Correct Serpentine and V-Belt Tensioning?

[The Critic]

How do you correctly tension Serpentine or V-Belts?

The few serpentine belt tensioners that I have worked with appeared to be automatic tensioners.

Are V-Belts tensioned in the same way, using an automatic tensioner?

Thanks.

 

[Merkava_4]

Serpentine belts are automatically tensioned by the belt tensioner.

V-belts are tensioned from human strength by prying against the engine block onto the selected accessory (where the belt loops onto) with a pry bar while simultaneously tightening the bolt on the slide bracket. The correct tension would be a 1.0 inch deflection in either direction.

In the old days, it was common to over tension a V-belt and subsequently wear the alternator bearing out.

 

[The_Jeff]

There are some manually adjusted serpentine belts. Jeep 4.0s come to mind.

Sometimes with manually adjusted belts, like hyundai alternators, there's a jack screw bracket where one tightens a bolt that slowly repositions an accessory or idler pulley to create tension. Then all the other bolts are finally torqued down.

 

[Merkava_4]

Quote:

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There are some manually adjusted serpentine belts. Jeep 4.0s come to mind.

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That's news to me; thank you sir.

 

[chrome]

Many older Japanese models have manual serpentine belt adjustment. Mitsubishi, Mazda and Toyota come to mind.

 

[Master ACiD]

my dodge which is a re badged mitsubishi has manual adjusted seprpentine belts.

the best way to tighten a serpentine belt is to tighten it until the belt stops squealing, and then go a bit farther from there. you don't need them overly tight. as long as it isnt squealing, its not too lose.

 

[74DartSport]

Quote:

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How do you correctly tension Serpentine or V-Belts?

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Get a Gates Krikit (for v-belts) or a Krikit II (for serpentine belts).

Krikit.

 

[Drew99GT]

Tighten until snug but not sloppy; don't CRANK it on till there's hardly any deflection. The rule of thumb is 1/4 inch deflection for the most part but it's better to go by feel IMO; the longer the distance between pullies, the more deflection you'll have, so using an arbitrary number may lead to over tightening.. It takes time to get that feel.

I've been looking for the past 5 years for a tension gauge; still haven't found one yet!

 

[mechtech2]

If you have automatic tensioners, make sure they are free and operating correctly. Most serpentine belts have auto tensioners, but some are manual. I've never seen a V belt with an auto tensioner.
If you have a manual tensioner, run a new belt at medium tightness, and then recheck it after it seats in. It will change and get looser. Mechanics have to set the tension a bit high, because of the expected loosening after it leaves the shop. What else are you going to do?
You don't want your belts as tight as banjo strings. They should have a bit of give to them. Some driven components require more than others - use as little as necessary, not as much as you can.

 

[alanu]

I find that dayco will stretch more than other belts.

Recheck the newly installed virgin belt. Regardless of what brand they will seat into the pulley.

 

[Lonnie]

I like the serpentine belts but the one on my V8 4Runner took some doing go get it back on. I did discover the trick and next time around it will be easy. I keep the 14mm wrench and the old belt back with the jack just in case I ever need it. It came off at 35k miles looking like new, but I changed it anyhow. I got lucky with this model. The belt fits a lot of other vehicles and will be easy to find in the future.

 

[Donald]

What I have done is 1/2" of deflection over the longest run pushing it with your thumb. Measure again a few hours of use into a new belt. Too much and you wear out bearings and too little and you have belt slip. (Forget about belt grip spray).

Check pulleys for rusting or pitting. If you have either (common on boats) you need to either have it sandblasted or replaced, you will never sand it smooth or wire brush it. If the pitted pulley "sands" down the belt it will become smaller and fit farther into the V and also looser. Not a good thing.

 

[MNgopher]

Find your favorite old school parts house and ask for a Krikit. No more guessing if the tension is right (I own a Jeep with the 4.0 and manual adjustments).

In my case, at the NAPA I prefer, it was the "grey haired guy" that new exactly what I wanted, and which book to find the part number in.

 

[The Critic]

Thanks everyone for your responses.