How to install your underdrive crankshaft pulley

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/


http://aveoforum.com/pictures/pulley08.JPG

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



http://aveoforum.com/pictures/pulley09.JPG

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


http://aveoforum.com/pictures/pulley10.JPG

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



http://aveoforum.com/pictures/pulley11.JPG

Now, we're looking straight at the crankshaft pulley. This is the one semi-tricky thing to do. Thankfully the torque specs aren't real horrible on the Aveo. You have to remove the crankshaft 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 get some help. Have someone shift into gear (or leave in park), and push the brake pedal down while you use a breaker bar (and possibly an extension) to get the bolt loose.



http://aveoforum.com/pictures/pulley12.JPG

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. :)



http://aveoforum.com/pictures/pulley13.JPG

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.



http://aveoforum.com/pictures/pulley14.JPG

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, use a wrench on the tensioner to pry the belt tensioner. Do not do as I did with a crow bar. It works, but the wrench is better and easier.


http://aveoforum.com/pictures/pulley15.JPG

Thats just about it! Your pulley is now installed. :D 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.

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?)?

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.

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.

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.

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

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.

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

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

It's kind of like a Chicago bison?

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Originally Posted by dleebold

i do have a question though;what's a daox???

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It's a secret. He won't tell me either.

Anyway, still a good write-up, Mr Doax.

Re: loosening that 17mm bolt holding on the pulley...

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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.

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If you don't have an impact wrench (or even if you do, but it's spinning the engine):

One option is to apply the foot brake to stop the transmission (thus the engine, if it's in gear - manual tranny) from turning. That will give you some resistance to work against. You can still do this as a 1-person job if you wedge something the right length between the brake pedal and the front of the lower seat cushion. You can slide the seat forward to press down & hold the brake.

Works best if the engine has been running recently so there's vacuum assist still in the power brake system.

Not sure if this will work with an automatic. Will work with a manual transmission though. With an automatic, will the parking pin keep the engine from turning with one wheel in the air? Dunno. I've only owned one automatic and that was a long time ago.

How is the butt dyno?

Any difference?

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Originally Posted by XJCasper

How is the butt dyno?

Any difference?

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I did my change over the weekend while doing an oil change. I think it's a little quicker on the start. I did drive 300 miles yesterday back to my new home in SC and had a drop in performance on MPG, 29.80. Usually around 32. Granted I did drive hard on my trip. My average speed was around 80 plus. So over the next week I will be doing more laid back driving between home and Greenville and I will monitor my MPG. I changed my air filter around October. How ofter should I change my air filter?

i can't get that damn crank pulley bolt off!!!! used an air impack gun,but my compressor must not have enough umph!!! called my mechanic down the street and he's going to do it next monday.(decided to do this before i broke something),mechanic i am not.i'll post next week.:dontknow:

My pulley came off easily. I had broken the tightness when I replaced the timing belt. This is what I did to get the damn thing off originally: Since it is heavy steel, I used channel locks directly on the pulley by gripping the inside and outside to hold it still. I then was able to break the nut. I would not do this with the Alloy Underdrive pulley and the channel locks teeth would damage the belt groves.

and old timers trick i learned. Go buy yourself a "rough" leather belt, in like a size 40ish.. On one end, cut a slit, or stamp a hole wrap and sew a ring on the end.. whatever. wrap it wet and tight around the pulley the full length.leaving enough off the end to stick a screwdriver or pry bar through the hole and against the pulley.. hod it tight it will create enough friction (most of the time) to either let the bolt break or slam your knuckles off something really hard.

called another mechanic and he could get it in.the last post were great advice.but to be truthful,before i got really mad and broke something(knuckle,bolt,car slips off of jack stand,strip socket,torn serp-belt,thought i better leave it to someone who knows what they are doing.cost was $30.i have a scan gauge and noticed like everyone else a performance gain.i also noticed a gas mileage improvement.before the gauge would fluctuate between 26mpg and 35mpg.on the way home it was 32mpg and 47mpg.i'll have to run a few tanks of gas to see how much of a mpg gain we can expect.hopefully a bunch.crank pulley is around 5 lbs lighter so should be better on gas and a performance boost. :blob:

I just got done with an other tank of gas with easier driving than my manic 80 MPH+. I measured 32.95 miles per gallon (33 MPG). I am very pleased. Now to see if it is going to be consistent. Interesting enough I noticed a audible change in engine sound. Has anybody else noticed a change? It sounds a little more meaty. Granted I have a SVP with the add on AC. I think the arrangement is slightly different from an Aveo with factory AC.

I used a Dayco Poly Rib Belt 5060740 6PK1880. I am not sure how to read the part numbers and which of those numbers is the length. I had to move my tensioner all the way out to slide the belt on. Will the belt stretch over time? Should I get a slightly bigger belt?

i believe you are running the stock size belt there xintersecty.. 740mm..

I bought the belt over the summer to replace the existing belt (BTW it was a Car Quest OEM belt and still solid at 70K miles). I have the Special Value Purchase model Aveo with a dealer installed AC. When I tried to install the new belt it would not go on. I had two choices, the belt was too small or the parts guy gave me the wrong length. I never took belt back and used it for this setup. The dealer installed AC has the compressor slightly out from the factory installed AC hence the bigger belt.

@Rabbit (thanks for the advice) do you know if tension should be halfway point ideally? I don't have experience in this area. All my experience is setting up belts on VW Beetles using a V-Grove and washers to change the pulley ride height.

Well, if its works and doesn't squeal thats good. In summer mine may not squeal, but as you can see from the pics, mine is in rough shape. The new 740 belt I got was a bit looser than my OEM (which is supposed to be 740 as well) so I decided not to use it.

What is that nice looking pully for? Purpose?

SORRY BUT I THINK ITS A WASTE? The smaller lighter pulley is the same as removing 100lbs from the car where in turn can give more horse power 2-5 more H.P. Anyone feel a difference yet?

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Originally Posted by Binobanana

What is that nice looking pully for? Purpose?

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Check out this link: http://www.aveoforum.com/forum/f104/...-2008-a-11233/

The pulley is lighter than the OEM pulley and also smaller in diameter. This spins the accessories slower and frees up some power.

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SORRY BUT I THINK ITS A WASTE? The smaller lighter pulley is the same as removing 100lbs from the car where in turn can give more horse power 2-5 more H.P. Anyone feel a difference yet?

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You can feel a difference. Its not huge but its definitely there. I'd say its comparable to installing a cold air intake on the car.

It's a little car with a little engine. Remember little things do add up. Personally I think it's going to give me a reliable extra 1 MPG. Given 10 gallon tank that can increases my range from 320 miles to 330 miles.

Quote:

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Originally Posted by AveoJoe

SORRY BUT I THINK ITS A WASTE? The smaller lighter pulley is the same as removing 100lbs from the car where in turn can give more horse power 2-5 more H.P. Anyone feel a difference yet?

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Removing weight from the car does not give you more hp, it give a better hp to weight.

Only thing that add hp are engine mods..

But why not do both? $150 for 3-4(guess) hp from the pulley and 100lbs of weight savings = even faster.

A cai, this pulley, and a non oem muffler will really improve acceleration..

I just put my pulley on and was wondering if anyone else got a little rattling noise when they first put the pulley on? It doesnt make the noise after i start driving because i took the car out to warm it up but it made it when i first turned the car on. It sounds like 2 metals clinging together but it comes and goes. Was just wondering. And i do have the 730k6 belt on.

Quote:

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Originally Posted by AveoJoe

SORRY BUT I THINK ITS A WASTE? The smaller lighter pulley is the same as removing 100lbs from the car where in turn can give more horse power 2-5 more H.P. Anyone feel a difference yet?

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Disclaimer: I don't have one and don't plan on buying on unless the cost comes down.

That being said, if the pulley is like removing 100 lbs, that's removing around 5% of the total curb weight. I don't think that's anything to scoff at.

22lbs per hp stock
21lbs per hp with the pulley

Approximately a 5% improvement again.

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Originally Posted by exodus0784

Disclaimer: I don't have one and don't plan on buying on unless the cost comes down.

That being said, if the pulley is like removing 100 lbs, that's removing around 5% of the total curb weight. I don't think that's anything to scoff at.

22lbs per hp stock
21lbs per hp with the pulley

Approximately a 5% improvement again.

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not bad for $150 :D

you guys have to join in on the fun!

when i put mine on, ill see if their is any differences 1/4 mile wise and other times, 0-60 would be a good measurement as well

this is true I spent more for my header and they did give me about 15+ hp. $150+ 5? for shipping? Ill think about it. I'm redoing my exhaust as we speak new muffler and pipes.

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Originally Posted by AveoJoe

this is true I spent more for my header and they did give me about 15+ hp. $150+ 5? for shipping? Ill think about it. I'm redoing my exhaust as we speak new muffler and pipes.

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But has anyone tested that 15 hp increase?

gary got about 15hp out of his header, i think he dynoed it to show the improvement. BUT he also had already been making close to 140 hp and had an intake pistons, cams and the rest of the exhaust to utilize the extra flow. He also did some dyno tuning i believe to get that number..

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Originally Posted by reddemonx92

I just put my pulley on and was wondering if anyone else got a little rattling noise when they first put the pulley on? It doesnt make the noise after i start driving because i took the car out to warm it up but it made it when i first turned the car on. It sounds like 2 metals clinging together but it comes and goes. Was just wondering. And i do have the 730k6 belt on.

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So still wondering if anyone had this problem or not?

did it only happen one time? might have been the tensioner winding out?

dimensionally there should be no obstruction.. so tensioner pulley is most likely.

i thought he only got about 5-6 on a stock aveo, but 15hp is very possible with other major mods, the stock one is just so bad

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Originally Posted by thehunterooo

i thought he only got about 5-6 on a stock aveo, but 15hp is very possible with other major mods, the stock one is just so bad

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That does sound more reasonable.

Thank you

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Originally Posted by petrified.rabbit

did it only happen one time? might have been the tensioner winding out?

dimensionally there should be no obstruction.. so tensioner pulley is most likely.

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Yea it doesnt do it anymore so i thought it was just since the part is brand new it had to warm up. because it only did it the first night i started running it after i installed the pulley.

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Originally Posted by XJCasper

That does sound more reasonable.

Thank you

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