Diesel 240: Odd noise

Discussion in 'Volvo 240' started by PT in OR, Nov 14, 2007.

  1. PT in OR

    PT in OR Guest

    Well, I've had no luck figuring this problem out. Maybe someone here
    can help.

    '82 240 Diesel. Ever since I got the car, there has been this noise
    that sounds like pre-ignition would in a gas car and it happens at the
    same times it would in a gas car-accelerating, on hills, etc. I
    checked the exhaust and valves and all that. Here's where it gets
    weird:
    The problem is bad with #2 diesel.
    The problem is nonexistent on bio-diesel.
    The problem is worse on vegetable oil.
    At first I thought it was the extra lubricity of the bio-fuels, but it
    gets bad on the vegetable oil (yep, have the kit).
    Any ideas what this might be? Someone suggested the vacuum pump, but I
    have trouble believing a pump noise would be effected by the fuel.
    Thanks!
     
    PT in OR, Nov 14, 2007
    #1
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  2. PT in OR

    Roadie Guest

    On Nov 14, 8:43 am, PT in OR <> wrote:
    > Well, I've had no luck figuring this problem out. Maybe someone here
    > can help.
    >
    > '82 240 Diesel. Ever since I got the car, there has been this noise
    > that sounds like pre-ignition would in a gas car and it happens at the
    > same times it would in a gas car-accelerating, on hills, etc. I
    > checked the exhaust and valves and all that. Here's where it gets
    > weird:
    > The problem is bad with #2 diesel.
    > The problem is nonexistent on bio-diesel.
    > The problem is worse on vegetable oil.
    > At first I thought it was the extra lubricity of the bio-fuels, but it
    > gets bad on the vegetable oil (yep, have the kit).
    > Any ideas what this might be? Someone suggested the vacuum pump, but I
    > have trouble believing a pump noise would be effected by the fuel.
    > Thanks!


    The way you describe it the sound it apparently increases with speed
    so it sounds engine related. Do you have an exhaust leak somewhere?
    If not then it sounds more serious. If the car was converted to run
    on fuels other than diesel is it possible that the installer screwed
    something up? Maybe the timing?
     
    Roadie, Nov 16, 2007
    #2
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  3. PT in OR

    Rob Smith Guest

    On Wed, 14 Nov 2007 05:43:44 -0800, PT in OR wrote:

    > Well, I've had no luck figuring this problem out. Maybe someone here
    > can help.
    >
    > '82 240 Diesel. Ever since I got the car, there has been this noise
    > that sounds like pre-ignition would in a gas car and it happens at the
    > same times it would in a gas car-accelerating, on hills, etc. I
    > checked the exhaust and valves and all that. Here's where it gets
    > weird:
    > The problem is bad with #2 diesel.
    > The problem is nonexistent on bio-diesel.
    > The problem is worse on vegetable oil.
    > At first I thought it was the extra lubricity of the bio-fuels, but it
    > gets bad on the vegetable oil (yep, have the kit).
    > Any ideas what this might be? Someone suggested the vacuum pump, but I
    > have trouble believing a pump noise would be effected by the fuel.
    > Thanks!


    Since it changes with the type of fuel and the degree of load on the
    engine, I'd almost have to guess that it is related to combustion chamber
    deposits and heat. My guess is that the Bio-diesel runs a bunch cooler,
    hence the noise disappearing, while the SVO runs the hottest. Have you
    pulled your injectors to see if there are any built-up deposits on them?

    I agree with you regarding the vacuum pump.

    +++++
    Posted via Debian GNU/Linux
    www.debian.org
    +++++
     
    Rob Smith, Nov 27, 2007
    #3
  4. > I agree with you regarding the vacuum pump.

    The vacuum pump can make a lot of noise! Mine does sometimes. Sounds like
    knocking on metal. I don't know what to do about it, and it disappears just
    like that after a few moments.

    --
    Regards, Jakob :)
     
    Jakob Griffel, Dec 3, 2007
    #4
  5. > At first I thought it was the extra lubricity of the bio-fuels, but it
    > gets bad on the vegetable oil (yep, have the kit).


    Where can I read more about this bio-fuel-kit?
    Do you have a link for me?

    --
    Regards, Jakob :)
     
    Jakob Griffel, Dec 3, 2007
    #5
  6. PT in OR

    Rob Smith Guest

    On Mon, 03 Dec 2007 14:34:32 +0100, Jakob Griffel wrote:

    >> I agree with you regarding the vacuum pump.

    >
    > The vacuum pump can make a lot of noise! Mine does sometimes. Sounds like
    > knocking on metal. I don't know what to do about it, and it disappears just
    > like that after a few moments.
    >


    Yeah, but does the sound change depending on the type of fuel that you're
    running?
     
    Rob Smith, Dec 3, 2007
    #6
  7. PT in OR

    Rob Smith Guest

    Rob Smith, Dec 3, 2007
    #7
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