Insanely tight serpentine belt?

[Avery4]

Hello everyone, I just got done changing an alternator on my friend's 2015 Chevy Sonic 1.8 because the bearings failed and was causing it to make a very loud rumbling noise literally less than 1000 miles after the warranty was up. Nice. Anyways, I was surprised by the amount of tension on that serpentine belt when I took it off. That belt tensioner was TIGHT. I wasn't able to get it to budge at all with a standard length 19MM wrench, I needed to use another wrench over the end of that one in order to barely get enough leverage to pull the tensioner back enough get the belt off, and it was still extremely difficult. The belt is so tight that I was unable to push it down more than about 1/8 of an inch. I have replaced several belts and I have never felt nearly that much tension on a belt.

So my question is if there could be something wrong with the belt tensioner that is causing it to way overtension the belt and destroy the alternator, I know too much tension can destroy bearings in the accessories. I don't see how a spring loaded tensioner could do that, but I also can't imagine that they would design the tensioner to tighten the belt so ridiculously tight either. Is this something I should be worried about, or is that normal for some cars? Thanks in advance, I would hate for the new alternator or another accessory to be destroyed by the belt tensioner if it's bad.

 

[slo town]

Our BMW E90 has an INSANELY tight tensioner. I needed an 18 inch breaker bar to R&R the belt. At 90k miles all accessories and bearings are fine.

FWIW,

Scott

 

[JustinH]

Both Toyota ones I did were very tight. Used a breaker bar style tensioning tool, and gloves with my hand wrapped in a towel.

 

[vw7674]

Somewhere in the past I learned rubber does contract slightly with heat.
So a super tight belt at ambient temp would only get tighter when underhood temps climb to operational norms.
I did see the results of that with an over-tensioned timing belt tension bearing once, grease was cooked out,
bearing seized solid & the roller was serving as a rubbing block. A groove was forming on the outside of the T-belt from the seizure.

 

[zzyzzx]

The belt is probably too short.

 

[Avery4]

Originally Posted by zzyzzx
The belt is probably too short.

I replaced the belt because it was starting to crack when I replaced the alternator and the new belt was just as tight, so unless they sold my friend another belt that's too short that's not it. Good thought though!

 

[Hall]

Does the tensioner have range markings ? I'd try asking this question in a Sonic-specific forum in case you don't get much Sonic-specific responses. Maybe their tensioners are very "tight" by design. Maybe there's a known issue of a bad batch of tensioners that tighten the belts too much, wear out bearings, etc.

 

[Avery4]

Originally Posted by vw7674
Somewhere in the past I learned rubber does contract slightly with heat.
So a super tight belt at ambient temp would only get tighter when underhood temps climb to operational norms.
I did see the results of that with an over-tensioned timing belt tension bearing once, grease was cooked out,
bearing seized solid & the roller was serving as a rubbing block. A groove was forming on the outside of the T-belt from the seizure.

That's probably true that the belt gets tighter as it heats up, from my experience when a belt with a manual tensioner is loose it often stops slipping once it heats up. I have heard that temp fluctuations is one of the reasons why more and more cars have automatic spring loaded tensioners rather than manual tensioners, along with making belt installation more idiot proof since the installer no longer has the ability to over or under tension the belt and either cause it to slip or destroy accesories.

My car has a manual belt tensioner with a wing nut that is tightened or loosened to adjust belt tension, which I like because it makes getting the belt on or off much easier since I don't have to hold the tensioner back while I get the belt on. I install the belt as loosely as I can without it slipping to minimize stress on the alternator and AC compressor bearings.

 

[SHOZ]

My '08 Hyundai Accent ha a serp belt for the water pump/alternator. I set the tension at the highest voltage. It's about a 1/4 flex on the belt when twisted.

 

[Avery4]

Originally Posted by hallstevenson
Does the tensioner have range markings ? I'd try asking this question in a Sonic-specific forum in case you don't get much Sonic-specific responses. Maybe their tensioners are very "tight" by design. Maybe there's a known issue of a bad batch of tensioners that tighten the belts too much, wear out bearings, etc.

Great advice, thank you. I didn't see any markings on the tensioner. It might just be tight by design, I could be worrying about nothing. However, the bearings in the alternator failing at 60K miles along with more belt tension than I have ever seen before concerns me. In my opinion that alternator should not have failed so early, something caused it to fail. Whether it failed because it was simply defective or because of another factor such as an overtightened belt is the question.

 

[bulwnkl]

The J35 in my Honda Ridgeline had an INSANELY tight serp belt when I changed it along with the timing belt & water pump recently. Loosening the tensioner as far as it would go still left me _almost_ unable to get that serp belt on. Haven't seen any ill-effects from the first 105k miles. Hopefully won't see any from the next 100 - 150k.

 

[Avery4]

Originally Posted by bulwnkl
The J35 in my Honda Ridgeline had an INSANELY tight serp belt when I changed it along with the timing belt & water pump recently. Loosening the tensioner as far as it would go still left me _almost_ unable to get that serp belt on. Haven't seen any ill-effects from the first 105k miles. Hopefully won't see any from the next 100 - 150k.

Thanks. If the tension on that belt is anything like on the K24's, it's way tighter than that. I have done belts on Accords and CRVs with the K24 engine and the tensioner felt tight, but not anywhere near as tight as the tensioner on my friend's Sonic. Why do they design the tensioners to tighten the belts so ridiculously tight anyways? I know from previous experience with manual tensioners that the belt doesn't need to be anywhere near that tight to not slip, and if the belt isn't slipping there is no benefit to going any tighter. Thanks

 

[Amkeer]

The belts should have flex in them and not too tight. I just changed mine on the Tacoma and my Tundra and they were within spec on the flex of the belt. If they are too tight it will cause bearing issues among other things.

 

[Lubener]

Over time, the pivot (not pulley) for the tensioner starts to bind up and does not move freely. Maybe the belt was the wrong one on the vehicle.

 

[nutdriver]

I would definitely check the tensioner to make sure that it's moving freely. I had this exact scenario on another vehicle and it turned out to be the tensioner.

 

[The Critic]

Originally Posted by bulwnkl
The J35 in my Honda Ridgeline had an INSANELY tight serp belt when I changed it along with the timing belt & water pump recently. Loosening the tensioner as far as it would go still left me _almost_ unable to get that serp belt on. Haven't seen any ill-effects from the first 105k miles. Hopefully won't see any from the next 100 - 150k.

Thanks. If the tension on that belt is anything like on the K24's, it's way tighter than that. I have done belts on Accords and CRVs with the K24 engine and the tensioner felt tight, but not anywhere near as tight as the tensioner on my friend's Sonic. Why do they design the tensioners to tighten the belts so ridiculously tight anyways? I know from previous experience with manual tensioners that the belt doesn't need to be anywhere near that tight to not slip, and if the belt isn't slipping there is no benefit to going any tighter. Thanks

K24's are fairly loose imo. The J35's that use the hydraulic tensioner can be difficult to compress without the SST.

 

[Silver]

My '02 Taurus has a very tight belt. Replaced tensioner and belt, same tight fit. The belt has to be forced over the alternator pully even with the tensioner at full compression.

 

[DGXR]

I would check the wear marks on the belt tensioner to be sure it's in the correct range. All belt tensioners have marks indicating if the belt is stretched. Generally it seems like a bad idea to have an accessory belt that is so very tight. I suppose it might be necessary if the belt has a short arc around a compressor or other pulley that gives big resistance, but in that case, the extra tension is just compensating for a poor accessory drive design.