How to install your underdrive crankshaft pulley

[Daox]

This is a step by step process on how to install your underdrive pulley and/or replace your crankshaft pulley. Feel free to ask questions or comment.

If you want to purchase one, see here: http://www.aveoforum.com/forum/f104/...-2008-a-11233/




We start by jacking up the front passenger corner of the car and remove the wheel. Make sure to use a jack stand.





Next, we remove the splash guard around the corner of the engine bay. Remove the two nuts shown here (10mm heads)...




...and the bolt and nut (10mm heads) shown here.





Now, we're looking straight at the crankshaft pulley. This is the one tricky thing to do. Thankfully the torque specs aren't real horrible on the Aveo. You have to remove this bolt. It has a 17mm head. The easiest way to do this is with an impact wrench. If you do not have an impact (they're quite cheap for an electric one at harbor freight and its very useful), you'll have to come up with some way of stopping the pulley from rotating which is quite hard with the one axle up in the air.





After the bolt is off, remove the pulley and accessory belt. It should separate from the timing belt pulley shown above. Take some care not to remove the timing belt pulley as this will cause a lot more work to be done.





Now, put the underdrive pulley on to the timing belt pulley. It should slip on a little snug and stay in place. If it doesn't, you'll have to hold it on while you tighten up the bolt to hold it on. I believe the torque spec is ~76 ft/lbs. There is a small key and keyway that must line up, so make sure that happens.





Next, install the accessory belt. I recommend getting a new belt sized 730k6 vs the stock 740k6 as I had problems with the stock belt squealing. To get the belt on, I used a crowbar to pry the belt tensioner as shown. After the belt is on the tensioner pulley a little bit I removed the crowbar and tapped it on the rest of the way since the idler is smooth.

edit: Or use a wrench on the tensioner bolt to push the pulley inward.




Thats just about it! Your pulley is now installed. You just have to replace the splash guard, put your wheel back on, and drop your car back down. The whole process took me less than 30 minutes. The impact wrench is the key to making this easy.


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[petrified.rabbit]

nice write up, i would only change that you should use a wrench on the center nut of the tensioner to wind it in, since its plastic, and your prying against ribs in another pulley. (i'm sure you were careful but not everyone will be).. also with a wrench nothing will be in the way so you can slip the belt the whole way on. and not need to slip the crowbar underneath it either..

sometimes an impact will turn the engine over too, i've found that out.. so if you go the route be patient. as long as you dont pull the timing gear off accidentally (as mentioned) no harm will come from the engine turning over a few times before breaking the bolt loose.

i know you have had this on, noticeable difference? what about mpg anything there(should there be?)?

[Daox]

Good point with the tensioner. I added it to the instructions.

There is a noticeable difference. It isn't huge, a couple horsepower. I can't say if you'd see anything noticeable in the mpg department.

[AveoJoe]

what do the pulley look side by side. Other then it being made of lighter material what was the diff in size? Sucker looks huge oh and weight what was the diff on the scale? thank you.

[Daox]

The stock pulley is 5.4" in diameter the underdrive pulley is 4.63" in diameter (15% underdrive). Stock weight is 5.5 lbs, underdrive is 1.2 lbs.

I'll have to get a comparison pic of the two.

[one_man_jam]

so just to be sure again...the stock size belt does work?

[Daox]

I would recommend getting a new belt (730k6 is the size). The stock 740k6 belt did work for me, but squealed. When I went to replace it with another stock sized belt, the new belt must have been a little longer and was looser than my old belt. Thus, I recommend getting a 730k6. It may or may not be absolutely required.

[one_man_jam]

oh ok. just wanted to know before i take everything apart =)
thanks though. i'll head out and grab a new belt then.

[dleebold]

thanks daox,i'll try to put the pulley on this weekend.i do have a question though;what's a daox???

[petrified.rabbit]

It's kind of like a Chicago bison?


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