Just helped mother dearest buy a new car (3rd gen max of course :P) which is a damn sight better then what she was driving before, but theres this one problem that sh'ts us both to no end.. i'll try and explain it as best i can.

Its a whirring kind of noise which fades in and out at a particular RPM range (between 1,600 and 1,900rpms) - unfortunately thats the range mum uses 95% of the time.. when the whirring noise kicks in you can really feel it through the steering wheel and more so the floor of the car.. (even in the back seat) ,... at first i blamed wheel bearings but we've found out they are perfectly fine... besides, its only occuring between this given rpm range, below and above it? whirring / grating is gone....

I've had a dude tell me engine mounts, but if that were the case, wouldnt the car be vibrating quite severely when stationary, and in drive? because it doesnt, its very solid and vibration free.

Apparently all cars have a "vibration point" in them.. but for some reason, on this one its far more pronounced at this rpm range... its horrible and it really spoils the smoothness of this car...

I'll also note that once you're at 42/45mph and no longer under acceleration, the grating/whirring isnt really noticable anymore, even though the rpms are within the offending range...

ie. this whirring is only very noticable when the engine is under load within the offending rpm range...

If i sit in park and rev the car around the 1,600 to 1,900rpm range, once again the whirring/grating isnt felt.. i presume because it only occurs under load.

I hope thats detailed a decent enough picture for ya'll ... would love to get some feedback on what this might be.....

Oh, i've also had a mech tell me its not engine mounts for the same reason i mentioned above, the car is solid when stationary and in gear.. he said it seems like its caused by an accessory to the engine.. he then went on to say check how secure the air intake is... unclip it and re-attach it to be sure everything's solid blah blah... could he at all be on the right track? i wish i was more mechanically minded

Thanks a crapload for any support on this folks!


Edit: its not gearbox related either...... you'll be accelerating in a given gear where the grating noise is apparent then you see the tacho go past the 1,900rpm mark and the grating dissapears... but when the auto switches to the next gear (doesnt matter which one) the grating noise INSTANTLY comes back.. why? because the motor's back within the offending rpm range of 1,600 to 1,900!

 

Just a guess but check your power steering fluid level maybe? I have a bad leak in my car and it makes a whirring/supercharger sound when it gets low, but then again it would do it all the time not just when your driving. Also how's your allignment? Does it steer straight? I've had cars where the tires were barely off balance and they'll make noise and ride rough only at a certain speed.

 

All the fluids are spot on, the car's also just had a major service (of which didnt get rid of the noise/grating feeling at all) ... plus speed isnt relevant to this.. its when the car's under load/acceleration within a specific RPM range.

 

I got a question... why did you buy the car if it makes this noise?

But it might be a intake leak that makes the whirring sound but im not sure other than that i would need to be in the car to hear/feel it

Good luck on fixing it though

 

Because annoyingly enough, the noise/feeling wasnt prominent when we testdrove it :S

Between when we testdrove it, and picked it up 4 days later, the guy took it to a mechanic to get it roadworthy as it is required to provide a slip of roadworthiness to the traffic authority in order to switch the rego into your name (at least in australia, not sure how it works for you guys in the U.S.).

I know he had changed one of the rear tyres (it didnt pass) and some other basic non-relative stuff.. but yeah, i think it was just coincidence that it became more pronounced after we bought it :S

Apart from this annoying problem the car drives beautifully in every respect and has amazing gobs of power when you plant your foot and let it drop a couple of gears.. she seems to have more pull than my baby

 

Maybe an alignment or wheel balance.

 

FOUND THE PROBLEM!

with the assistance of a reputable mechanic nearby who's been in the biz for 43 years, we've hit the jackpot folks.

Idler pulley (small one at the top of engine, not the lower one - this is a VG motor btw), i believe this is for the air compressor or some such?? anyhow, he demonstrated the severity of it by putting a big screwdriver up to it with the engine running idle, and getting me to place my ear on top of the screwdriver handle... the chaffing noise was shocking.. (even at idle) but got terribly worse when he revved it up (naturally)

so relieved we've finally gotten to the bottom of it... shot bearings/pulley assembly

Only thing i still dont understand though, why is it only felt and heard inside the car within a given RPM range under load? thats the most severe point of vibration in the rev range or something? i meant to ask him this....

 

centrifical force

 

When anything's turning and it's off balance or distorted it'll usually have a peak in noticablility (is that a word??)

 

How much did you pay for the pulley?

 

Well $60 AUD later and it didnt fix it

Had the bearing replaced inside the pulley, not the actual pulley as thats obviously fine... saves money that way for the same end result... pity it isnt the cause.

After 3 weeks of solid focus on this issue, i hereby declare to have given up.... I (and evidently several mechanics) have *NO* idea what it is... I just find it very odd that this grinding/whiring only occurs between the window of 1,600 to 1,900rpm under even the slightest acceleration... what the ****? cant ever say i've heard/seen a car do that before..

meh >

 

obviously it isn't obvious.

You are ASSuming that it is fine.

anyhow, this is one of those problems that are hard to diagnose over the internet.

 

congratulations! enjoy the beauty of Maxima-izing.

Quick summary for skimmers: whirring was experienced at a specific range of RPM... resolved with replacement of idler pulley.

 

bah, i was told by someone here that it was the idler pulley as well. i have the same symptoms and i am almost positive now that it's the water pump. after removing all accessory belts and it still occurred. high pitched vibrating tone that you can feel through the shifter and the inside of the car? humming sound? like a tuning fork? listen around the pump and see if that's the area it's coming from. that's where it's coming from on my car.

 

Sadly enough, its not the water pump, as the symptoms were occuring before AND after having a brand new water pump and timing belt fitted a couple weeks ago