V Belts - How tight is right?

A quick video on how I go about tightening V-belts for any of you who find yourself working on an older car or equipment.

[@Barsomn]

Thank you. My dad is no longer around to teach me this now that I’m working on an older car. Simply and well put!

[@erikstrawn3885]

Thank you for the affirmation. I'm sorry your dad isn't around, but I'm glad that I'm able to share all these tips I've learned over the years. Thanks for watching!

[@ASimpleHeroinUser]

Damn I feel u bro. I lost my pops in November. I still remember a lot of stuff but he's not here for me to double check or lemme know the small details I forget some times

[@ASimpleHeroinUser]

I kept his old truck and been lots of shit to fix lately

[@Snipah7Gaming]

Thank you for this. My belt snapped on my 94 audi and I had no clue how to get the new one on properly. This video was all i needed. Quick, easy to understand and straight to the point.

[@erikstrawn3885]

Thanks for watching!

[@Milner62]

Good video, im going to have to run my belt a bit tighter, 140A 3G alternator on a single V belt. I do have a 6.5s LCR regulator to help stop slip but id still plan on putting a biy more tension on it than that. 1/2" deflection is the rule of thumb. Steaight edge along the belt routing between pullies you should be able to delress the belt down away from the straight edge 1/2". I tend to go more for 1/4" deflection.

[@erikstrawn3885]

Thanks for watching!

[@thisisyourcaptainspeaking2259]

Absolutely, overtightening is a recipe for damaging the driven assemblies such as water pump. Another way of knowing is if you can turn the accessory by hand or slide the belt in the v-groove by hand (causing it to slip), likely it's a little too loose.

[@erikstrawn3885]

Sorry that I didn't see your comment until now. Thanks for the comment and thanks for watching!

[@waynemwangi9444]

I've changed my water pump because it was making noise when setting off or when the AC is on and quiet when we get going, I'm thinking the belt is too tight, will it be too loose if I add 15mm, currently at 1865mm

[@thisisyourcaptainspeaking2259]

@@waynemwangi9444 Adjusting the belt too tight will damage the pump shaft bearings. If this is a v-belt setup, I'd adjust the belt tension just tight enough it's very difficult or cannot turn the pully by hand. The wild card here is a worn v-belt that's become too narrow to properly fit the v-groove, in which case overtightening the belt can overcome the poor fit but in this case overtensioning damages the shaft bearing. A new belt is needed in this case, as opposed to overtensioning the worn belt. Pullys wear too, where a marginal belt must be overtightened to avoid slipping. I've never experienced a totally worn out steel pulley but I have experienced worn-out aluminum pulleys. Replacing the belt is a much better option than overtensioning a worn belt because a worn belt will slip too much even when overtensioned. It doesn't require a ton of tension if both the belt and pully are in good condition.

[@waynemwangi9444]

@@thisisyourcaptainspeaking2259 thank you for your reply. When I changed the water pump I replaced the belt as well. The two are only 500km in. I replaced the belt with the same that was in the car before, where the pump I removed was making a similar noise like the one the new one is making. Belt size is currently 1865mm I want to try 1880mm. I can't adjust tension because the tensioner is automatic.

[@thisisyourcaptainspeaking2259]

@@waynemwangi9444 Sounds like your vehicle has an automatic spring-loaded tensioner and in that case, probably a flat-ribbed belt. You should be using the belt length called for by the vehicle manufacturer, don't attempt redesigning the belt system unless you've modified something. Additionally, be aware the spring-loaded belt tensioners do wear out, so consider replacing it if problems persist or there's any question about it's condition.

[@NapoleonBorn2Party]

Thabk you so much! I neede to replace my belt cos there was squeaking, thankfully no damage to the bearings.

[@erikstrawn3885]

Excellent, thanks for watching!

[@dolittle6781]

Anyone know how to remove a smog pump on a 1977 Buick Regal 350 V8? Would be great to see how to remove the belts or at least loosen them enough to take the pump off…

[@erikstrawn3885]

I don't believe I've ever turned a wrench on a '77 Regal, but can you loosen any other component to take the tension off the belt? Thanks for watching!

[@dolittle6781]

@@erikstrawn3885 Thanks. I’ll see which components I can loosen. Didn’t want to deal with the tensioner if I didn’t have to.

[@jacobcallahan4813]

Thank you for your help, tried asking one of the groups im in about how to fix/work on these old cars since i wasn't born in the 70s and all i got was beratement and belittling responses

[@erikstrawn3885]

You're welcome! When you get to be the old, grumpy guy, please remember this and take the time to teach. Thanks for watching!

[@williamrosenow6176]

I have a Buick book from 1966. I think it is a half inch at 15 pounds of pull on a spring scale. Nothing in the old days was accurate like now so tighten and put firm pressure on the belt with one finger, if it looks like half inch you're good. V-belt would balloon at high RPM so a built engine needed to be tighter but the bearings sucked so the guys who drag raced would only have the belt that ran the water pump and fan while racing then put the alternator belt on to drive home.

[@erikstrawn3885]

Belt driven fans didn't help. I had a dual-sheave pulley on my RX-7 to help keep the belt from slipping at 9,000 rpm. I ditched the clutch fan for electric and immediately solved that problem. Thanks for watching!

[@williamrosenow6176]

I was talking about a chevy 396 rebuilt in the early 90s. They didn't do electric because it was new. I know what we can do now is better but the old guys wanted to do it their way. My brother had a 1990 Camero and I had a 1982 280zx so I had the modern car. My dad had the 1966 chevelle with the 396 that couldn't keep up with either. I like the old car sound and look but they couldn't keep up with a KIA.@@erikstrawn3885

[@PJ-qx5yt]

100% just get a krikit

[@erikstrawn3885]

That's $25 I don't have to spend because I spent a little time learning the proper feel for a belt. But, yes, if you're working on a system that requires a very specific belt tension, a belt tension gauge is worth it. Thanks for watching!

[@gonzogilberto4690]

Thank you brother

[@erikstrawn3885]

You're welcome. Thanks for watching!

[@kieranthomas5478]

Just fitted one on mine maybe done bit tight.. wouldn't really be able to twist mine like that and I'm getting squeak 😮

[@erikstrawn3885]

Interesting. New belt? Correctly sized in length and width? All accessories turn freely? Pulleys aligned correctly?

[@massimomeridio1892]

Interesting questions...i have got the same problem here,i noticed that a oversized belt,wich doesnt fit prpwrly in the channel helps to keep the squeeking but tha i realized its just becouse its a very old one its just slipping quietely...so now i thought to put the right size one and spry some silicone but i dont know what i am dosing basically

[@kieranthomas5478]

I've realised what my problem was didn't tighten the tensioner tighter enough. My belt was as tight as the one in video but was still to loose tightened it so belt pushed down quarter of inch in middle and was perfect.

[@kieranthomas5478]

Not had any issues since with screeching thank god was embarrassing 😂

[@erikstrawn3885]

@@kieranthomas5478 Apologies that I didn't see your responses until now. I'm glad you found the issue. Thanks for watching!

[@nickl2548]

Brilliantly explained and demonstrated

[@erikstrawn3885]

Thanks! These tips aren't getting passed on to younger techs and I'm hoping to give back a little of what my mentors taught me. Thanks for watching!

[@Maplecook]

I just installed a new alt on my car 2 days ago. After viewing this vid, I suspect that I may have installed the belt too tight. The car ran normally for 2 days, but upon intial start up, it did squeal for like a second. Tonight, the battery light came on intermittently, for the last 2 miles home. Popping the hood, I checked the battery terminals: solidly tight. The battery is BRAND new, too. I did notice a faint burning rubber smell, coming from right over my alt. So, did I just fry up my brand new alt, or, do you think I can still save this, by loosening that belt?

[@erikstrawn3885]

You can loosen and retighten the belt, but if you hurt your alternator by having the belt too tight, you wouldn't fry the electrics, you'd damage the bearings. While you have the belt off, spin the alternator and make sure it's smooth and not crunchy. If the alternator and battery are both new and your battery is still dying, make sure your battery connections are both clean and tight. Then check for a parasitic draw - I don't have a video for that yet, but I need to do one. Thanks for watching!

[@Maplecook]

@@erikstrawn3885 Thank you so much for your advice, Mr. Strawn. I can't afford a trip to the shop, so you're really helping me out here. Okay, if I understood you right, if the alt and battery are good, and the connections are clean and tight, you said to look for a, "parasitic draw." What is that, exactly? The wire from the battery to the alt? Sorry for the noob-level questions.

[@Maplecook]

@@erikstrawn3885 Good to know that I didn't fry the electrics. So, that faint burning rubber smell, it probably came from some melted wire somewhere else in the vicinity? Also, I only drove the car about 2 miles with the intermittent flickering of the battery light on, so am I safe to assume that even if I was hard on that bearing, that it's still probably okay, so long as I loosen the belt? I'll use your 90 degree trick to determine belt tightness. Thank you for your time. =)

[@erikstrawn3885]

@@Maplecook Your alternator should be fine. I think your problem is elsewhere. I haven't done a video on parasitic draw, but I need to. It's a fairly simple way to quickly narrow down to a specific circuit if something is "staying on" when the key is off. Basically, pull your fuses and use a test light to see if the current through each fuse socket is enough to light the test light.

[@Maplecook]

@@erikstrawn3885 Thank you!