89 740 whinning noise

nisan17 · Post by **nisan17** » 24 Dec 2011, 13:32

Merry Christmas Members,
I have some free time and wanted to do this before I forget. My 740 non turbo has 230k and runs like a champ still. My question today is, about two months ago, I started getting a whining/high pitch hum noise coming from under the car while at highway speeds. It sounded like it was coming from the rear somewhere, and as it got colder it sounds like its louder and coming from the trans area. When I let the car coast the sound goes away, and when I give it gas it returns. At first I thought it was tire hum. But I got the new tires in August and no hum then.
Anyone have an idea what it can be so I can address this before it turns out to be a disaster

?

Thanks in Advance,

nisan17 · Post by **nisan17** » 24 Dec 2011, 17:37

Thanks so much. Helps me to narrow down to focal point. I'm leaning toward Diff/trans output shaft bearing. I know what axle bearing failure sounds like and ujoint failure sounds/feels like.

Can I have my mechanic(because he has a hoist and is dry!!!) check out the possibilities, will he be able to tell/pin point same?

Thanks again,