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

[AB]

’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?

Topic

[Jim Chandler]

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.

[Billy]

Automotive stethoscopes retail for about $5, so… yeah.

[AB]

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.

[Billy]

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.

[AB]

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).

[Billy]

Gates tensioners are notorious Chinese crap.
Not sure about Honda, but for Subaru the good ones are made by Aisin.

[AB]

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?

[Billy]

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.

[AB]

[quote=”relative4″ post=201421]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.[/quote]
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.

[AB]

So, I just checked and I notice that the tensioner pulley can be jiggled by hand, with the belt on. I wonder if the shop under-torqued the pulley bolt (I’ve had to “clean up” after them before).

Before I go spending money on parts, I’d like to try and torque it to spec. Two problems with that:

1. The space is too tight to fit a torque wrench. I might be able to get in from underneath, or use the extension on my belt tool (although that will change the torque dialed in and I don’t know the math on that). EDIT: I may be able to just figure this out using the idler pulley bolt to check the torque setting with the extension and compare, since they’re both 41 ft/lb.

2. How can I torque it down when the bolt torque (41 ft/lb) exceeds the spring torque (27 ft/lb)? I don’t see anywhere to lock the tensioner. I guess I could just let the tensioner move to the end of its range, and then torque down the bolt, but I don’t want to wreck it.

[Billy]

Pics might help.

[AB]

[quote=”relative4″ post=201463]Pics might help.[/quote]
I’ll try to get some tomorrow. Cold as balls out there today 😛

[hondaguy453]

The pulley on the tensioner wiggles around? Usually the pulley itself doesn’t get removed from the tensioner. Also, there should be marks on the tensioner body which tells you if the tensioner spring has lost its ability to retract. Usually three marks on the one side of the body and one on the other side. The one mark should line up perfectly with the middle mark on the other side. The other two marks are thresholds for the tensioner spring. If the mark is outside of those, then the spring is faulty and the tensioner should be replaced.

As for torquing the pulley, be careful. I can’t remember if there is an access hole to lock the tensioner, so if you’re going to torque the pulley bolt without it, be careful.

You’re sure the noise isn’t coming from inside the timing cover? There is a black cover near the rear of the crank pulley. This is where the timing chain tensioner is and could be what is causing the noise. Remove that cover, if that is in fact where the noise is coming from, and check to see how far out the plunger is. It shouldn’t be too far out. Also, with the cover removed, you can spin the engine by hand to see if the plunger moves. You should also check the timing chain guide for wear, as this is why the plunger is all the way out.

[AB]

Thanks for all the helpful info, hondaguy.

The pulley for this tensioner is replaceable on its own. I have a PDF of the service manual for this car, which confirms that, but doesn’t give any advice on torquing it down other than the torque spec.

The tensioner body itself doesn’t move out of spec. However, it does bounce around slightly (maybe 1mm) at warm idle.

The noise definitely sounds rotational and I’m quite certain it’s originating from a pulley. I’m going to try and get my stethoscope on all the pulleys and on the timing cover this afternoon.

[AB]

Alright, I did all the troubleshooting that I could think of:

• Slipped off the belt, spun tensioner pulley by hand. It’s a tight fit getting my hand in there and I can’t really spin it fast enough to hear anything. But, the side of the pulley facing the engine appears to have some imperfections (ie.: it’s not perfectly smooth).
  [li]Timing cover sounds like normal, quiet metallic sounds
• Put the stethoscope on every pulley and accessory I could with the engine running. I’m not sure if I got the water pump, because it’s buried deep in there and I can’t really get at it without a hoist.

[li]Put the stethoscope on the idler pulley bolt, tensioner pulley bolt and the tensioner unit while revving the engine by hand. It’s clearly loudest on the tensioner pulley bolt.

Edit: pic of alignment markings while engine is off.

[Author]

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