97 850 screaming schrill

I've purchased a 97 850 automatic with 114k, through a mechanic who I
feel was trustworthy and knowledgeable. He was selling it for a
client and did the maintenance on the car since new.
He put a new air pump on the car from Volvo prior to the sale, but
said it was "screaming". So before I took possession he replaced it
again with another one from Volvo, but with the same result.
I do not know if he changed the relay or the SAS valve, but there is a
shrill coming from the front of the car. When I say a shrill I mean I
can hear the noise from 50 to 70 feet away.
It seams to come from center, to just off to the passenger side on the
front of the engine.
It goes away under load, but is fairly constant at idle wether in
neutral or drive.

 

I haven't heard the sound and I'm not a mechanic but I would question
the state of the timing belt/tensioner/water pump.

 

Yep most likely a loose/worn belt, or in rare cases a pulley bearing has
gone dry.

I've have had an 850 for a long time, never noticed an Air Pump, where is
it?

 

--

I had this happen on my '96 850 some years ago, it was the rubber bend on
the vacuum line from the end of the inlet manifold to the crankcase
ventilation system. On the timing belt side of the motor under the inlet
manifold just below the thermostat housing. A real bugger to get at, let
alone see. The rubber bend goes "soggy" and gets a hole in it and the
engine vacuum makes it act as a "musical instrument" reed. It also was
really loud. I also got a
fault code, forget now the number but something along the lines of "engine
running rich under mid throttle".

I replaced mine with a piece of appropriately sized rubber tube the first
time and the second time (it got soggy again) due to the difficulty in
getting my hands in, I re-routed the vacuum line (hard nylon) above the
manifold to the crankcase ventilation system on the other side. I tied it
to the fuel rail.

I makes a scary noise but it isn't all that serious.

To confirm, try and poke the bend with something (like a stick) while the
noise is there.
It should change it.

I posted this a few days ago, but it never appeared....

barry

 

Barry was right. I hit the hose with a pen, and the whistle changed
tone dramatically.
Thanks again Barry