Name that noise?

[kwhitmer83]

2005 Altima 2.5 S....Im hearing a grinding type noise only when i shut the car off. Its coming some where in the engine bay, and slows with the same rep as the engine. I thought it might be the tensioner pulley but after changing it out with a new one, it did not help. Any suggestion?

I have a video of it but i cant get it to load on here....

[VStar650CL]

Without diving into the engine box, if the noise is in the AC compressor or clutch then it should change or stop depending if the compressor is pumping or cycling when you kill it. Same for the power steering, try turning it to one lock for maximum pressure and see if there's a change when you kill it. The alternator and water pump will require a stethoscope with a needle-end plus an assistant to work the key. If it wasn't the tensioner, my next guess would be the alternator. I've seen them make some awfully weird noises under sometimes-odd circumstances.

[kwhitmer83]

https://www.flickr.com/photos/191144855 ... res/1640qF

hopefully this works......

[VStar650CL]

Nope, but if it's a YouTube etc, just post the link.

[mdmellott]

https://www.flickr.com/photos/191144855 ... res/1640qF

hopefully this works......

What is turned by the engine but doesn't necessarily stop turning when the engine stops turning? "Name that noise." I'm not a game show fan but your video clip is telling. I can see the engine stops turning but the awful sound of something still turning is clear. My first guess was cooling fan clutch but then I found your Altima doesn't have one. That leaves the A/C clutch as my best guess.

[VStar650CL]

That would be my guess also. On a Sunday I don't have ASIST in front of me to check, but I'm pretty sure an '05 is too old to have a clutched alternator. What I said earlier should apply, if you have someone shut it off while you can see the compressor is engaged, the noise should disappear or change in some way. Juice to the clutch gets cut as soon as the key is turned off, but mechanical inertia should still cause an audible difference.

[kwhitmer83]

I removed the belt and spun each pulley by hand. I heard nothing when doing this. Also I started the car without the belt on and when I shut it off the noise was not there. It has to be one of the pulleys. Going to be a headache figuring out which one.

[mdmellott]

... too old to have a clutched alternator.

I never knew an OAP was a thing. I'm still too old school myself but forever learning. Thank you for that. Reading up on overrunning alternator pulleys, as I am now intrigued with the idea, I see the advantages of this simple mechanism. Of particular interest to me is whether or not I can find a suitable retrofit to go onto my '02 Pathfinder. Any increase in fuel efficiency performance would be a welcomed improvement. I've already done all I can to increase my ride by an additional 3mpg over its stock configuration. That's a huge percentage increase given that 18mpg was supposed to be the average mpg for my model on the highway. Getting even one more mpg, if possible, with an OAP retrofit would be great, and something fun to play with. Any ideas?

[VStar650CL]

As I recall, almost all the Nissan alternators from '13 up are clutchers, and the ones with "smartwork" will all do self-regulation if you simply leave the control pin open. So if any of them will fit the holes on your Path, there shouldn't be any problem employing it.