Whistling Exhaust...?

[Sturgey]

I've had a strange whistling sound coming from the exhaust of my 1989 2.1 dj for the past few months now.
It seems to start when I give her some gas to bring her up to speed, or when I put my foot down to get her up the numerous steep hills here in the valleys, but more annoyingly, it seems to come in at my motorway cruising speed of about 55 / 60 mph.
With only light throttle use, it doesn't make any noise, but as soon as I give it approx. half throttle, it starts to whistle, only to disappear again if I bury the throttle to the floor.
I've had her up on the ramps during the MOT and the fitter said that there were no leaks in the exhaust system, no seals blowing and that the sound, (which sounds like a "chirp" when blipping the throttle) was coming from the exhaust pipe itself. ?.?.?
The petrol engine is fuel injected and doesn't have a turbo...it's done 130 thou, and apart from this annoying soundtrack, seems to be running fine.
Any ideas or remedies would be greatly appreciated...

Cheers,

Sturg.

[California Dreamin]

I've seen it when the insides of the silencer corrode allowing the fibre glass wadding to escape blocking the gas ways. Pressure builds up and an intense hissing noise ensues.

Martin

[kevtherev]

Is the alternator making the noise?
take the belt off and run the engine for a minute and see if it's still there.
Also if it whistles when you floor it, that could be an induction leak too

My 2.1 whistles I thought they all did

[California Dreamin]

Mine does with a new alternator belt fitted...seems to disapear after a few thousand miles....but throttle load doesn't make any difference.
Could be an induction noise though, like you say.

Martin

[jason k]

My MV whistled , it sounded lovely!!

[California Dreamin]

Non, je ne regrette rien....no regrets Jason?

Martin

[jason k]

Nah Martin, have you not seen the new karmann? A proper gin palace!!!!
My old westy was the prettiest van I owned though