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Right around 105K miles (not sure exactly) I got the maintenance code for a timing belt change. I installed the Aisin kit, a genuine one from a reputable retailer, along with a new Honda branded passenger side engine mount, and used all new bolts for the timing belt tensioner and new bolts for the pulleys. I got everything installed and it runs great, however I hear a faint whirring noise at low RPM. It increases in frequency with RPMs up to about 2000 or so and any higher than that I can't hear it. It's most noticable at low idle. I can't hear it at all outside the car and can't even hear it with my head a few feet from the timing area with the hood open, however it's really noticeable inside the cabin and it bothers me especially since I didn't hear it before. The sound also seems to go away once the engine is nice and warmed up. I can go on a long trip and after I stop it sounds like a normal idle without this whirring sound.

It's not the alternator, AC, or power steering since I removed the accessory belt and the sound is still present. It also doesn't sound like the typical alternator whine or power steering pump whine. It sounds exactly like a timing belt that is too tight.

I've heard this on other cars with a tight timing belt that uses manual adjusters, however on these J35s the timing belt tensioner is not adjustable and it isn't an indexed adjuster like on some cars (indexed as in it extends into ratcheted positions so it can't be pushed back in). I can't think of any way to adjust the tension.

I considered the fact that it could be a faulty pulley bearing or faulty water pump, however it doesn't have the distinct chirping or chattering sound that I typically hear with bad bearings. That is also not very likely with the Aisin kits as far as I can tell. It really sounds like a whining/whirring sound from a belt that's too tight. I pulled the timing covers and inspected the newly installed belt and it looks fine with no abnormal wear and it isn't excessively shiny.

Is it possible that the new Aisin tensioner in the kit is faulty and putting too much pressure on the belt? I have a spare tensioner that I installed around 90K miles (so only 15K miles on it) that was working fine; I removed that when changing the timing belt and installed the new one from the Aisin timing kit. I'm thinking of putting the old tensioner back on to see if that changes anything. Or is it possible that the Mitsuboshi timing belt included in the Aisin kit is just noisier than the OEM Gates/Unitta belt?

I've driven a few thousand miles since making the change and there are no problems, in fact the car runs and drives stronger than ever especially after new plugs and VCM disabled.
 

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Could it be some sort of electronic feedback through the speakers? Do you have any aftermarket speakers, amp, etc? Sorry but your initial description reminded me of my old stereo modding days. Not that a timing belt service has anything to do with stereos.

Since you can hear this sound in the cabin, but not outside the car or even with your head in the engine bay, perhaps it is a vibration that is coming through as sound in the cabin.
 

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Sounds like a bearing somewhere IMO.
 

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Or is it possible that the Mitsuboshi timing belt included in the Aisin kit is just noisier than the OEM Gates/Unitta belt?
I've done this job a few times for family members, always used the Aisin kit with the Mitsuboshi belt. I have never noticed the noise that you describe. I suppose that it is possible you have a noisy belt, but I am under the impression that Mitsuboshi is a very good, OEM quality belt. Examine the edges of your new belt for wear or fraying. Any chance that one of the dished washers in the crankshaft gear area got turned around and is rubbing?
 

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Interesting, I just realized I have the exact same symptoms. I am not sure why I didn't connect on it the first time I read your post.

We also have a "whirring" noise that is most detectable inside the cabin. I can hear it when I get on the passenger side of the engine, but the normal engine noises mask it.

I also did the Aisin kit, DIY, at 104k.

At 106k, we started noticing some "shudder" in the power steering, which was noticeable when cold, in the morning, when turning the wheel at a low idle while in gear. I swapped out the fluid, o-rings, and pump reservoir since those are cheap and possible suspects. No change on the shudder. Strangely, this seems to have improved somewhat over time, or maybe we aren't as sensitive to it. I chalked it up to the new Bando belt, and the fact I re-used the old drive belt tensioner (which was showing signs of leaking on the hydraulic) just slipping a little during heavy power steering use, or maybe gonna need a new PS pump at some point.

Around 110k, I noticed the whirring noise. ONLY on cold starts in the morning, and ONLY at low idle, and mostly detectable when in gear, D or R. If you let it idle for a few minutes, it doesn't happen anymore.

I had planned on popping off the drive belt on a cold morning to remove that from the equation.... figuring it was the drive belt tensioner.

Now you got me nervous.
 

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Are you guys sure this is not transmission noise? The pump gears in the transmission typically make a bit of a whine, not anything to worry about.
 

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I would replace the Serpentine belt bearing, Could be with new parts this bearing has more pressure and the easiest one to replace. It that didn't help i would bet on bad timing belt bearing.
 

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With the car at idle, does the sound increase when you turn the steering wheel?

I have a fairly noisy PS system and have been living with a constant whine for years. I had it prior to doing my timing belt though. I did the same exact service as boom described above. No change in the sound. Mine noise is definitely PS related as I can hear the sound increase and decrease relative to turning the wheels. My rack leaks at the passenger side inner tie rod. I am thinking that is letting air into the system.
 

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With the car at idle, does the sound increase when you turn the steering wheel?
Mine does not, no impact. And if you remove the drive belt as the OP did - and there is no change, that rules out anything power steering related.
 

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Discussion Starter #11
Interesting, I just realized I have the exact same symptoms. I am not sure why I didn't connect on it the first time I read your post.

We also have a "whirring" noise that is most detectable inside the cabin. I can hear it when I get on the passenger side of the engine, but the normal engine noises mask it.

I also did the Aisin kit, DIY, at 104k.

At 106k, we started noticing some "shudder" in the power steering, which was noticeable when cold, in the morning, when turning the wheel at a low idle while in gear. I swapped out the fluid, o-rings, and pump reservoir since those are cheap and possible suspects. No change on the shudder. Strangely, this seems to have improved somewhat over time, or maybe we aren't as sensitive to it. I chalked it up to the new Bando belt, and the fact I re-used the old drive belt tensioner (which was showing signs of leaking on the hydraulic) just slipping a little during heavy power steering use, or maybe gonna need a new PS pump at some point.

Around 110k, I noticed the whirring noise. ONLY on cold starts in the morning, and ONLY at low idle, and mostly detectable when in gear, D or R. If you let it idle for a few minutes, it doesn't happen anymore.

I had planned on popping off the drive belt on a cold morning to remove that from the equation.... figuring it was the drive belt tensioner.

Now you got me nervous.
This sounds exactly like my car.

It's NOT the serpentine belt. I can still hear the sound with the serpentine belt removed. I also have a brand new serpentine belt tensioner that I installed shortly after doing the timing belt replacement. Like I mentioned (and user 'boom' said above) it's only on cold starts in the morning and only at low idle when in gear. After the engine is warmed up I can't hear it.

I pulled the timing belt covers and inspected the belt edges, they're perfectly fine. Belt is tracking fine on the camshaft sprockets. When looking under the hood, I can barely notice this sound and can't even isolate it to the timing belt area. This got me thinking about the transmission.
Are you guys sure this is not transmission noise? The pump gears in the transmission typically make a bit of a whine, not anything to worry about.
I'm not sure if this is transmission noise; never had a Honda or any transmission whine only at low idle, but I'm not ruling it out. Is it common or even possible? I'm at 105K-ish miles now, and I have probably done three drain and fills with Valvoline MaxLife transmission fluid. Just recently I started noticing my downshifts are a bit more harsh than I remember. I plan to do another drain and fill at the next oil change with Honda DW-1.

I'm also wondering if this is PCV valve or idle air control valve noise, since it's only at low idle. Idle is sometimes a bit 'rough' on cold starts. Not lumpy like bad coils/plugs, but not buttery smooth like when it was new. I'm going to remove and inspect the PCV valve and maybe clean the IACV to see what happens.

It's also possible that this sound was present before I did the timing belt job, and I only noticed it now after the timing belt job because I'm listening carefully for any anomaly.
 

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Only when cold and goes away after a couple minutes?

On a higher mileage vehicle that falls under the category of wait for it to get worse. Old cars make noises sometimes, even more so when it's very cold. I take it easy on them while they are warming up and as long as the noises go away I don't worry about it.
 
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