Rattle/flutter on low rpm boost/acceleration

[AnneTeak]

Hello

I wonder if you may be able to help... When accelerating from a low RPM (before boost?), between 1500-2000 RPM the car makes a rattle/flutter noise, almost metallic in sound.

The noise only occurs under moderate/heavy acceleration (i.e. not just very lightly accelerating up) and is most noticeable when in a high gear and low RPM.

Is it turbo related, belts perhaps? There is no noise on idle (or when accelerating when idle).

The car is a Volvo V60 D5.

Thanks

[Auntieroll]

Detonation?

[McVities]

Auntieroll said:

Detonation?

Was my first thought, until I got to the bit where the OP says D5........didn't know a diseasel could detonate, I thought that was their M.O?

[AnneTeak]

Thanks for the replies guys, if detonation sounds like this I doesn't sound the same. It's more like a squeak noise and like something spinning at speed, similar to this noise in pitch, although I'm not sure its the belt.

Edited by AnneTeak on Tuesday 28th March 14:49

[GreenV8S]

Waste gate flutter, or something like that?

[AnneTeak]

Thanks, is there anyway to test the wastegate? Assuming the wastegate should be silent under load/acceleration?

The noise starts 1400 to 2200 RPM ish and sounds a little like a fan belt slipping. I would say marginally worse when cold, but that might be an illusion.

[Auntieroll]

McVities said:

Auntieroll said:

Detonation?

Was my first thought, until I got to the bit where the OP says D5........didn't know a diseasel could detonate, I thought that was their M.O?

Mea culpa, I didn't register the D5 either!! In my defence it was very late when I posted.

[Mr2Mike]

This kind of noise is very often caused by loose or broken heatshields on the exhaust, usually around the turbo and and cat.

[AnneTeak]

Thanks guys. I've uploaded a video here, it's hard to hear but is from 4 second onwards. Sounds almost like a belt noise you sometimes here on cars, but only lasts around 1500-2200rpm.

Edited by AnneTeak on Tuesday 28th March 21:44

[anonymous-user]

My sisters XC90 made a somewhat similar noise, turned out to be a knackered AC pump. See if the noise goes away when you turn the AC off!

[ZX10R NIN]

Is the car mapped? The reason I say this is because if it is then it'll be wastegate, also what condition is your air filter in?

[philthy]

Hate to resurrect an ancient thread, but did you have any success in finding the cause of this OP?
My petrol C70 is doing exactly the sane thing you describe.
The noise is coming from the right hand side of the engine, possibly a pulley/belt noise. A local mechanic suggested that it might be the alternator overun bearing?

[Mattaps]

ZX10R NIN said:

Is the car mapped? The reason I say this is because if it is then it'll be wastegate, also what condition is your air filter in?

Hi, I have a rattling sound coming from the wastegate area, most noticeable when I take my foot off the accelerator. Pretty sure power is lacking too. The previous owner of my Saab 9-3 remapped the engine so I am intrigued to know more about the connection between the two. Has overboosting damaged the turbo? If I get the turbo fixed is the same thing likely to happen again; meaning should look to get the remapping reversed? Many thanks for any help.

[ZX10R NIN]

In the case of the D5 when they're mapped you can sometimes hear the wastegate flutter under medium to high acceleration. If your wastegate is rattling that's a different issue.