Hey guys,
We were on the hunt for an AT 2nd gen fit for my girlfriend and found a clean one owner example with 169k miles and plenty of maintenance records. The car had a noticeable whine which sounded like it needed a belt & tensioner (the old ones were pretty worn). Turns out that wasn't the issue, I replaced both with new OEM equivalent parts. When accelerating, the car sounds like it has straight cut gears almost. The sound seems like it's coming from the transmission side only when the gearbox is engaged (cannot replicate the sound at idle or in neutral). It's consistent with engine rpms. When coasting the noise goes away about two seconds after letting off of the throttle which makes me think it could be an internal bearing in the transmission that only whines under load. I checked the trans fluid and it was at the proper level, last transmission fluid change was about 25k miles ago so that's my next step. The car shifts perfectly fine. Anyone have any experience with this? Thanks!

 

Without a better description or video of the noise it is hard to say what it is. A drain and fill of the transmission can't hurt, getting a look at the portion of the fluid coming out when doing that might tell you more about the condition of the transmission. Could be wrong fluid in the transmission, the Honda automatics are very picky when it comes to fluid. IF you changed the tensioner, did you check the other pulleys? The bearings might be worn and making noise at higher rpms, or the AC Compressor. Try the old mechanics trick of grabbing a long screwdriver, putting the handle to your ear and carefully, very carefully poking into thigns you think might be making noise.

 

This^^^^. Also check the alternator with the screw driver trick. Might have a bearing going out.

 

Given that the whine only occurs when the gearbox is engaged and is consistent with engine RPMs, it does point towards something in the transmission. Since you’ve already replaced the belt and tensioner, checking the transmission fluid is a good next step. If it’s low or dirty, a fluid change might help. If the fluid looks good, it could be an internal bearing or even something related to the torque converter. Since the car shifts fine, it’s less likely to be a major issue, but keep an eye on it. If the noise persists after the fluid change, you might want to consult a transmission https://tropical-casino.com/ specialist for a deeper look.