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wierd noise- is it the gearbox?

  • 20-04-2012 9:38am
    #1
    bambera
    Registered Users, Registered Users 2 Posts: 356 ✭✭


    Hi.

    Was in my mothers car the other day, a 08 Astra. I have noticed a strange noise, nearly like the noise a PC Tower makes , kinda like an asthmatic wheeze. When accelerating it can't be heard as the noise of the engine covers it I assume, but take your foot off the gas and it can be heard. It's changes depending on the speed, and if I put my ear on top of the gearstick I can hear that it's coming from there.

    However, a friend pointed out to me that the gearbox is actually in the engine bay near the left wheel, so does that mean it's not the gearbox?

    If the car is coasting downhill in neutral, the noise is still there. My mother is old, and can't really hear it, but she had new disk brakes and pads fitted to the from about a month or so ago..would that be anything to do with it?

    I'm just hoping it's not the gearbox on the way out!..any checks I can do to confirm this? It's working perfectly, no grinding/clunks and is smooth and shifts into gear with no issues.

    Many thanks.


Comments

  • #2
    [Deleted User]
    Posts: 23,339 ✭✭✭✭ [Deleted User]


    bambera wrote: »
    ............ it's not the gearbox?

    If the car is coasting downhill in neutral, the noise is still there. ................

    Not the gearbox :)

    I'd be looking at the discs and pads for starters.


  • #3
    bambera
    Registered Users, Registered Users 2 Posts: 356 ✭✭bambera


    RoverJames wrote: »
    Not the gearbox :)

    I'd be looking at the discs and pads for starters.

    Thanks so much! I was getting worried as I was looking up some other opel forums and from what I read, gearbox noises don't stop when the car is put into neutral - I thought this didn't sound right but I'm no expert..

    My friend jacked up the car lastnight, and when the wheels are manually turned they make a slight metallic noise - like the pads were rubbing off the disks..we though that was the issue, until we tested all 4 wheels , and they all make this sound, so I'm guessing it's normal.

    We dropped it into Opel the other day- when we asked the young lad was it the gearbox he said it was hard to say and that it could be the bearings etc.. he said to see if the noise gets louder and come back. 100 euro ! and he said to come back next week and he would change the gearbox oil to see if that would help..more money! Really not sure where to start.
    Thanks for the feedback.

    Edit..this is the reading that got me worried..I know its a different car but he mentions the noise continues if the car is in or out of gear..and it was eventually diagnosed as the 'diff'..which is part of the gearbox I'm guessing, yeah?
    http://www.vxronline.co.uk/forum/archive/index.php/t-78073.html


  • #4
    [Deleted User]
    Posts: 23,339 ✭✭✭✭ [Deleted User]


    bambera wrote: »
    ..............

    We dropped it into Opel the other day- when we asked the young lad was it the gearbox he said it was hard to say and that it could be the bearings etc.. he said to see if the noise gets louder and come back. 100 euro ! and he said to come back next week and he would change the gearbox oil to see if that would help..more money! Really not sure where to start.
    Thanks for the feedback...................

    I'd go back and speak to the service manager and make the point you paid €100 for a next to useless diagnosis.


  • #5
    bambera
    Registered Users, Registered Users 2 Posts: 356 ✭✭bambera


    RoverJames wrote: »
    I'd go back and speak to the service manager and make the point you paid €100 for a next to useless diagnosis.


    will do.. I'll be back there next week. What is the 'diff' that is mentioned on that thread ? The symptoms I mention sound very similar to that guys, in that the noise remains in neutral..thanks


  • #6
    [Deleted User]
    Posts: 23,339 ✭✭✭✭ [Deleted User]


    http://auto.howstuffworks.com/differential1.htm


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  • #7
    bambera
    Registered Users, Registered Users 2 Posts: 356 ✭✭bambera


    RoverJames wrote: »
    http://auto.howstuffworks.com/differential1.htm

    Thanks- had a read of that, so would I be correct in saying the noise from a faulty diff would not stop when the car is moving in neutral? Also, from what I have read, if the diff is faulty, the gearbox has to be replaced..are they all one unit? Thanks


  • #8
    [Deleted User]
    Posts: 23,339 ✭✭✭✭ [Deleted User]


    Common practise would be to replace the gearbox, I'd be really surprised if it was your gearbox of diff tbh, the recent brake work might be less than a coincidence.


  • #9
    bambera
    Registered Users, Registered Users 2 Posts: 356 ✭✭bambera


    RoverJames wrote: »
    Common practise would be to replace the gearbox, I'd be really surprised if it was your gearbox of diff tbh, the recent brake work might be less than a coincidence.

    Ok..thanks. Sorry for all the questions but if you have the time..

    If the diff is faulty..what is the cheapest fix, will having the gearbox refurbished (bearings) fix this? There is a slight whirling noise when turning right and I'm told the wheel bearings are all good..after reading the info on the diff this sounds like it could be the diff?

    If the diff is faulty, will the noise be there regardless if you are in gear or neutral while the car is moving?

    thanks for your help, I will ask the mechanic to have a closer look at the disk brakes next time.


  • #10
    fasttalkerchat
    Registered Users, Registered Users 2 Posts: 5,652 ✭✭✭fasttalkerchat


    bambera wrote: »

    We dropped it into Opel the other day- when we asked the young lad was it the gearbox he said it was hard to say and that it could be the bearings etc.. he said to see if the noise gets louder and come back. 100 euro ! and he said to come back next week and he would change the gearbox oil to see if that would help..more money! Really not sure where to start.
    Thanks for the feedback.

    You paid 100 euro for someone to listen to it?
    I would have done that for a tenner...


  • #11
    bambera
    Registered Users, Registered Users 2 Posts: 356 ✭✭bambera


    fasttalkerchat wrote: »
    You paid 100 euro for someone to listen to it?
    I would have done that for a tenner...


    left it in to opel to diagnose the problem..they took the car in, took it for a drive and said that the noise was too quiet to say it was the gearbox for sure. They suggested replacing the oil. They checked the bearings etc to see if they were making the noise and we were told they were ok. Got charged the minimum 1 hours labour..I was told this before hand so although expensive, can't really complain.

    Should I bother replacing the oil as they suggest? they quoted 85 euro for this. Would this have any effect on a noisy differential? Its not the gearbox as I though, as Roverjames pointed out, if it was, the noise would not remain while in neutral.
    Cheers


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  • #12
    [Deleted User]
    Posts: 23,339 ✭✭✭✭ [Deleted User]


    bambera wrote: »
    .............

    If the diff is faulty..what is the cheapest fix, will having the gearbox refurbished (bearings) fix this? ................

    Dunno the cheapest fix tbh, a good 2nf hand gearbox might be cheaper than rebuilding your own, dunno though.

    If the noise gets worse when turning it might be wheel bearings rather than gearbox bearings.


  • #13
    Wetbench4
    Registered Users, Registered Users 2 Posts: 1,230 ✭✭✭Wetbench4


    When you had the car jacked up, did you spin the rear wheels to see if they made the noise?? The rear wheels won't be connected to your gearbox/diff.


  • #14
    bambera
    Registered Users, Registered Users 2 Posts: 356 ✭✭bambera


    Wetbench4 wrote: »
    When you had the car jacked up, did you spin the rear wheels to see if they made the noise?? The rear wheels won't be connected to your gearbox/diff.

    yep we manually spun all 4 wheels- all similar sounding, like the pads were rubbing off metal.

    Is the gearbox and diff one unit, ie. is the diff a part of the gearbox or is it a stand alone part that just works in conjunction with the gearbox? cheers


  • #15
    Wetbench4
    Registered Users, Registered Users 2 Posts: 1,230 ✭✭✭Wetbench4


    bambera wrote: »
    yep we manually spun all 4 wheels- all similar sounding, like the pads were rubbing off metal.

    Is the gearbox and diff one unit, ie. is the diff a part of the gearbox or is it a stand alone part that just works in conjunction with the gearbox? cheers

    Im not a mechanic, i wouldn't know anything about an astra gearbox, but if the noise is coming from the rear wheels too then you can probably rule out the diff and gearbox because they only concern the front wheels on a front wheel drive car.


  • #16
    bambera
    Registered Users, Registered Users 2 Posts: 356 ✭✭bambera


    Wetbench4 wrote: »
    Im not a mechanic, i wouldn't know anything about an astra gearbox, but if the noise is coming from the rear wheels too then you can probably rule out the diff and gearbox because they only concern the front wheels on a front wheel drive car.

    ok thanks. The noise I'm concerned about is coming from the front of the car. Don't think its anything to do with disk brakes/pads as all 4 wheels make the same noise when manually spun.


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