Hello everyone, I’ve been trying to hunt down this rattling noise I get at the beginning of a rev on my 2002 Honda s2000 for a little bit now so far I have replaced the timing chain tensioner and exhaust manifold gasket although my car does seem to be running a little bit better the noise is still there. I have no misfires I’m not losing oil and I’m not missing coolant. At this point, I’m starting to think it’s one of the pulleys possibly. Let me know what you think!

 

Try taking off the serpentine belt and see if the idle sounds different. Also, with the engine off, you can spin each idler to narrow down the noisy one.

Good luck!

 

Doesn't get any easier this to check for pulley bearing noise.

-- Chuck

 

takes like no time to take the belt off

 

Just keep randomly replacing parts. That is always the best strategy.

 

Update:I took the belt off the car and started it and the noise was gone, then I noticed the idler would spin basically forever so I replaced the bearing in that and the tensioner with the recommended 6203 2RS, put everything back together and started the car again and the noise was back, my mechanic’s stethoscope came in this morning so I used it to probe around while the car was running, I checked the valve cover, timing chain cover, water pump housing, and AC clutch and they were all pretty quiet, but when I got to the alternator housing the rattling was the loudest there, I even pulled one side of the stethoscope off my ear and the rhythm lined up perfectly, what’s confusing me is that when I take the belt off and spin the alternator by hand it feels completely normal, I also tried unplugging the green power wire from the alternator and starting the car but the noise was still there.

 

The belt puts a sideways load on the alternator pulley bearing. The alternator bearings seem to be replaceable. Perhaps borrow an alternator for the afternoon before guessing and replacing the whole alternator and then finding out something else is wrong?

-- Chuck

 

with this car being 24 years old now I think replacing the alternator completely would be kind of a good thing? I found somebody who has a Denso for the AP one on Facebook marketplace for 100 bucks I might just snag that and swap the whole unit. I’m just tripping and can’t stop thinking about what else it could be if it still made that noise after swapping the alternator even though the loudest thing is the alternator based on the Mechanic stethoscope.

 

eBay is awash with S2000 alternators under $100. Can you read the data plate on what you have? I'm not sure if model year of the car matters.

-- Chuck

 

i’m pretty sure the alternators are all the same for this car I will try and get the info of the data plate later today when I get off work. The car is at a friend‘s custom shop, where he’s kindly letting me do all this work on it myself. I might just order one to have to swap if I have to remove it to read the data plate.