Hello, I purchased a 2001 Honda Civic EX today to use as a cheap daily commuter. Unfortunately, it makes an atrocious sound as demonstrated here:

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In 1st gear, if you're under ~2500 RPMs, everything is fine but once you go over, there is a very loud rattling sound that is RPM dependent.

From then on, it occurs in every gear, even if you stay under 2500 RPMs. It isn't as audible in 5th but it's hard to tell since there's road noise at that point.

After you come to a stop, put the car into neutral, and then into first gear, the noise will stop until you get to ~2500 RPMs. Rinse and repeat.

I should also mention that I can hear faint rattling at idle that goes away when I push in the clutch, which makes me suspicious of the ISB.

The transmission does not grind between shifts and the clutch does not slip.

Do you guys think that it's the ISB or am I looking at a new transmission?

Thanks in advance!

 

A bad input shaft bearing should only make noise when the engine and input shaft are rotating at different speeds. Which would be when you are changing gears, or basically any time you have the clutch pedal pressed and the engine is running.
It doesn't sound like that is your problem.

If this sound starts happening, and you turn the car off, then back on soon after, does it resume making the noise? Or do you have to drive past 2500 RPM again?
Is your check engine light on?

 

From everything I have read and been told, noise when you let out the clutch that goes away when you press the clutch pedal, is input shaft bearing. This is the same problem I have but am in the process of deciding whether to replace or rebuild the tranny.

Mine is very loud even at idle, and gets worse when driving until road and engine noise drowns it out. Makes the car sound like **** tho.

 

My mistake. I was thinking a pilot bearing for the input shaft. Something that would be located in the flywheel or crankshaft on some cars.
This could definitely be bearings in the transmission that are going bad. I've had this happen to the factory transmission in my 01 hx.
The way I determined the transmission was going bad was to drive the car at low speed in 1st gear. Bring it up to 3-4k RPM and maintain speed. Then press the clutch pedal in, while leaving it in gear and letting the engine drop back down to idle as you roll. If you keep hearing the vibration sounds, leave your foot on the clutch and put the car in neutral. If the noise reduces or goes away, it's certainly something with the transmission.
You can do any combination of low speed roll (so the road noise is quiet enough to hear vibrations), and putting it in and out of gear. Maybe try getting up to 20 mph in 2nd gear, then shift down to 1st gear with your foot on the clutch, just to spin the input shaft up to a higher speed (no need to release the clutch).
When in gear and the car is rolling, it causes the transmission to rotate - and if it's got bad bearings you should hear some bad rattling/vibrating sounds.

 

Thanks for the reply. Do you mind listening to this and seeing if it could still be the input shaft bearing? It almost sounds like something is vibrating/rattling and not grinding.

http://vocaroo.com/i/s0vURHFRVBIK

 

Hmm, thanks for the advice. I will try putting the car in gear while it's rolling and see if it makes the noise still. I recorded some more audio while driving around the block today.

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Also, what's weird is that if I give it some gas leaving in first (not launching but just giving it medium gas), the noise does not occur until I switch into second. With that being said, I can get to 4000 RPMs (haven't tried higher), noise free. Sometimes though, the noise will start as low as 1500 RPMs depending on what I'm doing with the throttle.

 

So I have the car jacked up and tried to have my dad listen for the noise while the tires were spinning. However, the noise is not there. I'm guessing this has something to do with no load being on the drivetrain. However, wouldn't the transmission still be spinning as usual?

 

It's hard to say. I listened to the recording and it sounds about right. But like I said, mine was making a lot of noise even just sitting and idling, so no load on the drive train.