rattling noise while driving so I did what they suggested and did an oil change and then put premium gas in it and the noise stopped then today as I was driving my serpentine belt came loose and now I have it sitting so I can replace the belt. What would make the belt slip and what do u think I should be checking for??? The noise it was making was notice between 2 and 3 rpms??

    1. Hello Riah,

      That era Subaru tends to have idler pulley issues along with the Serpentine belt, not sure if that’s the noise you had but that’s what is typical.

      Sorry for the delay in responding


  3. Great Advice for people with Subaru’s
    I have a 2003 XS Subaru.
    I need to replace Head caskets & replace withTiming Belt Kit.
    I will replace Timing Belt Tensioner & replace water pump.
    Thank you for the tip……to not run the engine low on oil.
    Are there any other things I need to do.
    The engine has done 383.500klms

  4. An update, I was emailed photos, the 3 bolts that hold the tensioner bracket have snapped, the new tensioner is still bolted to the bracket. Any ideas on what would cause 3 bolts that hold the tensioner bracket to snap? That would seem to take a lot of force.

    1. Hi John,

      It’s really difficult to put that scenario together.

      Ive never seen a situation where all three of the tensioner bracket bolts have snapped.

      Never, and I have seen some strange occurrences through the years.


  5. Hi, I bought a 2006 Subaru Outback Ltd wagon, automatic, 180K miles. Had a local Mechanic replace timing belt, tensioner, idler pulley, water pump, thermostat, new radiator hoses (Continental Timing Belt Kit). Car was driven about 500 miles, started making a racket. Car was towed to a mechanic, who says 3 bolts holding tensioner broke (and the thread holes are oval shaped now). (says he doesnt think the timing belt skipped) Is it possible the valves are still good? The, car makes quite a noise when running now.
    FWIW, The original mechanic (works out of a Shell station) gave a warranty

  6. On my 05 Legacy GT, a mechanic recently replaced my timing belt and related components with a Gates timing belt kit. He said that the kit did not have a new timing belt tensioner bolt, so he put the old bolt in and torqued it to factory specs. Less than two weeks later that bolt snapped and the tensioner failed. There are bent valves now. He says that he is not responsible, since the cause of the problem was the old bolt snapping off. I think he should have ordered a new bolt before installing the new tensioner, and since he did not, then he is responsible. What’s your opinion?

    1. Hi Mel,

      Sorry to hear about the issue.

      1. The Gates kit should not have been used, they do not supply parts to Subaru.
      2. Your guy should have stopped and gotten a new bolt, if he supplied the parts or let you if you did.
      3. If you supplied the parts this highlights why you should never ever try and save money by supplying your own parts.

      If he supplied the parts this is 100% on him.

      If you supplied the parts you are in a rough spot.


  7. Justin,

    I just purchased a 2006 Subaru Outback 3.0 R L.L. Bean Edition with 95,500 miles on it from a Ford dealer (it was a trade in). It is the 6 cylinder version as I am sure you know. I do not know who the previous owners are so can not ask them if they did the timing chain / belt – water pump fix. In one of your posts above I believe you mentioned the 6 cylinder engine uses a chain not a belt? I plan to take it to a Subaru dealer (I’m on the East Coast) for a multi-point “once over” … would they be able to tell if that type of work had been done? Obviously not the guts of the work but be able to tell if a newer water pump is on the engine or not?

    I welcome your feedback …


    1. HI Scott,

      The H6 uses a chain with out a replacement interval, and you would not be able to tell by looking if it has ever been replaced.

      The water pump is also behind the aluminum cover and driven by a chain.


  8. Hi Justin, I’ve just found this page, It looks great, will definitely return !

    We have a Feb 2010 diesel Outback, just gone 100,000km and sent to our local mechanic down the street for the service. He’s done several before and other cars for us, knows his stuff and does it well with a smile.

    Expected a big $ bill, but it wasn’t, they said the diesel has a timing chain, not a belt so doesn’t need servicing, and that they checked with our nearest dealer 50km away who they say said the same thing.

    Should we be worried about anything else ?

    1. Hi David,

      As you may know they have never allowed the Forester diesel into the U.S., as such I have only seen one, and can’t really speak much to what’s typical to the model in terms of issues.

      I do know it has a timing chain and that I am jealous that you have one and I cant.


      1. Thanks Justin,

        I should have told you that we are in South Australia !

        I’m happy with the 6 speed manual, but my lovely wife would rather have an auto, maybe when we eventually get a new one !


  9. Hi Justin,
    I have an ’08 forester, 105k km (canada). On first drive of the day it makes a squeel noise that peaks in volume around 3000 rpm. Noise gets quieter until after 20 minutes the noise is no more. Took it to shop once but of course she was as quiet as a mouse when the mech put his head under to have a look. Next time will leave there overnight. Sound like a belt tensioner adjust needed? Original timing belt.

    1. Hi Richard,

      The timing belt tensioner is self adjusting. It would be very unusual for the timing belt to ever squeal as its cogged. Also the belt would most likely make noise for a little bit just prior to failing, so lets hope that’s not the case.

      I would guess its one of the drive belts instead or something else entirely, and yes most likely to duplicate the noise they would have to have it over night.


  10. Justin,
    My daughter (original owner) just blew the timing belt on her 2007 Forester (2.5L, manual) while on the expressway! The vehicle has only 75K miles! Have you encountered this type of failure? If so, how frequently?I’m not yet aware of the root cause… I doubt the dealer would honor any warranty (5yr/60K) and I don’t see any recall notices or service bulletins either. Should not have failed under any circumstance!

    1. Hi Ed,

      No that’s not common and sounds very frustrating. Until you know what caused the belt to fail, there is no way of knowing who to be upset with. I will say this however we see a lot of 2005 and newer models where the owner has allowed the car to run low on oil, have a camshaft seize into the cylinder head and then the timing belt breaks. If I was a “betting man”, I would guess thats the case here as well. We just made this same repair on a 2012 when the driver went 11k without changing or checking the oil

      Did you check the oil?

      If it has good service records Subaru may help, if however the failure was not a defective component but Owner error they most likely will not.


  11. I am considering a 2002 subaru forester with 140K miles. Test drive and personal inspection went smooth except.. (there is always an “except”.. when accelerating. Not regular acceleration but flooring it, I can hear a squeal. Timing belt has been replaced. Thoughts?

    1. Hello Andrea,

      Some Subaru’s will experience a high pitched whistle from the exhaust when under heavy acceleration. This is usually from the Muffler drain hole and a combination of the exhaust “rotting out” or degrading of the baffles over time. That’s just a guess without hearing it, but its common.


  12. Hi Justin,

    My 2002 2.5L Outback wagon is due for a timing belt change (100K miles) and I’ll replace the pulleys, tensioner and water pump (although it doesn’t leak and looks fine). I plan on using Subaru parts but not sure if my original water pump has a cast iron or stamped steel impeller. I heard that the cast impeller is more efficient but that the Subaru OEM replacement water pump for my car is now stamped impeller (supposedly Subaru made the switch from cast to stamped version at some point). Which version do you think is better for my 2.5L or does it matter?

    1. Hi Peter,

      So technically speaking the Stamped pump is actually considered to be the updated pump. I have never really seen an advantage either way. Many consider the cast to be better and I cant fault them for that, but the cast pump can be hard to get.

      If your car was at our shop or if you buy the parts from us most, the stamped pump is what we would currently supply.


  13. I have a an experience to note here. one year ago when I started the Subaru I heard a whining sound and after a few seconds it went away. while on the road I heard the same noise and before I could stop the car it the engine stopped and on inspection I saw the belt was out.

    on opening one idler pulley had seized. I replace the belt plus the pulley.
    last month I heard the same noise and decided to ground the car. I opened and saw one pulley had its grease out and was not running smooth. I will replace this pulley and try again the car. hope it sorts out the problem.

  14. Howdy,

    I own 2 soobs but have a tricky question about my 2006 WRX Sportwagon. I bought this car new, it has no power mods (unless you count a louder muffler) it has SPT pink springs. Been to 2 track events several years ago but, it’s really a daily driver.

    The above just for reference. The real question is this. The manual says to change the belt at 105K miles OR 105 months. I took possession of the car in October of 2005. It is a daily driver, well maintained and run with synthetic oil changed every 6 months. Other fluids/maintenance changed per the time side of the schedule. BUT, the car has just under 50K miles. Yes, fifty thousand. (my job is only 11 miles away and we drive the wife’s 03 H6 after-hours and weekends)

    If this were your car, when would you change the TB and other timing components?

    thanx in advance


    1. Hello

      Yes I would change the belt and components based on age if the mileage is going to take a while to accumulate.

      The Rubber ages and stretches with time.

      The cam shaft timing will be more mechanically accurate and the engine more efficient if the belt is not stretched.


  15. One week ago I had all the belts replaced and the timing chain. Now I hear a squealing noise when I accelerate, could one of the belts be gone already

  16. Hey, I have a 2006 Subaru Outback which I purchased new. I had the timing belt replace on at 110,000 miles. I now have 122,000 mile on it and the pulley has failed, the belt is shot and the plastic housing was sucked down into a valve and bent a valve stem. Do I have any recourse with the original mechanic? What questions should I be asking?

    1. Hello Mary,

      Sorry to hear about the trouble, there are a lot of variables that I don’t have the answers to to be able to answer for your question.

      Were the idlers and tensioner also replaced at the time of the timing belt or was it just the belt? If they were you may have recourse, if they were suggested and you said NO, you have no recourse, if they were never suggested you may have picked the wrong shop and probably don’t have recourse either.

      Hope that helps


  17. Hi Justin,
    I recently had the short block replaced on my 06 Legacy 2.5i along with the tensioner. It was noticed by my Subie tech there was a oil dripping from the old tensioner and there was slivers of meteal in the oil from the block.It’s running great again, but there is now a slight rattle when under load at 25%+ throttle aftere warming up. It sounds internal. Shields are all tight and there is no loss of power.Could this be tensioner related? or something else? Thanks Steve

    1. It might be the piston slap in the replacement shortblock is greater than what came out and it could improve as it breaks in, or there could be something more serious going on, id let the shop who performed the service have a listen to both your concerns and the noise and take things from there.


  18. Hi Justin

    I have a 99 Subaru Legacy, 2.2 engine, auto transmission, 210K miles. Has always run great over the years and maintenance has always been kept up. There was a new timing belt put in at 190k miles, along with a new water pump and accessory belts. I’m not sure if the timing belt idlers have ever been replaced though. A few weeks ago I noticed a slight high pitched whining noise while driving, too intermittent to be able to tell under what driving conditions the noise was made, followed shortly by the engine idling a little louder than I’m used to. When I made the trip to Moab, UT (about 4.5 hours from where I live in Colorado), the car drove just fine, it just idled louder than I’m used to still. After a 45 minute drive to Canyonlands, the engine was idling way louder along with a whistling/whining noise. Checked the oil and belt tensions, both fine. Upon starting the engine back up it ran for about 5 seconds then died, almost like when a manual stalls out. Let it sit for a half hour then ran fine again and made it most of the way back to my house in CO the next day. On the highway driving back the engine started making a loud grinding noise so I pulled off and got towed the rest of the way. Aside from the noise the car still drove fine, no loss in power or anything.

    I recorded this about a week later, and this is the noise its still making. Could this be something related to the timing belt idlers or something else belt related?


    1. Hi Conner,

      Thanks for the Audio file I am having a hard time isolating it from here. Sorry almost sounds like the timing belt slapping the cover, but it could also be valve train related.


  19. SO my 2003 Legacy Manual Transmission wagon has only 35k miles on it. Never driven on hot long trip. Always used synthetic oil after break-in every 3-4k miles (once per year). No noises. No symptoms. Great car. Car is now over 105 months old. Do I REALLY have to replace the timing belt based on time, not miles, of course.

    1. You don’t have to do anything, I can almost promise you that the belt will not make it to 105k based on use, so you can decide when to do it.

      If it was me I would do it because of the stretch factor not fear of breakage.


      1. Justin – thanks. But for clarity – stretching can lead to jumped timing. Please tell me if these 2003 2.5 liter (non turbo) engines have valve interference and hence engine damage under a slipped timing scenario. If not, then I might go for a while. But what is a reasonable “while?” 45k miles and 12 years of age, say? 50k miles and 12 years?

        1. Hi Charles,

          The stretching leading to jumping is just one component, a stretched timing belt makes the engine less mechanically efficient.

          Its merely an opinion about whats reasonable, what would I do do to my car at ten years regardless of mileage it would get a new timing belt, if I let it go that long.


  20. I have a Subaru Outback Diesel. It has currently had 4 drive belt tensioner leak. They last not even 5000 and the engine will start to rattle like crazy. They keep telling me it is safe to drive until I get get back in. I have now probably done 20000km in will it has been loose. Surely there is something causing this and not just the tensioner being faulty every time? do you think there would be any damage to driving it like this?

    Would be interested if you have any thoughts to what it could be. Its going back in middle of next week to get fixed under warranty. Just hope they work out what is happening?

    1. Hi Scott,

      I am sorry but Ive actually never had a diesel Subaru apart as we dont get to enjoy those cars in the US. But whats curious about your post is that he Boxer Diesel is timing chain driven and does not have a timing belt. If by some chance you have a Gas engine Subaru Outback the common thing that affects the tensioner is the bracket.


  21. Hi Justin,
    Over the summer i found a 2000 Subaru Legacy with 150k that was being sold for $500. I had to do lots of work on the car, i work on it whenever i’m home from college and it now runs great! However, it seems that the timing belt tensioner keeps failing, almost immediately. The tensioner i originally bought was not a genuine subaru part, and the belt jumped at least 15 teeth. I got lucky and the engine still ran well after i got a warrenty replacement tensioner. However, about 4 engine hours after installing the 2nd new tensioner, the timing belt jumped 4 teeth and the tensioner no longer put adaquate tension on the belt. So i got a 3rd warrenty replacement on the tensioner at the local auto store, and this time i decided to keep the timing belt cover off of the engine, so i could monitor the belt tension. This 3rd tensioner worked for about 2 engine hours and upon checking the belt tension the next morning, i could slip the safety pin back into the tensioner. What could cause 3 tensioners to fail? Am i really that lucky, or is there something else that could be happening? Thanks!

    1. So I still dont know if you are using a Genuine Tensioner from your post?

      If you are using the OE Tensioner I would install the updated tensioner bracket, look to see if the crank shaft guide is installed correctly (if its a manual) Maybe you are using an aftermarket timing belt thats to long, maybe the heads have been machined to much and there is too much play in the belt above and beyond what the tensioner can do. I could go on for a bit but you have some things to check.


      1. Thanks for the advice, i am using an aftermarket belt and tensioner and it is an automatic transmission car. When i replaced the original badly failed head gaskets which had failed in every way possible, literally, i noticed the timing belt did not have tension, so i will try the updated bracket and belt and go from there assuming the car had not previously had head work.

  22. Thank you, Justin!! I scheduled a third appointment for this Friday and I am going to ask to speak to a manager when I get there, too. I’ve smelled coolant twice now when running the a/c and the noise is getting louder. I’m not settling this time. I will let you know how things go. I sure wish your shop was here in Sacramento! Thank you, again!!

    The guy who helped me last time actually told me that if they replaced the power steering pump and that wasn’t the problem then they would eat the cost of the pump. I’m not leaving this time without them figuring out what it is.

  23. Thank you, Justin!! I scheduled a third appointment for this Friday and I am going to ask to speak to a manager when I get there, too. I’ve smelled coolant twice now when running the a/c and the noise is getting louder. I’m not settling this time. I will let you know how things go. I sure wish your shop was here in Sacramento! Thank you, again!!

  24. I have a 2012 Subaru outback 2.51 premium. I have a ratteling noise when the air conditioner is on. It is most prominate when car is put in reverse and when I stop and then accelerate. The noise is not audible when in park. If I turn off the air conditioning, there is no rattle. I’ve taken it to the dealership twice and they do a multi-point inspection and find no problems. One guy thought it might be the power steering pump, but they don’t know for sure. Because the multi-point inspection didn’t show a problem they won’t do anything else. They told me that since I am just breaking in the car the rattle may go away or it may be a noise it will make. I think that is ridiculous.

    Any ideas on what this could be? The car has about 8600 miles. Thank you!

    1. Hi Muncill,

      You need to take it back and have them take care of it, dont settle for the multi inspection didnt show any thing, as checking boxes on a check list isn’t going to yield nay results, Don’t settle be firm and hold “their feet to the fire”.

      I cant know whats going on with out hearing it but more importantly you have a new car warranty in place unless abuse or neglect was involved.


  25. My 2003 Forester had a SCREAMING tensioner…only took a few minutes to locate the noise and < $100 for my dealership to replace. Man, that was a horrific noise that had me very worried at first.

  26. Justin- My 01 outback h6 (180K)has been making a rattling noise from the drivers side engine for a bit. Yesterday it threw simultaneous 301,303, and 305 codes. Any ideas. It runs pretty smooth other than the noise. Thanks

  27. As I understand it, my H6-3.0 has a timing “chain” rather than belt. Do these fall on the 120,000 mile service or the same as for the belt driven powerplants?

    1. Hi Brian,

      The Timing chain is used on the 3.0 H6, 3.6 H6 and now the newer versions of the H4 starting with the 2012 Forester.

      Chains do not a service interval for replacement like a belt does, however if the wrong type of oil filter is used or the oil not changed and level maintained they can wear out and are very expensive to replace about 4 times what a timing cost to replace.

      Hope that helps


  28. How common is it for the bolt holding on the tensioner to fail?

    I had my timing belt replaced a few months ago and shortly afterwards the bolt failed. Needless to say, that was an exciting stop. It appears I was extremely lucky, as I don’t think the belt jumped, but it did make quite a racket.

    1. Hello Andrew,

      Not very common and the new tensioner would have come with a new bolt making it very unlikely.

      Did the threads pull out of the timing belt tensioner bracket or did the bolt itself break?


      1. The tensioner was not replaced, just inspected. I obviously did not get this done at your shop… Bolt itself broke, flush with the block. Tensioner still seems fine with no loss of fluid. However the whole assembly was replaced after the bolt failed.

        1. Andrew S., what did it sound like when your timing belt/tensioner was making noise? I’m trying to figure out whats wrong with my Subaru Outback XT. No ideas as of yet, hoping to find something with some research.

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