Josuavemente

just bought a decent 350z for a decent price(i think). Maybe not the smartest move but it is my first manual car and so a lot of the noises that come with this car are unfamiliar to me.
Anyway, I've noticed that when i rev the car to around 2.5k - 3k rpms there is a grinding/scraping noise that comes from the front of the car. I've tried this while parked in neutral, and while in gear (which i can hear when i let the engine slow down the car). I should also mention that if i press the clutch in while the car engine brakes, the sound goes away.
I'm not really sure what the sound is, but the sound is loud enough to make me think there is a problem with the tranny or something. Any help would be greatly appreciated tho, I'd be sad if my car fell apart so quickly after buying it.

Heel Til I Die

iTrader: (2)

These transmissions are noisier than the average manual. My guess - it's either normal transmission noise or the throw out bearing.

dkmura

iTrader: (64)

The key here is the grinding sound goes away when you depress the clutch. Most likely a worn throwout bearing that's easily checked by a good technician. How many miles are on this Z?

Josuavemente

it's at 150k miles on the odometer. I might as well have a technician look at it, you're right. Although, could this be something I could check myself with a bit of work? And would driving with a worn throw out bearing potentially cause more harm to my transmission? Thank you both for the help btw

Spike100

I agree with the others here. It is likely the throw-out bearing making the noise. At 150K miles you probably need a new clutch and any worn associated parts.I have 125K and my throw-out bearing is making the same noise you describe. I have setup an appointment with my repair shop to replace the clutch and related components that are worn. I also plan taking advantage of the disassembly when the clutch is replaced to also replace the frontend cross member (mine is rusted ), front suspension bushings, and the rear differential bushing.

dkmura

iTrader: (64)

You'd have to pull the tranny itself to do a full inspection and even then, you'd have to know what you're looking at. Your time would be better spent picking a decent shop or technician to do the diagnosis and possibly repair. A worn throw out bearing won't damage the tranny itself, but won't do the flywheel any good, so get ready to replace the clutch disc, pressure plate, throw out bearing and related parts all at once. The dual mass flywheel can be damaged by excess wear and isn't easily turned, so keeping it in good shape should be your priority.

Heel Til I Die

iTrader: (2)

^^^ +1

If you're going through the trouble and time of dropping the tranny to inspect the TO bearing, I would go ahead and replace the components that DK mentioned while you have everything out.

MicVelo

What year is the car? Helps to know if we're dealing with a throwout bearing or a CSC (concentric slave cylinder.)

Also, you mentioned you rev'd the engine in neutral.... what was the result? Noise still there? Was clutch in or out? Did the noise change pitch at all? All these questions and more are to try to narrow the diagnosis to what areas to look at.

As mentioned, a cocked or worn T/O bearing by itself won't necessarily hurt the trans; BUT grinding/thrashing is NEVER good and could lead to ancillary damage as mentioned, say, to the transmission input shaft, the clutch or, worst case, if the T/O bearing assembly (bearing, pivot, clutch arm or CSC) isn't doing its job completely to fully disengage and causing any gear grinding, in that case, yes, it could damage the transmission.

But y'know, even though the sound goes away at clutch disengage, don't rule out engine related noises. Depressing the clutch pedal unloads the engine, which could also be making noises under load... pulleys, dampers, etc. Have the tech look at everything. Tell them symptoms, do not tell them your speculation of what it might be. Not a diss on your tech but many will take said diagnosis and concentrate there without looking at everything. I used to have to tell lazy techs in the shop to NOT take shortcuts.... do the analysis THEN arrive at a fix solution.

Don't mean to be Gloomy Gus here but always best to err on the side of a complete analysis and solution rather than throwing parts at it.

And, failure on the road is never good anyhow.

Spike100

Hi Mic. This one is pretty easily diagnosed if I have the correct information and understand the facts:

• A car with 150k miles has original clutch assembly.
• A significant noise occurs when the clutch is engaged.
• The noise goes away when the clutch is depressed.

I don’t disagree when you say…
…but this one seems obvious.

We have fun diagnosing problems on a Forum, but obviously your cautions when doing this are very legitimate.
--Spike