Whistle sound coming from Volvo V70 XC?
July 8, 2011 2:54 PM   Subscribe

Volvo V70 XC whistle on acceleration. What's up with that?

Hi there. My 2002 V70 XC is making a new and alarming whistling only sometimes when I accelerate. Like blowing across the top of a bottle. I generally take my car to a jack of all trades mechanic, but I wonder 1) if this is even a problem, 2) whether I need to have it check out by a Volvo pro (read: expensive). Has anyone else experienced this?

Another thing that's happened lately is that when I lift my foot off the brake, I hear a hissing. Like a bellows coming open or closing. These noises may not be related, but perhaps?

No change in operation of the car that I've noticed.
posted by ascheele to Travel & Transportation (7 answers total)
I experienced something similar on an older Volvo, but it went away on its own.

If it happens when the car is stationary, you may be able to isolate the problem to a loose vacuum hose, PCV valve, or something like that.
posted by swift at 3:15 PM on July 8, 2011

Look under the hood. There ought to be a rubber tube approx 3" in diameter coming from the air filter area going into the engine itself. It probably has fallen loose.
posted by gjc at 3:28 PM on July 8, 2011

Vacuum hose problems do not go away on their own. We were told by a mechanic that the hose hanging below the engine wasn't serious, and ended up with a carburettor full of sand.
posted by dunkadunc at 3:32 PM on July 8, 2011

When you accelerate, the torque causes the engine twists in its motor mounts, which means things like intake hoses and exhaust ductwork have to be able to flex a bit. If you've got a small leak, it can open up and cause noise only under those circumstances. The hissing noise when you take your foot off the brake sounds like a vacuum leak in the power brake booster. Neither of these things should require any kind of specialized knowledge or heroic diagnostic skill.
posted by Rhomboid at 3:52 PM on July 8, 2011

On the other hand, taking the car to a Volvo specialist will mean that if there is a serious problem it is more likely to be found early than at a general mechanic.
posted by twblalock at 5:07 PM on July 8, 2011

My guess is that it is a particular vacuum hose - brake booster is the likely culprit, as you can hear it in the cabin, and would make noises when you use the brakes. I am not super familiar with your car, but this conversation here and here indicates it is a known issue for your year and sadly appears to be a pricey fix.

Apparently the noise will get worse and the brakes will become difficult to use- a pretty major issue so get it checked out.

Also - on many modern cars most vacuum hose failures would quickly result in a engine code lighting up.
posted by zenon at 7:57 PM on July 8, 2011

It sounds like intake plumbing has developed a leak. This can lead to debris entering the intake path and damaging your intake components or turbo, both of which are pretty expensive.

My old Volvo 850 Turbo (similar T5 engine to your X70) had an intake hose completely break loose and the car was nearly undriveable. Not long afterwards the turbo started experiencing issues.
posted by tmt at 12:12 AM on July 10, 2011

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