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Strange Sunroof Problem V70-XC70 1998

posted by  someone claiming to be Bill Nugent on  Wed May 2 04:58 CST 2001 [RELATED]

No leaks, squeaks or tweaks. Now for something completely different...Anyone else seen (or felt) this?

When the roof is open and we are cruising between 30-35 mph, like dring around town, there is a pulsation almost a trobbing in the air coming thru the roof. The flow is hitting a natural frequency and exciting the air in the cabin. The pressure fluctuation is enough to cause your ears to be uncomfortable. Both my wife and I noticed it and my children complained about it.

I know its a flow problem because 1. I am a ship designer and deal with ventilation systems and ship hydrodynamics all the time and 2. because the problem goes away as you close the sunroof part way or go faster or slower and alter the flow and excitation.

The problem has occurred when the air temp is about 65 degF. I did not see the prob in the beginning of march when I was racing around with the top open in the cold weather (and air density was higher) and occurs to a lesser extent now that the weather is almost hot here in NY/NJ (85-90 deg).

I know the prob will disappear if I put the wind deflector on, but the car looks better w/o it (imho).

Thanks,

Bill





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