I have a 1988 Volvo 240 GL automatic transmission with 130,000 miles. It’s been well maintained and owned solely within our family over the past 14 years. About 18 months ago at 120,000 miles I had the 125,000 mile maintenance/check-up; however, the engine and transmission have not been replaced. Since September 2000, I’ve only put 4000 miles on it. In November 2000, I was driving on the freeway in very cold weather, roughly 25 F, (I moved from California to Washington D.C. that summer) and noticed that the car began to make a loud, relatively high pitched sound which grew louder the longer I drove sounding as if something would explode if I drove for an extended period of time at high speeds. Based on a not so scientific description of sounds, I would say it is a "whine" but perhaps also a subtle, high pitched, but loud "vibration." It sounds like the sound is coming from the right side of the car. It also sounds like the sound is from the engine and not from parts rubbing on the chassis or frame--although I could be wrong here. I slowed down to less than 50 mph and the sound disappeared. I did not drive on the freeway again that winter but noticed that while driving on city streets at high speeds, it sounded like the noise would appear again.

A few months later (in the late spring and summer of 2001) when it was warm again, I drove on the freeway and there was no sound at all. In fact, I drove several times on the freeway at high speeds and did not notice the sound at all.

Then, when the weather was cold again this winter, in January 2002, I drove on the freeway and the same sound again reappeared. Now, when I drive at lower speeds, the sound appears as well but it is not as loud.

I notice no unusual sounds in idle or when I rev the car in park/neutral. I've driven the car across country five times and had no problems at all with freeway driving although it was always during the summer. Does anyone have further thoughts on what this problem might be and why cold weather seems to cause it?