All Wheel Drive Auto: Independent Seattle Subaru Service


Subaru Repair Seattle: Timing Belt Idlers Explained

This comes up a lot both for our Local customers, and we get a lot of questions about this from afar.

The old saying a picture is worth a thousand words, I think a video with a little sound is worth many more.  I did make a mistake about the green aftermarket idlers we see in many of the online kits having double bearings, that is actually not correct, they are just a single bearing idler, which is really not the best choice you can make .  It only costs a few dollars additional to get the updated component.

Thanks for reading and watching



28 Responses

  1. Howdy, thanks for posting such helpful info! I have hopefully a simple question for you:

    Which pulley/belt/tensioner is not engaged when the car is in neutral?

    I don’t get at unusual noise (such as the common timing belt tensioner noise) when I rev the engine to 2000 rpm, BUT DO get the noise when the car is in drive (for example when driving, or pushing on the brake but having the car in drive and pushing on the gas pedal will both replicate the same clanging/knocking/metallic noise, but only around 2000 rpm (give or take a few hundred rpms).

    Thanks for your time!

    1. Hello Joshua,

      I don’t completely understand what you are asking?

      “Which pulley/belt/tensioner is not engaged when the car is in neutral?”

      All engine pulleys are “engaged” regardless of transmission gear.

      There is however increased load on all sorts of components when the car is in drive VS neutral or park or when the AC compressor cycles or when you turn the steering wheel or even just when you turn on the head lights, its better to just isolate where the noise is coming from if you can rather than try and figure out which one might be under more load at a given time.


  2. I have a 1993 Impreza Wagon (1.8L). I’m overdue for my second timing belt replacement. It’s recommended at 60,000 miles or 60 months. Only the belt was replaced the first time around and the water pump went about 3 months later. I was planning to have the water pump replaced too this time. Have I been lucky to get this far without replacing the tensioner and idlers or were the parts made better then?

    1. 1993 Impeza is a non interference engine, if one of the idlers failed it would not destroy the valves, but yes its still a gamble to ignore them as being stranded and damaging the belt wouldn’t be any fun either


  3. I am looking at buying a 2001 OutBack for my daughter to drive across the country to college. It has only 47K miles. I understand that you would normally replace the timing belt at around 100K miles, but I wonder if you would recommend replacing now since it is ten years old.

    Thanks for all the great information on your site. It has helped me immensely.

  4. I bought a 2002 sub 2.5 for my daughter 4 years back. I have a 2002 wrx wagon..Now her sub has 107000 K on it and when it is cold, (we are in Canada) it has a definate tic going on. sub experts here tell us that it’s piston slap…OK? it goes away after it warms up. Now reading this , I think it might be the timing belt idler, going wacky until engine temp goes up. what say you, oh sage…

  5. Justin, Thanks for the tip. Automatic on this one though. I spun everyone and no obnoxiously loud suspects though all but the tensioner bearing do appear somewhat worn. Can these idler pulleys squeel at high rpm?. Can the belt itself squeel if the tensioner isn’t quite doing it’s job anymore? Can waterpumps squeal even if the pulley feels nice and tight and they are not leaking at weep hole? Found the correct kit if you are interested, though you likely are getting better parts elsewhere price was right at $292 w hydraulic tensioner and the one idler pulley even has the double bearing (nice refernce by the way on that a most kits do not have that). Said the H with it and got it all including water pump so at a minimum all will be done and hopefully (double crossed fingers) no squeal. I must say excellent site you have and used your tip previuously about the foaming power steering fluid after belt change….that was an odd one that would have taken a month to figure out on my own.

  6. Hi Andy,

    It would be wise to remove the timing belt and spin each idler and the tensioner pulley as well.

    Also if it is a 5 speed, there are 2 other things to consider, one is the timing belt guide not gapped correctly over the crank shaft sprocket and the other is a throw out bearing or clutch fork/pivot point issue.

    Hope that helps


  7. Can potentially worn timeing belt idler pulleys squeal or sing at about 3500 rpm and up? Sound is not as obnoxious as say a water pump, sounds more like an hones belt squeel. I sware it is a two pitched squeel with one kicking in about 3500 and the other kicking in about 4500rpm. Won’t do it in the driveway, engine must be under load. Not the accessory drivebelts or pulleys as I took them off. Whole timing cover now apart. Belt looks great (replaced prev. at 49K mi by dealer) but wondering about these idlers and how to test tensioner. When I rotated crank with socket it sure looked as if timing belt was shifting forward just slightly on the left cam pulley before everything began to turn together. To me T-Belt seemed just a little bit looser than I would have expected based on previous experience w VW and Honda 4 cyls. Idlers do not seem bad (maybe give the worst one a 1/2 skateboard bearing rating) but certainly are not “new” either. Subaru (2001 Outback 2.5 w 97K miles)

  8. Change the headgasket on the new engine… It’s easy as pie to do while the engine is out as long as you follow the right procedures… Be aware though, to really do it right you should have heads inspected and possibly decked for flatness otherwise you may run in to problems. With that added expense you can just as well fix the old engine if everything else seems good on it. 🙂

  9. Hello Justin,

    Great website!! I just purchased a 2002 Legacy GT Wagon here in Duluth, MN. 156k on it and the day after the purchase it overheated and I’m told it’s due to a defective head gasket (which according to records were replaced at 92k as well). I have decided to buy an engine (another 2002 2.5l SOHC) with 68k and a 12 month parts warranty on it. The decision I need to make is whether I take my chances and just have the swap done without doing anything to the replacement engine, or take the time (and cash) now to change headgaskets and timing belt parts. I just ordered your head gasket set (in case) but can you quote me a price for a complete timing belt kit (belt, tensioner and idlers)?


  10. Jimmy,

    Its always a good idea to inspect all of the seals, while behind the timing covers.

    I will tell you though that the cam and crank seals used by Subaru right now are some of the best longest lasting seals I have seen.


  11. Hi Justin,
    I might be interested in purchasing a “timing belt kit” from you. Could you specify exactly what it would include and the price. Thanks, Jay.

  12. Another shop mentioned changing the crank seal, oil pump seal, and cam seal as part of the timing belt repair. Is that a typical set of things to replace/inspect at the same time?

  13. Matt,

    I have never seen a kit online that has all of the right parts in it, we do sell a timing belt kit with what we feel are the best possible parts to use.


  14. Kevin, the motor is somewhere around 200 lbs. Maybe slightly more but it’s easily picked up by two guys.

    Justin, I’m also curious of what you would recommend for a “timing belt kit” to compliment the head gasket kit.

  15. Hello Justin

    Thanks for taking the time to add another excellent and informative video to your collection. I’m planning on pulling the engine on our 2001 Legacy wagon this spring (please open a second shop up here in Juneau). 90,000 mile and an oil leak on the lower left rear side head gasket. What are the odds? Along with your head gasket kit I plan on having you include the timing belt, all idler pulleys, tensioner and bracket as well as the water pump, hoses and accessory belts. Are there any additional parts that you would replace in order to help reduce the chances of my having to break into the the engine over the next 105,000 miles. Also, could you tell me roughly what the weight of the engine is when pulling it out of the engine compartment. Thanks again for all your hard work.

      1. Hi Rick,

        Most likley you have suffered valve train damage.

        Would take testing to know for sure however.



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