in the absence of a video, how can any of us tell?

if it is your tensioner for the timing belt, you're playing with fire by continuing to run the engine.

if the timing belt jumps or comes off, thats the end of your motor.

do a search here for timing belt tensioner failures and watch some of the videos, if the sound is similar you have your answer.

 

Did you or the previous owner use OEM parts? The serpentine belt tensioner and belt may have issues if not OEM. Also timing belt and tensioner.

 

Agree, non-OEM serpentine belts can cause noise. And non-OEM serpentine tensioners are usually junk right out of the box.

You can remove the serpentine belt and run the engine briefly. If the noise is still there, then TB tensioner and/or idler pulley can’t be ruled out. If noise is gone, you’ll have to narrow it down from the serpentine belt train components. Stethoscopes can help track the noise down.

 

doesnt sound like your timing belt tensioner, more likely something in the drive belt line.

Have you noticed if the noise is more pronounced with the HVAC system turned off?

My compressor makes that rattling from the clutch while its operating.

Its been doing it for 3+ years, and I wont be fixing it until it completely fails.

 

TB tensioner failure usually just causes rattle at cold starts but then gets better after 30 sec or so. Of course it could last longer if the failure was let go for a long time.

I concur with @2011.2017.odyssey suggestion that the compressor clutch is noisy...probably a failed bearing. Mine does this occasionally and I have not yet got around to replacing it.

 

Here was mine when it failed last year. It did it for about a minute when cold. If thats what it is absolutely avoid driving it, the belt could slip a few teeth at any time and brick your engine.

You can inspect it without taking too much apart. Look for fluid leak.

(Note it WAS loud, but not as loud as the video makes it appear. Good mic on the phone I guess)

 

YES! I just fixed this last night. This was the culprit. I have before and after video of the engine sound. Sounds good as new, I was ready to scrap the whole thing.

 

Wow that old tensioner was apparently at the very end of life! They usually only make noise at startup! It's great that you fixed it before the whole thing blew up!

Edit: I thought this was the OP when I replied! I'm not sure how long @Ody.hulk noise lasted after startup, but the OP's noise seemed to persist longer.

 

in the absence of a video, how can any of us tell?

if it is your tensioner for the timing belt, you're playing with fire by continuing to run the engine.

if the timing belt jumps or comes off, thats the end of your motor.

do a search here for timing belt tensioner failures and watch some of the videos, if the sound is similar you have your answer.

I've got a 2014 EX-L with about 150k miles on it. I have started noticing the past couple weeks a little rattling noise seeming to be coming from the serpentine belt area. Mainly noticeable at idle but also when coasting down to a stop. Today it seemed much louder than earlier in the week.

It's been a bit slow to crank some days in the heat (live in Indiana) but otherwise no other problems with it. Bought it used at 138k and the timing belt was done around 100k and only a few years ago if memory serves, I'll have to check my records.

I'm fairly sure it's not the serpentine belt tensioner or pulleys - I just changed the alternator last month and didnt see anything amiss while working in that area for a while.

What are your thoughts? Could this be something other than the tensioner? It's not been that long since belt service but I didn't own it and dont know for sure the service details.

Edit: I have a video but cant upload it from my phone due to size going to try to do it in the morning
Video link:

I think it's your tension spring in the serpentine belt tension/idlers. I thought in the video I could see the tensioner bouncing a little. Replaced my 2012 tensioner a few weeks back at 170k. Quieted right down.

I've got a 2014 EX-L with about 150k miles on it. I have started noticing the past couple weeks a little rattling noise seeming to be coming from the serpentine belt area. Mainly noticeable at idle but also when coasting down to a stop. Today it seemed much louder than earlier in the week.

It's been a bit slow to crank some days in the heat (live in Indiana) but otherwise no other problems with it. Bought it used at 138k and the timing belt was done around 100k and only a few years ago if memory serves, I'll have to check my records.

I'm fairly sure it's not the serpentine belt tensioner or pulleys - I just changed the alternator last month and didnt see anything amiss while working in that area for a while.

What are your thoughts? Could this be something other than the tensioner? It's not been that long since belt service but I didn't own it and dont know for sure the service details.

Edit: I have a video but cant upload it from my phone due to size going to try to do it in the morning
Video link:

I've got a 2014 EX-L with about 150k miles on it. I have started noticing the past couple weeks a little rattling noise seeming to be coming from the serpentine belt area. Mainly noticeable at idle but also when coasting down to a stop. Today it seemed much louder than earlier in the week.

It's been a bit slow to crank some days in the heat (live in Indiana) but otherwise no other problems with it. Bought it used at 138k and the timing belt was done around 100k and only a few years ago if memory serves, I'll have to check my records.

I'm fairly sure it's not the serpentine belt tensioner or pulleys - I just changed the alternator last month and didnt see anything amiss while working in that area for a while.

What are your thoughts? Could this be something other than the tensioner? It's not been that long since belt service but I didn't own it and dont know for sure the service details.

Edit: I have a video but cant upload it from my phone due to size going to try to do it in the morning
Video link:

I've got a 2014 EX-L with about 150k miles on it. I have started noticing the past couple weeks a little rattling noise seeming to be coming from the serpentine belt area. Mainly noticeable at idle but also when coasting down to a stop. Today it seemed much louder than earlier in the week.

It's been a bit slow to crank some days in the heat (live in Indiana) but otherwise no other problems with it. Bought it used at 138k and the timing belt was done around 100k and only a few years ago if memory serves, I'll have to check my records.

I'm fairly sure it's not the serpentine belt tensioner or pulleys - I just changed the alternator last month and didnt see anything amiss while working in that area for a while.

What are your thoughts? Could this be something other than the tensioner? It's not been that long since belt service but I didn't own it and dont know for sure the service details.

Edit: I have a video but cant upload it from my phone due to size going to try to do it in the morning
Video link:

I think it's your serpentine idler assembly. There is a little bounce in the vid

 

I've got a 2014 EX-L with about 150k miles on it. I have started noticing the past couple weeks a little rattling noise seeming to be coming from the serpentine belt area. Mainly noticeable at idle but also when coasting down to a stop. Today it seemed much louder than earlier in the week.

It's been a bit slow to crank some days in the heat (live in Indiana) but otherwise no other problems with it. Bought it used at 138k and the timing belt was done around 100k and only a few years ago if memory serves, I'll have to check my records.

I'm fairly sure it's not the serpentine belt tensioner or pulleys - I just changed the alternator last month and didnt see anything amiss while working in that area for a while.

What are your thoughts? Could this be something other than the tensioner? It's not been that long since belt service but I didn't own it and dont know for sure the service details.

Edit: I have a video but cant upload it from my phone due to size going to try to do it in the morning
Video link:

I think it's your serpentine idler. The spring has failed. There is a little bounce in the video. I did mine a few weeks ago on my 2012 at 170k.

 

Mechanics stethoscopes are a very low cost tool and are great for finding the source of noise. Diagnosis over internet for this type issue is typ difficult.

First check if oem parts were used at 100k TB work. Check if TB tensioner was changed at that time.
If its a honda oem tensioner and belt then you could consider just doing the tensioner.

DanaH

 

Here, just made this video, you can hear the sound before and after replacing the tensioner.

 

Sounds just like mine did when the TB tensioner failed. The sound lasted about 30 sec on cold starts only.

 

I've got a 2014 EX-L with about 150k miles on it. I have started noticing the past couple weeks a little rattling noise seeming to be coming from the serpentine belt area. Mainly noticeable at idle but also when coasting down to a stop. Today it seemed much louder than earlier in the week.

It's been a bit slow to crank some days in the heat (live in Indiana) but otherwise no other problems with it. Bought it used at 138k and the timing belt was done around 100k and only a few years ago if memory serves, I'll have to check my records.

I'm fairly sure it's not the serpentine belt tensioner or pulleys - I just changed the alternator last month and didnt see anything amiss while working in that area for a while.

What are your thoughts? Could this be something other than the tensioner? It's not been that long since belt service but I didn't own it and dont know for sure the service details.

Edit: I have a video but cant upload it from my phone due to size going to try to do it in the morning
Video link:

Remove the belt and start the engine! If the noise is gone, check pulley and tensioner.If the noise is still there, turn the engine off immediately!

 

I have a 2013 and have had 2 OEM TB tensioners go bad on me prematurely. First was replaced by dealer free at 60k miles and OEM part used. That tensioner went bad about 75k miles later. I replaced it and the belt and water pump with an Aisin kit. TB tensioner made a lot of racket at the first cold start of the day, then calmed down after about 30 seconds.

 

I've got a 2014 EX-L with about 150k miles on it. I have started noticing the past couple weeks a little rattling noise seeming to be coming from the serpentine belt area. Mainly noticeable at idle but also when coasting down to a stop. Today it seemed much louder than earlier in the week.

It's been a bit slow to crank some days in the heat (live in Indiana) but otherwise no other problems with it. Bought it used at 138k and the timing belt was done around 100k and only a few years ago if memory serves, I'll have to check my records.

I'm fairly sure it's not the serpentine belt tensioner or pulleys - I just changed the alternator last month and didnt see anything amiss while working in that area for a while.

What are your thoughts? Could this be something other than the tensioner? It's not been that long since belt service but I didn't own it and dont know for sure the service details.

Edit: I have a video but cant upload it from my phone due to size going to try to do it in the morning
Video link:

might be the spindle. it seems to be rotating unevenly in its cycling.
i'm an oddball in that i can detect dissynchrony in hypercycles.
...harmonics & all. i can perceive the cycles in lighting,(&accoustics) & many fluorescents gave me migraines accordingly.
its more like a high rpm chattering going on. probably not bearings tho.

 

I went through this a while back, had changed just the idler and tensioner pulleys (Honda parts) but used an aftermarket belt when I replaced my alternator.

After the rattle started I ordered a new Honda belt tensioner assy(ordered for Amayama, was half the cost of everywhere I normally buy OEM Honda parts) but really wasn’t sure that was it.

Because of a thread I found on here about non-Honda belts causing the problem, I switched to a Honda belt while waiting for the tensioner to arrive and the rattle went away, but only for about a week, then started again.

At this point I’m driving myself crazy trying to figure this out and I convinced myself that it was almost 100% the A/C compressor clutch bearing.

I took it over to my trusted Honda mechanic in town and he listened and he said “I’m almost 100% you DON’T need an A/C clutch, it’s your belt tensioner assembly”, so I went home and put the tensioner on and no more noise.

long story short: I wish I didn’t hear things sometimes and I wish I was like other people and not obsessive about fixing things that rattle, I would be a happier person. 🤣

 

...Long story short: I wish I didn’t hear things sometimes and I wish I was like other people and not obsessive about fixing things that rattle, I would be a happier person. 🤣

 

I would rather be paranoid about a rattle than weeping over a dead engine.