I mean the pulley rotates, and you need to hold it still with something in order to screw/unscrew bolts. I have found out, it is possible to unscrew bolts by using a second ratchet/breaker bar to hold on to another bolt in clockwise (tightening) direction. Although this tightens the second bolt to some extent at the same time you unscrew first bolt, if you repeatedly loosen all bolts in this way, all bolts will come loose eventually because this method does not tighten bolt more than it loosen bolt, as friction plays a part.

Now my question is, how do you tighten all bolts? You cannot do the reverse as this method loosen more than it tightens.

  • You don't tighten/untighten the 2nd bolt. You just use the 2nd wrench to fixate the pulley by working against the rotation of the whole pulley around the axis. So you are on the right track already.
    – Tonny
    Jul 23 '15 at 12:23
  • Closely related (my answer contains the same trick as Paulster's here): How do I remove a pulley where I have no way of stopping it turning anti clockwi?
    – jscs
    Jul 23 '15 at 18:33
  • Hi Tonny, like I said in the question, your method can loosen bolts, but cannot tighten bolts because the counteracting ratchet would loosen the other bolt while you are tightening one bolt.
    – David Xu
    Jul 24 '15 at 11:03

I usually use a flat blade screwdriver sideways against the face of the pulley. Jam it either between the centre bolt and one of the three or four you are removing or jam it over old bolt and under the other.

Hard to explain but this picture kind of demonstrates what I mean;

Jammed screwdriver against pulley

  • 1
    From experience, it's a good idea to not use a screwdriver you care about with this approach because it can bend.
    – Zaid
    Jul 23 '15 at 15:20
  • I've used this approach before, quite excellent. A variation of it, if there is not a protrusion in the center, use the bolts themselves by placing a wrench over bolt A while holding the grip of it flush with the rotational plane of bolt. This will allow you to use a second wrench, or a ratchet, to tighten bolt C. The thing about this is to be careful, because this method can bend the bolts you are using to brace the pulley if they are not at least hand tightened themselves.
    – Sidney
    Jul 23 '15 at 19:09
  • This method is useful but does not deal with concave pulleys.
    – David Xu
    Jul 24 '15 at 11:06
  • I've found it works even with concave pulleys. Jul 24 '15 at 12:22

Wrap the serpentine belt completely around either ribbed pulley part and hold it on one side to gain purchase (grab both sides of the belt in one place with one hand). Believe me when I say this will give you more than enough purchase to get it done.

If you do not have enough purchase by just using your hand, try wrapping the belt around the pulley and grabbing the belt with a pair of Vise-Grips (or other locking pliers), then grab the Vice-Grips and have at it. This should give you enough purchase.

enter image description here

The arrows denote where the Vice-Grips should be placed. Get the Vice-Grips as close to the pulley as possible. Use enough gripping force to grab the belt so it won't slip, but not enough to damage or destroy the belt itself. You can roll the Vice-Grips back on the pulley for more purchase (will cinch up the belt for more grip on the pulley).

  • 1
    This is a compelling argument for keeping a spare worn out belt on hand so you can safely "clamp" with the belt without fear of damaging it in the process.
    – Saiboogu
    Jul 23 '15 at 16:20

You need to find another way of stopping the pulley from turning. Are there any holes in it you could use to wedge it with?

One technique I have used is to wedge a bit of bar diagonally between two of the bolts, then (un)tighten the others, rotate and repeat...

  • What about concave pulleys?
    – David Xu
    Jul 23 '15 at 11:54
  • Or use a 2nd wrench on another bolt to fixate the pulley. You're not actually trying to tighten/untighten that 2nd bolt. Just counteracting unwanted movement of the entire pulley around the axis. Will work on any shape of pulley, because you must have access to all the bolts.
    – Tonny
    Jul 23 '15 at 12:20
  • @DavidXu I've done it on slightly concave pulleys. Very concave ones would need a non-straight bar, or suitably shaped bit of metal...
    – Nick C
    Jul 24 '15 at 8:57

A technique I use is to tighten the bolts while holding the pulley by hand. Then install the belt. The tension of the belt will hold the pulley so you can finish tightening the bolt to the required spec.

  • What do you do in cases where belt cannot hold pulley?
    – David Xu
    Jul 23 '15 at 11:55

If space permits, use an impact wrench to loosen them. If the impact wrench has some kind of torque-limiting capability then you can use then to tighten the bolts as well.

  • Can you confirm at the shops they use impact wrench to do this kind of jobs without worrying about holding the pulley?
    – David Xu
    Jul 23 '15 at 11:58
  • @DavidXu, are you going to be doing this at a shop? If not the method by which they perform the work in a professional shop is irrelevant to a DIY question. You just need to know the correct way. Shops have been known to use impact wrenches even for jobs where using them is a bad idea. I have not seen the use of an impact wrench for pulleys (there is generally not enough room) but I have seen the use of a pneumatic or electric ratchet. Jul 23 '15 at 12:48
  • @DavidXu : Regardless of whether or not shops use it the technique does not require you to hold the pulley in place because the sufficient impulse is enough to crack the nut/bolt open. Again, this is if space permits.
    – Zaid
    Jul 23 '15 at 13:02
  • @Mr. Mascaro, The pulley question is an important question and it pays to know how the professionals handle this problem. Many jobs cannot be done properly by DIYers because without proper tools, you cannot do a proper job. The pulley issue can leave you stranded on motorway which is dangerous. Also it is not expensive to buy air tools. They normally turn out cheaper if you need to have a range of auto tools as well as home renovation tools. For example, a framing nail gun powered by air is cheaper than a fuel cell one. So you can buy one air compressor and use on many tools to spread the cost
    – David Xu
    Jul 24 '15 at 11:13
  • @DavidXu, actually you are 100% wrong. Knowing how the professionals do it can cause you a lot of problems because many of their techniques not only require special equipment but special technique and practice. If you read my comment, the reason for that will be clear. Using an impact wrench on a stuck bolt can snap the bolt. Wanna talk about being stranded on the highway? In a shop it's easy to fix. On the side of the road you'd be calling a tow truck for sure. That's why it's irrelevant for a DIY person to know. You don't know how and why to use the tools. Jul 24 '15 at 12:43

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.