Replacing my serpentine belt- advice?

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by coppercumin20, Sep 11, 2021.

  1. coppercumin20

    coppercumin20 New Member

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    Hey all,

    Just got state inspection done on my new 2006 prius. Mechanic said I need to replace the serpentine belt, sooner the better. Since I have a long interstate commute, I'm gonna try to knock it out this afternoon or tomorrow. replacing the belt would be my first time doing anything DIY on a car beyond replacing a flat or jumping a battery, but I do have general mechanical experience from working in the ag department machine shop as an undergrad, and I can probably still drop in there to borrow tools. I'm feeling good about the repair. My main areas of concern are buying a good belt and getting the tension right.
    1. What's a good brand to get from auto zone/ advanced auto, if I can't get OEM from toyota (or they want like 50$).
    2. how should the tension feel when I'm done? My plan is to count the turns I used to loosen it and just match in reverse (maybe mark with a crayon for overkill), but I'd like a way to check my work. I found someone say I should be able to twist it about 90 degrees at the longest run, but that's at the bottom and I don't think I can reach that from above
    3. what signs of a mistake should I look for afterwards? What will I hear if it's too loose/ too tight? I'm pretty confident I won't mess up the ribbing, but if i DID, would I be able to hear it? I'm gonna keep the ratchet and sockets in my glove compartment for a while just in case.

    There's some other work it needs that I'll post about later, but right now I just care about the belt.
     
    #1 coppercumin20, Sep 11, 2021
    Last edited: Sep 11, 2021
  2. ChapmanF

    ChapmanF Senior Member

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    For best results, don't use that plan. The correct tension is different for installing a new belt (99 to 121 lbf on a tension gauge) than for reinstalling a used belt (55 to 77), and chances are the current tension on the old belt (which you'd be "counting the turns" down from) is neither, so it's not worth much as a guide.

    You can check without a tension gauge using the procedure in the repair manual (more info) if you have a way of pushing straight inward on the longest free span of the belt with an accurate 22 pounds of force. A new belt should deflect 9 to 12 mm under that amount of force; a reinstalled old one should deflect 11 to 15 mm under the same amount of force.

    But that can be trickier than just using a tension gauge. You should be able to find one at the local auto parts shoppe and it shouldn't break the bank.
     
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  3. Mendel Leisk

    Mendel Leisk Cloud Watcher

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    Repair Manual info:
     

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  4. mr_guy_mann

    mr_guy_mann Senior Member

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    Any major brand of belt should be adequate- I use Gates or Dayco.
    Use a belt tension gauge. Many companies sell the Krikit gauge - you want the one for "V belts" that has a range of 50-150 lbs. (Gates #91107 or Dayco #93865). Read the instructions carefully as these can be tricky to use correctly.

    When you have the old belt off, spin the water pump and the tensioner pulleys- both should fairly smooth and quiet. You shouldn't be able to rock the pulley sideways

    Adjust the new belt to 60-80 lbs, you don't need much because you're only spinning the water pump. Recheck after tightening the adjuster locknut. If everything looks and runs ok, then recheck tension after a week of operation.

    Posted via the PriusChat mobile app.
     
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  5. ChapmanF

    ChapmanF Senior Member

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    That tension's a little lower than what Toyota specs for a new belt, though it's right in the range for a 'used' one.

    Maybe the key is that what they call a 'used' one is any belt that has run for five minutes. So as long as it ends up in the 55 to 77 range after initial tensioning and running the engine for five minutes, I guess they'd call it good.
     
  6. coppercumin20

    coppercumin20 New Member

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    alright so I called about 4 autozones in my area, none of them have any kind of belt tension gauge for purchase, let alone loan-a-tool. One of my neighbors builds corvettes as a hobby, so he *definitely* has some kind of belt tension gauge, but he's not home today.

    I can definitely borrow a torque wrench or breaker bar from like 4 different places. I can still get the swap today, but I can't see how I'm going to get the tension checked before Monday. Trying to decide whether it's better to drive on the interstate with a bad belt, or drive on the interstate with a belt I guessed the tension on.
     
  7. edthefox5

    edthefox5 Senior Member

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    Do not use a parts store belt.

    This is a super important belt if it failed you will never know till the engine over heats. There not expensive at the dealer.

    In fact don’t use any parts store crap on this car.

    spray some lube on the adj bolt. Untension it and take belt off.

    Here’s where you get to check the pump and idler bearing. Spin the pump and listen for any bad sounds, should not hear any should spin nice and smooth no metal on metal sounds. If you have not kept after coolant maintenance don’t be surprised if it does not sound good and pump needing replacement.
    Remove the idler bearing and do the same. I was able to remove that bearing and grease it up. That may sound bad too.

    You will be shocked when you see how bad your belt is.

    put the belt on with moderate tension should be able to deflect it about a 1/4 of an inch. Do not over tighten it. It will stress the water pump.

    Run the car for a few days then check the tension again. New belt very stiff and will break in and get a little looser even more so with after market belt.

    Then since your in there check the coolant level. Never check it by the over flow reservoir take the rad cap off and look in the rad.
    It’s under the black plastic rad cover.

    Next time you post please post the mileage on your car.
     
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  8. Mendel Leisk

    Mendel Leisk Cloud Watcher

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    The repair manual excerpt I posted has an instruction for checking tension without special tools. You push on the belt at a certain mid-point, with a “specific force”, and see how much it deflects.

    Now how to apply that specific force might be tricky. My thought would be to push down on a kitchen scale till you achieve that force, then try to replicate that amount of force pushing on the belt, with a ruler propped beside it.

    BD4873B4-1B48-40E5-AC1B-43A93900814B.jpeg
     
  9. ChapmanF

    ChapmanF Senior Member

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    You can also use something like Ed's method, where you stick your thumb on the belt and say "that feels like about 20 pounds and a shade under half an inch", and make the trips you need to make, and check it with your 'vette buddy's belt tension gauge later in the week when he's home (using the "used belt" specs, as it will have more than five minutes run time by then).
     
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  10. coppercumin20

    coppercumin20 New Member

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    Forgot the mention I'd already bought OEM from a dealership for 20$.

    Okay, I definitely have access to a breaker bar, lube, and a ruler, so I can definitely check the deflection that way.

    Not 100% sure how the maintenance was, I bought this car 2 weeks ago. Test drove it twice AND had a local shop look at it. They flagged it for the rear drum pads being 3/32" (from this forum, not actually a problem on the prius), and suggested I'd have to do the front brakes eventually, but otherwise said it was a good car- belt fine, no leaks, engine good, etc. Between them missing the belt, not noticing the oil was overfilled (noticed it myself yesterday), and not mentioning the coolant was a bit low, I'm thinking there's a reason they were the only ones around available on short notice and that was 120$ very poorly spent.

    Is the overflow reservoir the one that's between the air cabin filter box and the silver box (which i'm pretty sure is the engine)? Where is the radiator? Actually, on that note, is there a thread around here with a diagram of what's under the hood or something? I would really like to know what names things have instead of just describing them all the time.
     
  11. ChapmanF

    ChapmanF Senior Member

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    There are two separate cooling systems under the hood, one for the engine, one for the electronics and motors. They both use the same pink coolant, and there is a translucent whitish plastic bottle for each one.

    The bottle that is closest to the middle of the underhood area, between the engine and the inverter, is the one for the electronics and motors.

    The bottle that is over by the right fender is the one for the engine. You should see pink coolant in both bottles, about up to where the molded lines are.

    The bottle for the inverter is a degas bottle: it's always on the path of the circulating coolant, coolant flows right through it when the car is operating, and air bubbles in the coolant eventually end up, with luck, in the bottle. There is no separate place to fill that system, you just pour coolant in the bottle.

    Starting in Gen 3, the bottle for the engine is also a degas bottle, but in your Gen 2 (and in Gen 1) it isn't. It is an older style called an overflow or recovery bottle. There is a separate radiator cap right on top of the radiator, and you have to fill the cooling system there—right up to the cap (no room there for an air space). Then you also fill the recovery bottle up to the indicated level.

    A recovery bottle is kind of a stagnant backwater in the system. Because there's no air space in the cooling system and radiator, every time the engine warms up, the exapansion of the coolant forces some of it past the radiator cap and into the recovery bottle. But there is never coolant circulating through it. When the car cools down and the liquid in the cooling system contracts, some of the coolant in the recovery bottle (usually) gets sucked back in past the radiator cap to keep the system full of liquid.

    Ed's point was you can't just look at the level on a recovery bottle and be sure the cooling system is full. It's supposed to normally work that way, but if the cooling system ever becomes leaky in a way that allows some liquid out and some air or gases in, then the reserve coolant in the bottle might never get sucked in. You could look at the bottle and think "great, level looks fine there", but still take off the radiator cap and find the actual level in the cooling system to be way low.
     
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  12. mr_guy_mann

    mr_guy_mann Senior Member

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    Napa sells the Krikit gauge (# NBH-KR1) for under $20. Or you can get the previous gates or dayco ones from amazon.

    Posted via the PriusChat mobile app.
     
    #12 mr_guy_mann, Sep 12, 2021
    Last edited: Sep 13, 2021
  13. Fred_H

    Fred_H Misoversimplifier

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    That description sounds more like the location of the windshield washer fluid bottle. The location of the engine coolant bottle is at the very front of the engine compartment, on the right hand side of the car, but near the centerline.
     
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  14. ChapmanF

    ChapmanF Senior Member

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    Thanks for catching that for Gen 2; I could have been remembering something more like the Gen 3 location.

    The Gen 2 radiator cap is certainly at the very front, right hand side but near the centerline, and there should be a small hose from the radiator neck below the cap to the recovery bottle, right near that location.
     
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  15. edthefox5

    edthefox5 Senior Member

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    Rad cap is the passenger side of the rad under the black plastic cover. Make sure car is cool if you open the cap.

    Ice coolant maintenance is easy just dump the rad a few times over a few months. There’s a white drain plug on the rad backside bottom drivers side. You can turn it by hand but be easy on it very easy to break it.
    Get a container under the car take cap off open that white plug drain the rad then close plug and then fill it up to the top with new Toyota LLC.

    Not necessary to screw that black plastic cover back on just put it in place the hood keeps it on. With it easy to take off very fast to check coolant.

    new car to you check everything often till you figure out what’s leaking.
    Don’t be surprised if engine eats oil. Find out how much you run this engine dry of oil it’s new engine time.
     
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  16. coppercumin20

    coppercumin20 New Member

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    Alright, so I got the serpentine belt done! Took me something like 4 hours, but most of that was looking for tools (I kid you not, I went 3 different places just to find the breaker bar). Haven't gotten a hold of a tension gauge yet, but I need to get the car re-inspected anyway so I think I'll just ask the mechanic to check it for me while he's at it.

    Tensioner pulley and water pump belt both made no sounds when I spun them. Tensioner spun freely with just a flick of the wrist, water pump needed to keep being turned (which I'm guessing is how it should be, considering that's what the belt is for).

    The actual inverter is full to the cap with coolant, so it's just the reservoir that needs a bit of topping off. It did have a single bubble, and looking back over the carfax I can see that the coolant was flushed 5 months ago, so I'm wondering if maybe it wasn't bled correctly. Or... so after taking the plastic cover off, I noticed there's pink marks on the drivers side, sort of behind and toward the center from the driver side headlight, below an orange hose. My first thought is that it was the OTHER water pump (there's 2, right?) but looking at some youtube videos it doesn't look like the same shape as what they pull out. The marks are very bright, very distinct. at first i thought someone had just marked the nuts with chalk or something, or done some kind of pressure test. I'll put up photos later and make a new post.
     
  17. Fred_H

    Fred_H Misoversimplifier

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    Be careful saying driver or passenger side. Some people sit on the wrong side. ;-)
     
  18. Another

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    Port and Starboard may be better LOL
     
  19. ChapmanF

    ChapmanF Senior Member

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    o_O did you type 'inverter' meaning 'radiator' ?

    The inverter cooling system is separate, and its reservoir cap is the only cap there is.
     
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  20. coppercumin20

    coppercumin20 New Member

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    Yep. Rad cap. Look, it was 6:00 am and i hadn't had coffee yet.

    Anyway, here's a photo of the belt I took off. Some of those cracks went deep, would have been visible from the smooth side pretty soon.


    I also added photos of the pink marks and the coolant in the radiator. Forgot to take one of the overflow reservoir, but the coolant goes right to the bottom of the word "low". I think my original guess was right - these look like marks to me, although I AM still unsure what this part is. The transmission place that did the coolant isn't Prius specific, so I'm wondering if they just bled the air out wrong. I'll top it off and see what happens.
     

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    #20 coppercumin20, Sep 17, 2021
    Last edited: Sep 17, 2021
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