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    1. #1

      Humming sound when idling

      Hi everyone,

      When my car is idling there's a kind of a rough humming sound coming from th eengine area. Sounds like maybe a misbalanced fan or loose belt? It usually goes away once I press the gas and start moving, but it will also come back if I'm coasting without my foot on the gas. It's been doing this for several weeks now and seems to be getting more consistent.

      Is this something I should worry about or should I just bring it up during my next service?

      My car: 2005 S40, T5 AWD, ~50k miles

      Thanks


    2. #2
      Moderator tmtalpey's Avatar
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      Re: Humming sound when idling (barnacle)

      Try this - at idle, open the hood and pull out the dipstick just one inch. If the sound changes, remove the dipstick and lightly put your finger over the tube. If you feel air moving, take it in immediately - the oil trap diaphragm has a leak.

      If it doesn't change, then put it back and try to identify the area of the noise. Is yours a manual or automatic?

      Tom.

      2005 V50 T5 AWD 6MT w/Heico tune, Heico exhaust, Bell intercooler, IPD TCV, Viva CBV, Elevate rear swaybar, Snabb shift kit, etc.
      2004 XC90 2.5T AWD
      1956 PV444 complete, running
      1956 PV444 very original, very rough

    3. #3
      It is a manual 6 speed.

    4. #4

      Re: Humming sound when idling (tmtalpey)

      I will try the dipstick test when I gte home from work tonight. Hopefully it's not a leak in the oil trap diaphragm. I think I've read about people having this problem before, I tried to do a search but didn't come up with anything. Is the fix for this very involved?

    5. #5
      Moderator tmtalpey's Avatar
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      Re: Humming sound when idling (barnacle)

      I believe it's around $600, but many have argued it's a design defect and frankly, it is. It only affects some cars though.

      It's only a guess on my part, remember. I can make lots of others!

      From the FAQ thread at the top of this forum:
      http://forums.swedespeed.com/zerothread?id=82252
      http://forums.swedespeed.com/z...35080

      Tom.

      2005 V50 T5 AWD 6MT w/Heico tune, Heico exhaust, Bell intercooler, IPD TCV, Viva CBV, Elevate rear swaybar, Snabb shift kit, etc.
      2004 XC90 2.5T AWD
      1956 PV444 complete, running
      1956 PV444 very original, very rough

    6. #6
      Member volvoNB's Avatar
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      Re: Humming sound when idling (barnacle)

      If the car sounds like this
      http://forums.swedespeed.com/zerothread?id=80861

      then your car has been invaded by aliens. Complain to the dealer. It seems to be a common known problem with no permanent fix besides replacing the part. RedV50 got his replaced under warranty even though he was slightly past 50k.

      2005 S40 T5 BSR Stage 3

    7. #7

      Re: Humming sound when idling (volvoNB)

      I made an appointment with the dealer to bring my car in tomorrow morning. I am at about 50,300 miles but I purchased the extended warranty to 100,000 miles, so hopefully it's not an issue. After reading all of the threads about this I'm a bit worried... ugh.

      Problems with my car so far...
      Steering wheel locked up - within first couple of months of owning the car, stranded me at the store, had to replace the entire steering wheel assembly.
      Oxygen Sensor went out - about 2 months ago, seemed like an easy fix
      Screaching humming problem -

      I'm also not too imressed with all the road noise. On the freeway I have to turn up the volume pretty loud to understand what anyone is saying on any sort of talk radio.

      Other than that I really like the car, especially how it drives.

      Oh well, I'll probably keep it till just before the 100k warranty is up. Not sure if I'll get another Volvo or not after that. This was my first new car, so I don;t really have anything to compare it to.


    8. #8
      Moderator tmtalpey's Avatar
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      Re: Humming sound when idling (barnacle)

      Did you have any pressure at the dipstick tube? If not, it probably isn't the diaphragm...

      Anyway, couple of notes on the other issues - the road noise, what tires are you running? Surely not the OEMs, if so there's yer trouble. what pressure?

      Oxygen sensor - 50k miles is early, 100k+ is more typical. Most modern cars have pretty stringent O2 sensor needs, this is by no means restricted to Volvo. Also, Volvo uses the same sensors as everyone else. Was this the front or rear sensor? What happened to make them replace it?

      Tom.

      2005 V50 T5 AWD 6MT w/Heico tune, Heico exhaust, Bell intercooler, IPD TCV, Viva CBV, Elevate rear swaybar, Snabb shift kit, etc.
      2004 XC90 2.5T AWD
      1956 PV444 complete, running
      1956 PV444 very original, very rough

    9. #9

      Re: Humming sound when idling (tmtalpey)

      OK, I checked the dipstick tube. There was no pressure noticable and loosening it had no effect on the sound.

      I cancelled my appointment and I'm not sure what to do now. I have another checkup in about 2000 miles, maybe I should just wait and bring it up then? I don't want to have to pay for diagnostics and repairs if it's something that's not serious and not under warranty...

      I changed out the stock tires at around 35k miles and replaced them with Bridgestone Potenzas 225/45/17. Handling is much improved, and so is noise but it's still not down to what I would like. But a good portion of the noise problem is air around the windows.

      I believe it was the front O2 sensor but I'm not 100% sure on that. The check engine light came on and I started getting significantly worse gas mileage (I had to drive it about 200 miles home cause I was on a road trip at the time).


    10. #10
      Moderator tmtalpey's Avatar
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      Re: Humming sound when idling (barnacle)

      Ok, that's actually good. Where do you think the hum is emanating from then? Right/left/front/back/bottom of the engine area (with the hood open)? If it doesn't happen at a standstill, that's an even bigger hint.

      Tom.

      2005 V50 T5 AWD 6MT w/Heico tune, Heico exhaust, Bell intercooler, IPD TCV, Viva CBV, Elevate rear swaybar, Snabb shift kit, etc.
      2004 XC90 2.5T AWD
      1956 PV444 complete, running
      1956 PV444 very original, very rough

    11. #11
      I can hear it very well from inside the car, it seams to be coming from the center. Sometimes it's accompinied by a very high pitch single tone ringing. That pitch is high enough to where my parents can't hear it. With the hood open it's harder to locate, I'm not sure if it's because the tone sounds different when it's not coming through the dash or what.

      It doesn't necessarily turn off when the car is moving, but it will when I'm accelerating. Then when I start coasting again it comes back. It almost sems like the sound goes away when the turbo kicks in? I haven't tried reving the engine in neutral, I will have to check on that.


    12. #12
      It's always there when at standstill.

    13. #13
      Moderator tmtalpey's Avatar
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      Re: (barnacle)

      Ok now it sounds turbo-related, but it's funny that it happens when you back off and not when you accelerate, I'd think air leak otherwise. It almost sounds like an issue in the turbo itself, possibly the compressor bypass or wastegate. Does the car have any performance issues?

      Tom.

      2005 V50 T5 AWD 6MT w/Heico tune, Heico exhaust, Bell intercooler, IPD TCV, Viva CBV, Elevate rear swaybar, Snabb shift kit, etc.
      2004 XC90 2.5T AWD
      1956 PV444 complete, running
      1956 PV444 very original, very rough

    14. #14

      Re: (tmtalpey)

      I was thinking that last time I had my car in and they gave me loaner the loaner seemed a bit more powerful. But it was a 2007 s60 2.5T automatic, so I wrote it off to just differences in how it drove (ie it downshifted when I accelerated). Part of me wants to say my car isn't as peppy as it used to be, but it might just be the fact that I got used to it...

      So for performance issues I would say minor if there at all. Or if it happened it happened slowly over time so I didn't notice a big drop off.

      Gas mileage seems pretty same as always.


    15. #15
      Moderator tmtalpey's Avatar
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      Re: (barnacle)

      At this point, if you can hear it consistently I think you should take it in, at least to demonstrate it to a service advisor and get an opinion first-hand whether to make an appointment. If it's a turbo issue. a simple test will prove it.

      Tom.

      2005 V50 T5 AWD 6MT w/Heico tune, Heico exhaust, Bell intercooler, IPD TCV, Viva CBV, Elevate rear swaybar, Snabb shift kit, etc.
      2004 XC90 2.5T AWD
      1956 PV444 complete, running
      1956 PV444 very original, very rough

    16. #16

      Re: (tmtalpey)

      Tom, thanks for all your help.

      I am leaving on vacation, so I will probably take it in when I get back after the new year. I will definitely let you know what the results are.

      -John


    17. #17

      Re: (barnacle)

      Is it caused by engine mount broken? I did my engine mount replacement at 76,000km.
      If the engine mount broken, you can see the oil leak around the engine mount.

    18. #18
      I am unaware of any oil leak, at least none exists to the point of dripping on the ground.

    19. #19

      Re: (barnacle)

      You will not see the oil drop on the ground if the engine mount leak. Just check the engine mount near timing belt, under the coolant tank.

    20. #20

      Re: (Jacky888)

      My car is starting to hum really randomly and in the morning when I take off for work. wtf? It sounds like Bubb Rubb when he says WOO WOO!