Threw my serpentine belt today

[Elkins45]

I was about 12 miles from home on a secluded rural road driving my 2016 Mazda6 with 75k miles. I had stopped about five miles before so my wife could run into the store, so although I had been driving for an hour previously it had just recently been started again. Suddenly I felt the AC turn hot. It’s close to 100° today so we noticed pretty quickly. I glanced down to see the battery light was on. I’ve seen this once before when an alternator failed, but a battery light combined with dead AC made me correctly guess either the belt had broken or the computer knew it wasn’t charging and disabled the AC. There was no indication of overheating. Fortunately I have a new battery, and the water pump is driven by a separate belt on this car, so we managed to make it home without it dying.

When I popped the hood I saw the serpentine belt was still in the engine compartment but was off the alternator and compressor. It was too hot to reach down and check if it is still intact, but eight years and 75k is really early for a belt failure. I’m thinking the tensioner must be failing and that's what let it jump the pulleys. The hydraulic tensioners for these years are known for failing early around 60k. Time to spend some money I guess.

 

[bdcardinal]

Not uncommon for me to quote out the tensioner and both belts on these.

 

[BrendanC]

i refuse to run any belt past 50k due to this. texas heat doesn’t play well with belts/pulleys. every consumable pulley and belt gets replaced at 50k intervals with the tensioner getting two pulleys total before changing it.

 

[Dave Hess]

Not uncommon for me to quote out the tensioner and both belts on these.

How much for everything ?

I got a 2018 CX5 that just hit 100K miles.

 

[Elkins45]

Not uncommon for me to quote out the tensioner and both belts on these.

Do you go through the wheel well or do you jack up the engine and remove the motor mount? I’ve seen videos of people doing it both ways.

 

[bdcardinal]

Do you go through the wheel well or do you jack up the engine and remove the motor mount? I’ve seen videos of people doing it both ways.

I do parts, but I will ask our Mazda guy tomorrow at work.

 

[Cruisin'n5thgear]

Guess I got lucky running to around 150k miles, but I think the tensioner was leaking. Belt definitely needed replacement, and it's been driven in moderate climates (NJ/MS/DE).

 

[JWC86]

I try to be proactive about changing belt now after about 6 years ago I was in the Northwest British Columbia about 300miles from any decent population center and about 100miles from anything that resembles a town.

The road I was on maybe gets as little at 2-3 trucks a day. Temp was -32C. Zero cell service.

Coming out from a job, get all the symptoms of belt gone: no power steering, charging, etc… well crap

Truck was a 2015 GMC 3500 6.0L, maybe 75,000 miles on it at the time but probably 3000 hours.

I was lucky to have another belt but it was in the jockey box out back so it was -32C and stiff as a board. Things were cooling off quick so I put on all my winter gear and shoved the belt down inside my coat while I got my tools out. For anyone that has worked in these temps you know the struggle that some simple tasks can be. Like trying to open a frozen tool box with gloves on, ratchet won’t ratchet, etc.

Lucky for me the engine bay inside that truck with the 6.0L had lots of room in front of the engine to access the belt. I wasn’t thinking strait as I did have a small amount of panic setting in due to the struggle I was having, not an easy job to do when you can’t feel your hands. I couldn’t find a routing diagram anywhere although I later noticed it was right there on the inside of the hood haha.

Anyways, ever since that experience I change my belt, pulley and tensioner proactively.

 

[KrisZ]

I mean failures can definitely happen all of the sudden, but generally speaking 100k miles is rather standard interval for accessory belts.

I posted how the belt on my Dodge looked like just shy of 100k and I was surprised how many BOTOGers chimed in with their belts at 150k+ miles on them. Kind of surprised me people let these go that long.

 

[Elkins45]

The dealer I bought it from quoted $224 for the tensioner. Fortunately I found a Mazda dealer in Cincinnati who sells parts online. The tensioner and both belts ended up costing $198 with tax. Given how cramped everything is I may pay a professional to install it.

 

[bdcardinal]

How much for everything ?

I got a 2018 CX5 that just hit 100K miles.

2.0 or the big block 2.5?

 

[Dave Hess]

2.0 or the big block 2.5?

2.5

Sorry for late reply I was out of town.

 

[Elkins45]

So it turns out the old belt was actually broken, so I might have replaced a working tensioner. Labor was a very reasonable $85, so I paid twice as much for the parts as it cost to have them installed.

I think I might need to put a set of aftermarket spares in the trunk if they only last eight years or 75k miles.

 

[BrendanC]

So it turns out the old belt was actually broken, so I might have replaced a working tensioner. Labor was a very reasonable $85, so I paid twice as much for the parts as it cost to have them installed.

I think I might need to put a set of aftermarket spares in the trunk if they only last eight years or 75k miles.

i always go for green gates fleet runner belts. might have to do some catalog look up to find it however.

 

[JimPghPA]

Some vehicles have a combination main drive pulley and harmonic ballancer all in one with rubber (usually black) between the inner section and the outter section. These can go bad from rubber degrading. When they do the outter section with weight and pulley drive becomes un-aligned and it throws the belt.

So examine that drive pulley very well. If it looks like a 2 part and unaligned replace it. If you don't the new belt won't stay on long.

 

[spasm3]

So it turns out the old belt was actually broken, so I might have replaced a working tensioner. Labor was a very reasonable $85, so I paid twice as much for the parts as it cost to have them installed.

I think I might need to put a set of aftermarket spares in the trunk if they only last eight years or 75k miles.

I'd wait and buy a fresh one closer to when you would change it out.

 

[VersatileGuy]

Yes, I have dealt with a belt that is about 14 years old and probably 150k. That's an aftermarket Bando for Toyota.

But you or someone in a shop need to check periodically. Your failed belt might have had squealing, excessive play, cracking, oil, or excessively deep grooves, those are signed it's going out.

Mazda might be partnering with Toyota now, but their cars are not built as durable.

 

[researcher]

And 8 years and 75k miles before it failed, used to be a winner. I'd still say I wouldn't run any drivebelt longer than 50k miles but I replace stuff early.

 

[bdcardinal]

2.5

Sorry for late reply I was out of town.

Tensioner is the same for both engines, 197.99
The water pump belt is 22.25
The serp belt is 46.37

 

[Elkins45]

And 8 years and 75k miles before it failed, used to be a winner. I'd still say I wouldn't run any drivebelt longer than 50k miles but I replace stuff early.

I think that’s a winning plan going forward. It’s much better to replace one in the driveway with the tensioner tool than trying to do it with a socket on the side of the road somewhere.