The other day I noticed what I believe to be a new noise. If the engine is revved real high (works at idle, easiest to detect, get someone outside by exhaust and someone to rev) like 4000 RPMs as you back off the throttle you can hear a real deep burble (every time) reminiscent of an American V8, while this sounds cool I don't expect it from my turbocharged white engine.

Anyways, anyone know what causes this? does it indicate a problem? is it normal and I just never noticed it before?

It's somewhat disconcerting since I don't ever remember hearing it before.


Thanks,
Scott Silverman
--
'98 S70 T5-M - Tropic Green w/ tan, Spoiler, Fog Lights, CD-6/CD-3 Changer, External Amp, Cold Weather Pkg, Sunroof

It's the I5 configuration that causes it. NA I5 Volvo's accentuate this sound even more. Just listen as an NA 850 or _70 drives by. I5 inherently burble. If you get a high flow large diameter exhaust, the burble becomes even more prominent. In fact, I LOVE driving my 4th gen Maxima while my dad drives the 850T. The 850 has a pretty nice T-304 3" downpipe 2.5" cat back exhaust on it, and boy does it sound good.

If you are just starting to hear it recently, it's probably the exhaust piping, baffles and glass pac deteriorating.

When the T5-M was first imported to the US, the motoring press described it as being quiet and civilized 99% of the time but "screaming like an enraged wookie" when one nails the throttle.

I like the sound. (Unlike the million squeaks and rattles.)

-Phil Punxsutawney

Mine does that - and your right it does sound kinda cool.
Most likely nothing to worry about.

DG
--
1998 S70 T5M

I have never noticed this this on my 98 T5M. I'll have to give
it a try.

I thought maybe the turbo bypass valving might be your cause
since closing the throttle would activate it; but, if you are not
moving there would not be much boost built up so that would probably
not be it.