Ok guys, so ive posted in a couple of threads regarding t-case whine. My evo’s whine (or loud hum) is most apparent when in gear and accelerating. When the gas is let go of, clutch is pushed in, or car is put in neutral, the sound recedes but there’s definitely still a hum in the background. This has been going on since I bought the car in august. Only now have I been paying close attention to the sound and lately I’ve been noticing when the sound ISN'T there and the car sounds SO much better and even feels better to drive. I have a new-found love for my exhaust now that I can notice when the humming is gone and I want it to stay like that ALL the time!

Anyway, the reason I now suspect it is NOT drive-train related is because today at a stop light I steadily revved the engine to 3.5k rpm and the loud hum was definitely there! The pitch rose with the increasing rpm exactly like I experience when driving. I did this in neutral with the clutch engaged AND disengaged. I also did this later on at another stop light when I noticed the whine had gone away during driving...no loud hum that time, only a nice throaty exhaust sound.


Now this means that the drivetrain is not causing the sound right??? So is it something engine related? The sound comes and goes does not seem to be temperature related (outside or engine temp.) Can anybody offer some theories on what it could be? Has anyone else ever had a loud whine or hum that sounded like a bad t-case or a bad wheel bearing and it turned out being something completely different? I’d appreciate any help. Thanks!

 

Maybe a vaccume line has a crack in it or something.

 

I dunno i doubt a cracked vacuum line can produce that loud of a hum. thanks for the suggestion though, i'm definitely gonna check the engine bay for anything suspicious. Any other ideas???

 

2nd on vacuum leak. Youll be impressed how much pressure runs through those lines. A slight crack/hole can make a very loud noise.

 

Maybe its coming from your girlfriend? Sorry I had to. lol. +1 on checking all your lines. Good luck!

 

ahahaha good one about the gf. but yeah thanks guys. i'll definitely look into checking all my hoses and vaccuum lines when i get the chance. i'll update if i find anything.

 

ok so I went out to my car during lunch to check the engine bay. I had a friend rev it so i could listen for the whine. Its definitely not a hose. its coming from the engine near the timing belt cover. The whine gets louder and higher pitched the higher the car gets revved. Sounds like a loud RC car.

Can the belt be making this noise? Or is it cam gears or what do you guys think it could be? Again, some times its very loud and others I can barely hear the whine if at all so i'm not sure what would cause it to be intermittent. Appreciate any input you guys can give. Thanks

 

Sounds like your timing belt is maybe put on too tight. loosen up the tensioner to give it some slack and tighten the bolt back up .

 

Take serp belt off see if it still makes the noise

 

ill be the one to give u some different advice? whens the last time you changed your power steering fluid? could possibly be the pump going bad. IF its been at least 30k + since your last power steering flush, have the fluid changed see if the noise is eliminated or reduced. If it is hopefully your power steering pump isnt going bad?

 

I just did my 60k and my car is doing the same. Did you do any of the things posted. I need this noise gone too.

 

Did it start making a noise after the 60k or was it doing it before too? And no i havent done anything to the car yet. Unfortunately i dont have a covered garage so its a b**** to work on the car in the cold.

Yeah I've had a power steering pump go bad on my 300zx and it did make a similar sound but only when turning the steering wheel at slow speeds. It never made a sound while driving in a straight line. And keep in mind the sound gets louder relative to the rpms, so if im driving in straight line I shouldnt be putting more load on the ps pump? and usually bad ps pump sounds are LESS noticable the faster youre driving right? anyone correct me if im wrong

At this point I think im gonna schedule a visit to AMS to get my drivetrain fluids flushed and also get this issue checked out. Maybe it is a belt issue as others have said. But more ideas are always welcome so keep them coming!

 

+1 I had my ac compressor pulley crap the bed..

 

well being the ps pump is driven by the serpentine belt, the fluid gets pushed through the system reguardless, but if you hear it at low speeds when turning it is a possibility, ps flushes arent even that expensive, and a good thing to use to rule out other possibilities. So it could be that pump, or like ^^ said could be your ac compressor pulley, turn your a/c on while driving see if it becomes more pronounced. IMO take it to a shop save your self the headache and only thing that might hurt would be your wallet haha jk, good luck man.

 

^^ +1 , specially something like that would scare me.