Hello, folks!

My car's making a strange sound, and it's coming from the turbo.

It spools up like normal, making the regular sounds, but if I enter the boost area of the meter and then let my foot off the gas suddenly, dropping from boost to vacuum, a strange growling sound comes from what I suspect is the turbo itself, but could be anything else in the exhaust side of the car. There's a corresponding slowing down of the needle when it makes the sound.

What the heck is that sound? It's gotten worse; it used to only make it in the first quarter of the vacuum part of the meter, but now it does it almost all the way down--from the moment it enters vacuum to the moment it finishes slowing.

Also, the car runs fine; again, the turbo spools up perfectly, without making any abnormal noises, and there's plenty of boost to go around.

I'm wondering if there's perhaps a lack of lubrication; there's been an oil leak that I haven't been able to get to yet that keeps me putting in a quart every two hundred miles or so, so the oil is pretty regularly cycled.

But I don't know at all what the sound could be, and it worries me. Please help a worried Volvo owner.

Thanks,

Volfro

'85 740 Turbo, 160000 mi on the engine and 260000 on everything else