Tips for tightening Alternator belt?

[JayEstes 172]

Guys,

I had an alternator belt go wimpy on me recently, I went to tighten it up, and it was a reminder that I don't really have a great method for getting some good tension in the belt.  I have a 302, Alternator on the passenger side, and it seems like there is just not a good way to really pry & hold  the alternator in position to get the belt nice and snug.  I tried a large prybar against the engine, but this time I would up cutting a small hole in the heater hose (pinched against structure) which was a pain to have to fix.

The power steering unit has a nice lip on the housing that allows you to use a regular screw driver to pull up on the housing and get plenty of leverage to tighten that belt. 

Anybody got a cool tool for this, or a tip for how to get good leverage on the alternator housing while still having a free hand to tighten the bolts to hold it in place?  Seems like such a basic thing, but I couldn't find any tips using a search of this forum.

Let me know of your best advice on this.  Pictures encouraged as always.

Jay

[MN69Grande 203]

Well.  I'm sure there are other ways.  But I got so sick of belt squeak for both the Alternator and PS that I bought this tool.

https://www.mscdirect.com/product/details/35438209

You put it on the inside of the pulleys and use a wrench to have it push out until there is enough tension on the belt.  Tighten your bolts, un-tighten and remove the tool.   Makes it SO easy and nice to do by yourself. 

[Mike65 475]

When I had my 68 GT w/302 the pivot for the alt was on the bottom of the alt, & the bolt to tighten it was on the top. To tighten the alt belt I would find a open end wrench that would fit the square piece where the bolt threaded into & use that to pull the alt tight. See attached link; https://www.cjponyparts.com/alternator-standard-single-pulley-65-amp-1965-1973/p/ALT1/

[Brian Conway 264]

Not the professional look but works for me.  Find a spot where a wood wedge will fit and drive it in.  I find uses for these wedge's in many situations.  They won't break anything and usually don't leave any marks behind.  Brian

[Bob & Sue 110]

4 hours ago, MN69Grande said:

Well.  I'm sure there are other ways.  But I got so sick of belt squeak for both the Alternator and PS that I bought this tool.

https://www.mscdirect.com/product/details/35438209

You put it on the inside of the pulleys and use a wrench to have it push out until there is enough tension on the belt.  Tighten your bolts, un-tighten and remove the tool.   Makes it SO easy and nice to do by yourself. 

I have the same tool it works great probably had it for 30 plus years.

[aslanefe 333]

2 hours ago, Mike65 said:

When I had my 68 GT w/302 the pivot for the alt was on the bottom of the alt, & the bolt to tighten it was on the top. To tighten the alt belt I would find a open end wrench that would fit the square piece where the bolt threaded into & use that to pull the alt tight. See attached link; https://www.cjponyparts.com/alternator-standard-single-pulley-65-amp-1965-1973/p/ALT1/

+1 on using an open end or adjustable wrench on the square ear where the bolt threads on to.

[Bob & Sue 110]

Here's a pic of the one I have. I've used the wrench method too this tool makes it simple.

 

 

[JayEstes 172]

8 hours ago, Brian Conway said:

Not the professional look but works for me.  Find a spot where a wood wedge will fit and drive it in.  I find uses for these wedge's in many situations.  They won't break anything and usually don't leave any marks behind.  Brian

That's actually what I wound up doing after pinching the heater hose.  Worked pretty well, took me 3 or 4 tries to get the right sized block, but that made a nice leverage point when I did.  Overall, functional, but felt ghetto.  A good free solution for sure - dissatisfies the mechanic in me tho..

[Brian Conway 264]

Yes I have a selection that I keep in the specialty tool section of the workshop.  Brian

[JayEstes 172]

6 hours ago, Bob & Sue said:

Here's a pic of the one I have. I've used the wrench method too this tool makes it simple.

 

 

I just bought one of these on Amazon.  Looking forward to this, should make things alot easier.  Am I right in assuming the fatter end of that tensioner is threaded, and you just twist it to drive the jack out (hence, push both pulleys into the belt) to tighten?  That looks like it might be hexagonal, the one I bought looked round though.

[Bob & Sue 110]

37 minutes ago, JayEstes said:

I just bought one of these on Amazon.  Looking forward to this, should make things alot easier.  Am I right in assuming the fatter end of that tensioner is threaded, and you just twist it to drive the jack out (hence, push both pulleys into the belt) to tighten?  That looks like it might be hexagonal, the one I bought looked round though.

Yep it's a 3/4" hex made by Garage Pro.

They make it easy by freeing up your hands to get the correct tension on the belt & scraped knuckles.

I have one for serpentine belts somewhere that I used on Mercruiser engines the belt length was 106" on 6 or 7 pulleys it also had a dial to set how many lbs of tension was on the belt with a laser to align the pulleys to the crank pulley. Mercruiser doesn't have a self tightening tensioner like a car.