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  1. #1
    Join Date
    Jan 2012
    Location
    Vancouver
    Posts
    28

    Default Disconnect Haldex?

    I know I am going to get some flack over this but...

    I have to go on a long trip in a couple of days-about 1500 miles on dry roads.
    I have a 2007 XC70 with 138K miles on it. The Haldex has never been serviced that I know of. I have read so many horror stories about the cost of not servicing the Haldex I am wondering if I should disconnect the wires to the Haldex for this trip and get it serviced immediately upon return? It acted up briefly recently but seems to be working fine at the moment.

    Any informed advice?

  2. #2
    Join Date
    Jun 2013
    Location
    Northeast
    Posts
    521

    Default

    Do you have details when you say "It acted up briefly recently"?
    Is there a fuse which can be pulled to disengage the DEM as an easier alternative to disconnecting the wires?
    2007 XC70, 206,000 miles
    2002 V70XC, 130,000 miles, parts car

  3. #3
    Join Date
    Jan 2012
    Location
    Vancouver
    Posts
    28

    Default

    thanks for the response. A couple of weeks ago I noticed that I was getting front wheel spin on odd occasions-the rear wheels were not driving at all. This only lasted a couple of days and then all was fine.
    It certainly would be easier to pull a fuse! Anybody know which one?

  4. #4
    Join Date
    Jun 2013
    Location
    Northeast
    Posts
    521

    Default

    Check your owner's manual for a list of fuses and their location.
    My manual says fuses #23 and #27 in the cargo area are for All Wheel Drive.

    Are you sure your AWD is an issue? It will only be put to work in situations where your front wheels are slipping. Are you planning to "off road"?
    Ideally, you'd want to check for codes using Volvo VIDA/DiCE diagnostic software or an OBDII reader. If your AWD is failing/acting up, it should generate a fault code.
    2007 XC70, 206,000 miles
    2002 V70XC, 130,000 miles, parts car

  5. #5
    Join Date
    Aug 2017
    Location
    Pleasanton CA USA
    Posts
    413

    Default

    Pulling the control cable off the Haldex?....or cutting the 12V power to it? I've never heard of anyone doing this. It's a mechanical-hydraulic transmission, which relies on pressurized hydraulic fluid to squeeze between metal turbine parts so they don't directly touch each other. You have to have a pressurized fluid, or the metal parts will come into contact and wear quickly. You'd be disabling the fluid pump. The Haldex device was never intended to be operated this way.

  6. #6
    Join Date
    Jan 2012
    Location
    Vancouver
    Posts
    28

    Default

    Thanks for your response. So are you saying that the pump runs all the time in order that the "turbine parts" do not touch? That would seem to go against everything written that says that the pump activates in order to engage the rear diff?

  7. #7
    Join Date
    Aug 2017
    Location
    Pleasanton CA USA
    Posts
    413

    Default

    Quote Originally Posted by davidbir View Post
    Thanks for your response. So are you saying that the pump runs all the time in order that the "turbine parts" do not touch? That would seem to go against everything written that says that the pump activates in order to engage the rear diff?
    Under normal driving, the Haldex delivers about 10% of torque to rear wheels. That means it's engaged hydro-mechanically all the time, with the % torque delivered to rear wheels varying from 10-50%. There are many who have converted their AWD --> FWD, and all had to remove the prop shaft and Haldex. I'm speculating that if your idea worked to decouple the AWD cleanly, it would be the preferred method, and well-documented.

  8. #8
    Join Date
    Jan 2012
    Location
    Vancouver
    Posts
    28

    Default

    Interesting!

  9. #9
    Join Date
    Dec 2010
    Location
    Cumbria, UK. Maine USA.
    Posts
    494

    Default

    Why not just service the Haldex, rather than risk destroying it?, granted it is a PIA but most competent backyard mechanics can handle it.
    Current Junk: Couple of worthless rusty old clapped out Volvo bricks, XC70's 02, 04 & Countless P.O.S's, Rust buckets, Junk cars,( 50W Oily cesspool Sludge) Stolen and other assorted rubbish cars, 1928 Jed Clampett Tourer, (8 hole cast iron lump, original rust and decay, 40W Straight Bacon Grease),

  10. #10
    Join Date
    Jan 2012
    Location
    Vancouver
    Posts
    28

    Default

    We delayed the trip for a day and I did just that! I had to wait longer than expected for the fluid and filter to arrive but it is done.

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