Noise Diagnosis

[mmeuli]

Got this noise coming from the alternator-ish area. I pulled the belt this weekend--no frays or signs of wear were on it. Each pulley rotated freely without noise or any signs of wear. Can't figure out what's wrong--the sound appears to be coming from the alternator, but it's working properly.

Any armchair QBs willing to toss in some free, unsolicited advice?

Here's a link to the issue:

5th gen 4runner noise - YouTube

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[mteolus]

That's a strange one. Maybe the tensioner pulley bearing is wearing out? Doesn't sound like a manifold exhaust leak but you never know.

 

[mcat707]

A mechanics stethoscope could help with pin pointing the noise.

They’ve worked for me when looking for noises.

Amazon.com: Powerbuilt 640582 Mechanic's Stethoscope: Automotive

 

[sarahk99]

A mechanics stethoscope could help with pin pointing the noise.

They’ve worked for me when looking for noises and average sat score coudl be important

Amazon.com: Powerbuilt 640582 Mechanic's Stethoscope: Automotive

to be honest I think that you need to be a professional to use one of those!

 

[TOYO74]

IMO sounds more like valve train noise at idle. Does the sound quit or get louder when you rev the engine?

 

[fkheath]

IMO sounds more like valve train noise at idle. Does the sound quit or get louder when you rev the engine?

I agree -- the clicking sounds like valve train, not a bearing. Also, if the clicking gets faster as you rev the engine would also point to valve train.

 

[mmeuli]

I agree -- the clicking sounds like valve train, not a bearing. Also, if the clicking gets faster as you rev the engine would also point to valve train.

I can't hear it when revving the engine. I can't tell if it softens the sound or the engine revving just masks it.

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[Jivewalker]

Honestly, to me it sounds normal. I can't hear anything that sounds off. All the ticking and tapping sounds just like mine. Oh, and hello fellow chucktownian.

 

[progress4m]

Got this noise coming from the alternator-ish area. I pulled the belt this weekend--no frays or signs of wear were on it. Each pulley rotated freely without noise or any signs of wear. Can't figure out what's wrong--the sound appears to be coming from the alternator, but it's working properly.
...

Was the noise gone after you removed the belt..? or removing the belt had no affect on the noise?

 

[mcat707]

to be honest I think that you need to be a professional to use one of those

Thank you for the compliment. I didn’t know I reached professional status. All I need now is a Dickies button up shirt with the sleeves cut off and my avatar name sewn on a embroidered patch on my chest to match my dirty finger nails.

 

[mmeuli]

Was the noise gone after you removed the belt..? or removing the belt had no affect on the noise?

No effect. I happened to just change my oil and based on other threads it might be the Mobil1 HM that I used. Too cheap to buy more oil, so I'll use a different type next go round.

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[mmeuli]

Honestly, to me it sounds normal. I can't hear anything that sounds off. All the ticking and tapping sounds just like mine. Oh, and hello fellow chucktownian.

Cheers!

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[mmeuli]

No effect. I happened to just change my oil and based on other threads it might be the Mobil1 HM that I used. Too cheap to buy more oil, so I'll use a different type next go round.

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I stupidly misread your question. Once reason prevailed, i removed the belt and ran the engine, rather than removing, reattaching, and running it.

The sound disappears with the belt removed. Truly can't find a bad pulley though--they spin freely, no noise, and no visible wobble.

Guess i should replace them one by one but really hate to do that. Any suggestions on Diagnosis?

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[mmeuli]

Was the noise gone after you removed the belt..? or removing the belt had no affect on the noise?

Here's a video of it without the belt. 5th gen 4runner with serpentine belt removed - YouTube

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[progress4m]

Here's a video of it without the belt. 5th gen 4runner with serpentine belt removed - YouTube

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Well… based on that video the noise is completely gone, so clearly it is related to belt\accessories and not the engine (internals) itself and that is obviously the good news!

Finding what accessory is making the noise can be tricky... and that is why you hear about many stories when dealer\shop replaces all pullies and alternator all in once as they cannot pinpoint the culprit… using stethoscope or a long shaft screwdriver may help a lot so I would start with that, spraying lubricant into the bearing\shaft area of each pulley is another “trick” you can try, same goes for spraying the “belt dressing” on the belt (especially if the belt is old and you will be replacing it soon anyway)…

As an additional thought, after listening your original “video with the noise” couple more times, I feel like the noise is coming from the fan area… so I would check the fan itself (with the belt removed) and make sure it spins freely, the fan itself is not cracked and not touching anything (like a fan shroud)… if everything ok with the fan itself, then it could be water pump… and with that level of the noise you should “feel” it by turning the fan pulley with belt removed…

How many miles are on the truck?

 

[mmeuli]

Well… based on that video the noise is completely gone, so clearly it is related to belt\accessories and not the engine (internals) itself and that is obviously the good news!



Finding what accessory is making the noise can be tricky... and that is why you hear about many stories when dealer\shop replaces all pullies and alternator all in once as they cannot pinpoint the culprit… using stethoscope or a long shaft screwdriver may help a lot so I would start with that, spraying lubricant into the bearing\shaft area of each pulley is another “trick” you can try, same goes for spraying the “belt dressing” on the belt (especially if the belt is old and you will be replacing it soon anyway)…



As an additional thought, after listening your original “video with the noise” couple more times, I feel like the noise is coming from the fan area… so I would check the fan itself (with the belt removed) and make sure it spins freely, the fan itself is not cracked and not touching anything (like a fan shroud)… if everything ok with the fan itself, then it could be water pump… and with that level of the noise you should “feel” it by turning the fan pulley with belt removed…



How many miles are on the truck?

145,000. I'll give it a whirl tomorrow. Used a ratchet and funnel on the pulleys i could safely touch. Honestly the alternator was audibly louder than anything else... Which tbh was what i originally thought it was coming from. But no issues with the alternator itself. Autozone said the alternator is sold with the pulley attached--that is that the pulley wasn't sold by itself or able to be replaced. I'm going to do what you suggested and if those things are fine, I think I'll see if i can't explore the alternator pulley more.

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[mmeuli]

Well… based on that video the noise is completely gone, so clearly it is related to belt\accessories and not the engine (internals) itself and that is obviously the good news!



Finding what accessory is making the noise can be tricky... and that is why you hear about many stories when dealer\shop replaces all pullies and alternator all in once as they cannot pinpoint the culprit… using stethoscope or a long shaft screwdriver may help a lot so I would start with that, spraying lubricant into the bearing\shaft area of each pulley is another “trick” you can try, same goes for spraying the “belt dressing” on the belt (especially if the belt is old and you will be replacing it soon anyway)…



As an additional thought, after listening your original “video with the noise” couple more times, I feel like the noise is coming from the fan area… so I would check the fan itself (with the belt removed) and make sure it spins freely, the fan itself is not cracked and not touching anything (like a fan shroud)… if everything ok with the fan itself, then it could be water pump… and with that level of the noise you should “feel” it by turning the fan pulley with belt removed…



How many miles are on the truck?

Definitely the alternator. Grabbed a cheap stethoscope and it's quiet on the valve cover and other pulleys but it sings on the alternator. Can that pulley be removed without replacing the entire alternator?

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[progress4m]

Definitely the alternator. Grabbed a cheap stethoscope and it's quiet on the valve cover and other pulleys but it sings on the alternator. Can that pulley be removed without replacing the entire alternator?

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There is no “pulley” on the alternator, it is just a grooved wheel pressed into the alternator’s shaft and if you have pinpointed that as a source of the noise then what you hear is a bad\ falling bearing (s) in the alternator.

That alternator needs to be replaced or repaired... there are no other way to fix this.

 

[mmeuli]

There is no “pulley” on the alternator, it is just a grooved wheel pressed into the alternator’s shaft and if you have pinpointed that as a source of the noise then what you hear is a bad\ falling bearing (s) in the alternator.

That alternator needs to be replaced or repaired... there are no other way to fix this.

I found the FSM online. It has a clutch pulley that can be removed and troubleshot. Searched for the SSTs (Special Service Tool) needed: the wrench is $500 and the puller set is $1400. What a joke! Going to try to find a workable universal set and might do a write up if I can.

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[DougR]

I'm not 100% certain you have a clutch pulley on your alternator. The manual shows a clutch pulley, however, that particular part appears to be a simple pulley when I look up the part for my 2011 Trail: 2009-2020 Toyota Alternator Pulley 27415-0W131 | Camelback Toyota Parts See this discussion Alternator output? One YouTube video appears to show a simple pulley, but that could have been an aftermarket alternator. Have you verified you have a clutch pulley? Given the price $82.34, it should be a clutch pulley.

If you need a clutch pulley tool, Malcolm put up a positive review on this tool set Amazon.com: Customer reviews: Gates 91024 Alternator Decoupler Pulley Tool Kit with Case after Gates replaced one of the wrenches that broke on the first attempt to disassemble. Gates has an excellent video on diagnosis and repair using their tool set: GATES TRAINING: Alternator Decoupler Pulley - How to Inspect and Replace (full version) - YouTube

If you have a clutch pulley, have you attempted to test it with the alternator on the vehicle? Remove the belt and rotate pulley back and forth to test it. You might have to hold a small screwdriver against a cooling fin to keep the core from rotating. If the clutch pulley failed and the alternator bearing is OK, Gates recommends replacing the serpentine belt, tensioner and clutch pulley at the same time. Your belt and tensioner might be OK if the problem is fixed soon enough to avoid exposing those parts to excessive torsional vibrations.