Trying to figure out this pulsating rubbing/humming sound in my Civic Si/SiR

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2 months 2 weeks ago - 2 months 2 weeks ago #201350 by 02EP3
'02 Honda Civic SiR (Canadian model, it was called the Si in the US).

Recording of noise , revving while parked (you probably won't hear it without speakers or headphones)

It's best heard from the inside the car, and clearly coming from the front-right. I can hear it from the pulley area with the hood open, but I don't have adequate recording equipment to capture the audio.

The pulses increase/decrease frequency proportional to revs, not road speed. Nothing else makes any difference to the frequency or volume of the noise: fan, A/C, engine hot or cold, at idle or driving, clutch in or out, in or out of gear. All accessory equipment is operating normally (A/C, alternator and water pump. P/S is electric on this car.) and the engine runs and idles no problem.

I have already replaced the idler pulley, tensioner pulley and serpentine belt. The tensioner spring action was smooth and quiet when pulled back manually.

What else could it be?
Last edit: 2 months 2 weeks ago by 02EP3.

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2 months 1 week ago #201351 by jimchndlr
When was your timing belt last changed? Maybe feel the upper cover with your hand for any vibration, but it's tough to check the lower cover that way.

Also, you might consider investing in an automotive stethoscope, it really helps localize engine noises.

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2 months 1 week ago #201352 by relative4
Automotive stethoscopes retail for about $5, so... yeah.

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2 months 1 week ago #201354 by 02EP3
Thanks, I've actually used a stethoscope on bolts that secure the idler and tensioner pulleys. It actually seems loudest on the tensioner pulley, but that was already replaced recently (??). None of the other pulleys (alternator, water pump, A/C, crank) are free-spinning, so I can't just put the stethoscope on those.

Also, this engine has a timing chain, not a belt.

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2 months 1 week ago #201357 by relative4
By "free spinning", do you mean you removed the belt and spun them by hand?
Listen with the engine running. Touch the stethoscope to the alternator, PS pump, tensioner, etc.
If the tensioner was recently replaced with a Chinese unit, that could be the problem.

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2 months 1 week ago - 2 months 1 week ago #201359 by 02EP3

By "free spinning", do you mean you removed the belt and spun them by hand?

I did do that, yes. But what I meant is that they're the only pulleys that aren't driving an accessory.

Listen with the engine running. Touch the stethoscope to the alternator, PS pump, tensioner, etc.

Oh, yes, I did do that with the alternator (not the pulley), it sounds... alternator-y? Normal, I think. Just a light swishy sound that I can only hear with the stethoscope.

If the tensioner was recently replaced with a Chinese unit, that could be the problem.

It's a Gates unit. Made in Canada... or possibly just "assembled" in Canada with the bearings sourced from China, depending on what you read. I'm starting to think that may be the case. The Honda OEM idler pulley was clearly better constructed than the aftermarket unit it replaced (also a Gates).
Last edit: 2 months 1 week ago by 02EP3.

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2 months 1 week ago - 2 months 1 week ago #201362 by relative4
Gates tensioners are notorious Chinese crap.
Not sure about Honda, but for Subaru the good ones are made by Aisin.
Last edit: 2 months 1 week ago by relative4.

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2 months 1 week ago #201420 by 02EP3
So, does anyone know the right procedure for replacing the tensioner pulley in this car? Can it be done without removing the whole tensioner assembly and bunch of other things?

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2 months 1 week ago #201421 by relative4
Are you just replacing the pulley? You should replace the whole tensioner. The damping wears out, allowing the tensioner to oscillate. This leads to premature belt and pulley wear and of course noise.

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2 months 1 week ago #201424 by 02EP3

relative4 wrote: Are you just replacing the pulley? You should replace the whole tensioner. The damping wears out, allowing the tensioner to oscillate. This leads to premature belt and pulley wear and of course noise.

I'm not sure the tensioner itself is bad, though, and I'd rather not replace the whole expensive part if I don't have to. When I replaced the idler pulley, the tensioner action was smooth and quiet.

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