As of yesterday, my car has developed a whine/whistle from underneath the hood. It corresponded with the temperature dropping a good bit. It also gets higher with RPMs. I wonder if it is something I should be immediately concerned with, such as a timing belt pulley or something else. My timing belt is due for a change in 13K miles.

I have a 95 960 with the same whine. My timing belt and tensioner are new, and the serpentine belt is new. The whine is when the car is driving, and is not there when at idle, which I believe means it is not related to the timing belt or serpentine assembly. I am guessing it is the transmission, but my trans and fluid are clean. Do these symptoms match yours?

I also get the whine when I rev the engine while in park or neutral, so I don't think it's related to the drive train.

Does it happen when car is stopped?
The source of the whine can be determined with a 3/8" to 1/2" plastic hose held to your ear and probed around the front of the engine, use care doing this. It can be alternator, power steering, timing belt tensioner or idler bearings and more. Removing the serpenteen belt as test sounds like a good idea.

Good practice to change timing belt tensioner and idler with every other belt change. You do not want any type of timing belt failure.
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David Hunter

Dear chriseaker,

Hope you're well. If the timing belt and/or tensioner fail, you face a very costly repair. Thus, I'd not drive the car, until the timing belt and tensioner have been replaced. The cost of doing these things is trivial, compared with the cost of a head re-build or engine replacement. I'd not delay even a day.

Do you know when the timing belt tensioner was last replaced? If you don't it is now time!!

Hope this helps.

Yours faithfully,

Spook

One quick and easy way to determine if the whine is accessory or timing mechanism sourced, is to remove the serpentine belt and run the engine. If the noise stops then you will know it is the serpentine, if not then the timing belts.

You don't state how many miles are on the car so I cannot even venture a guess.

DanR '94 964 356,000 miles (122,000 on the new engine)
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DanR

Sorry, it's 196500.