1990 240 wagon "whistling" at 40

[edelmatt]

I hope I too am whistling at 40... But I really wish my Volvo wouldn't.

My 240 has been parked all summer since the AC is broken. My daughter just turned 16 so she started driving it to school. Just about a week later and the car has developed an exciting whistle. When you get the car up to 40mph, the whistling sound starts up. The frequency or volume of the whistle doesn't seem to change based on the speed. It's either "on" or "off". Once I brake back below 30 or so, it stops (until I again get up to 40).

My thoughts are the whistling is a vacuum leak, a bearing going bad, or something related to the transmission. The bad bearing seems unlikely because the frequency of the whistling doesn't change. If it is a bearing I would expect the frequency to increase with increased speed. It does not. I don't really know how to zero in on the problem any more than that. Has anyone experienced this? Or does anyone want to look into their Swedish Crystal Ball and opine?

Thanks in advance!
Matt

[billofdurham]

I had a whistle on my 740 under the same conditions. I eventually traced it to the end of a drain low down on the bulkhead (firewall). It was rubber, shaped a bit like a duck's beak but the end was, supposedly, closed in the middle allowing water to come out at the sides. The rubber had hardened and the hole stayed open allowing the wind-flow to enter. I taped a small polythene bag over the end after putting a very small hole in the bag. This allowed water out but stopped the wind getting in. In four years I had to change the bag once but had no more whistle!

I hope your problem is that easy to fix.

Bill.

[edelmatt]

Hi Bill,

Thanks for your response. I should have done a search before posting this as there are a lot of threads already related to 240's whistling at a certain speed. Some of them mentioned low transmission fluid as a possible culprit. Though I changed and measured the tranny fluid last summer, I went ahead and rechecked the level. It seemed fine, but I got out a bubble level to make sure the car was parked level. Even though by my eye it appeared to be parked level, the bubble indicated it was not. Once I was able to make a proper measurement I saw that the fluid was pretty far from full. I added enough to get the level up into the "high" range and no longer hear the whistle after a few days of driving. So that apparently was it in this case.

The learning from this is that even a very slight incline will throw off the tranny fluid measurement.

Thanks again.
Matt

[billofdurham]

Thank you for the update.

Bill.