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  1. #1
    Join Date
    Oct 2018
    Location
    Glasgow Scotland
    Posts
    2

    Default Haldex issues. 2005 xc70

    Hi all, recently purchased xc70.No com to dem. Trying to remove dem from diff but all allen keys siezed. Have had to remove complete Haldex to get access. Have drilled heads off allen bolts but the remainder of bolts corroded to aluminium of dem housing. Question is if i damage unit and have to get used replacement can it be programmed to car easily or is it a dealer job. Any advice appreciated.

  2. #2
    Join Date
    Dec 2009
    Location
    GA
    Posts
    1,420

    Default

    Quote Originally Posted by Steviesstag View Post
    Question is if i damage unit and have to get used replacement can it be programmed to car easily or is it a dealer job.
    The DEM has to be programmed to the car, and a dealer can not make a used one work.

    Check here for a solution

    https://xemodex.com/us/differential-...olvo-services/

    Keep in mind that a bad haldex pump can fry the DEM, and will fry the new DEM if not replaced first

  3. #3
    Join Date
    Feb 2013
    Location
    Boston, MA
    Posts
    1,196

    Default

    Quote Originally Posted by hoonk View Post
    Keep in mind that a bad haldex pump can fry the DEM, and will fry the new DEM if not replaced first
    They usually die because water finds its ways around the seal and gets inside to the PCB.









    That one was repaired (replaced one tiny corroded SMD resistor) and resealed:





    Not too difficult actually.
    2002 V70 (sold)
    2005 XC70 (Telos Road took it. Did a chassis swap)
    2016 XC60 (sold, P.O.S.)

  4. #4
    Join Date
    Feb 2013
    Location
    Boston, MA
    Posts
    1,196

    Default

    Quote Originally Posted by Steviesstag View Post
    Hi all, recently purchased xc70.No com to dem. Trying to remove dem from diff but all allen keys siezed. Have had to remove complete Haldex to get access. Have drilled heads off allen bolts but the remainder of bolts corroded to aluminium of dem housing. Question is if i damage unit and have to get used replacement can it be programmed to car easily or is it a dealer job. Any advice appreciated.
    Same model year DEM will work as is.
    2002 V70 (sold)
    2005 XC70 (Telos Road took it. Did a chassis swap)
    2016 XC60 (sold, P.O.S.)

  5. #5
    Join Date
    Feb 2013
    Location
    Boston, MA
    Posts
    1,196

    Default

    Also cut the Haldex body with a Dremel along the bolt and then "fix" the slot with JB Weld. New bolts do need some copper grease, otherwise in 5 years they'll be glued too.



    2002 V70 (sold)
    2005 XC70 (Telos Road took it. Did a chassis swap)
    2016 XC60 (sold, P.O.S.)

  6. #6
    Join Date
    Jun 2013
    Location
    Northeast
    Posts
    584

    Default

    I'm planning to remove DEM and replace the temp/pressure sensor to correct a DEM-007 code. I'll see if I have issues with those allen bolts. Steviesstag, if I understand correctly, the heads of the bolts snapped off when you tried to remove them with an allen key? Any luck with trying a penetrating oil? This sounds like it could be a "fun" repair.
    2007 XC70, 206,000 miles
    2002 V70XC, 130,000 miles, parts car

  7. #7
    Join Date
    Feb 2013
    Location
    Boston, MA
    Posts
    1,196

    Default

    Quote Originally Posted by Xfingers View Post
    I'm planning to remove DEM and replace the temp/pressure sensor to correct a DEM-007 code. I'll see if I have issues with those allen bolts. Steviesstag, if I understand correctly, the heads of the bolts snapped off when you tried to remove them with an allen key? Any luck with trying a penetrating oil? This sounds like it could be a "fun" repair.
    You may need to drill a slot on the bolt head for a flat screwdriver. Be careful, it's very easy to cut a hole in the DEM cover!

    Given your mileage, the bolt may be diffused to Haldex too badly, in such case the whole unit needs to be taken out. I was unable to turn one bolt even with a pipe wrench, thus had to cut a slot along the bolt.
    2002 V70 (sold)
    2005 XC70 (Telos Road took it. Did a chassis swap)
    2016 XC60 (sold, P.O.S.)

  8. #8
    Join Date
    Jun 2013
    Location
    Northeast
    Posts
    584

    Default

    Thanks for the info, vtl. So after you drilled a slot in the bolt head, the flat screwdriver allowed you to deliver enough torque to break the bolt free. Geez, I would think a 4mm allen key would give enough bite to turn that bolt. I guess you guys are saying the allen key slips and strips out the head. The part is out for delivery so I'll probly give it a go next week. I've got Deep Creep, PBBlaster, Acetone + ATF. I'm thinking it won't hurt to give those a try? I had to use heat to get the fill plug/bolt to break free. I can't put that much heat on the DEM module...

    Now as far as taking the whole Haldex unit out of the car, I dunno if I'm ready to attempt that. I've heard people talking about the trouble they have trying to decouple that drive shaft/CV joint from the front of the Haldex. I'll have to decide how badly I want AWD. I really loved the way the 2002 handled in the snow.
    2007 XC70, 206,000 miles
    2002 V70XC, 130,000 miles, parts car

  9. #9
    Join Date
    Feb 2013
    Location
    Boston, MA
    Posts
    1,196

    Default

    Quote Originally Posted by Xfingers View Post
    Thanks for the info, vtl. So after you drilled a slot in the bolt head, the flat screwdriver allowed you to deliver enough torque to break the bolt free. Geez, I would think a 4mm allen key would give enough bite to turn that bolt. I guess you guys are saying the allen key slips and strips out the head. The part is out for delivery so I'll probly give it a go next week. I've got Deep Creep, PBBlaster, Acetone + ATF. I'm thinking it won't hurt to give those a try? I had to use heat to get the fill plug/bolt to break free. I can't put that much heat on the DEM module...

    Now as far as taking the whole Haldex unit out of the car, I dunno if I'm ready to attempt that. I've heard people talking about the trouble they have trying to decouple that drive shaft/CV joint from the front of the Haldex. I'll have to decide how badly I want AWD. I really loved the way the 2002 handled in the snow.
    I was able to extract only one bolt. The other one was badly welded, I had to take Haldex out and drill the slot on Haldex along the bolt.

    Penetration fluids won't work I think. It's not rust that holds the bolt inside, it's a steel-aluminum diffusion bond. Also too much of PB Blaster used may ruin weak DEM seals completely and you'll be looking at DEM disassembly to clean it up and reseal.

    CV joint removal is not that bad actually, just prepare couple of bolts (I forgot the size, M8?), the flange has threaded holes on the back, which you can use to push CV joint out. Then you need an impact wrench and 24 mm (?) socket to undo the big flange bolt. The socket needs to be cut a bit, because the bolt is low profile, standard socket does not have enough grip. Without flange you'll have access to 4 M10 bolts, and that is it. All AOC fluid will leak out, btw.

    FWD Volvo still pulls good. However, when AWD becomes FWD due to Haldex failure, engine computer does not realize it and tries to push the car with all the might: sleeping front wheels, bad torque steer, etc.
    2002 V70 (sold)
    2005 XC70 (Telos Road took it. Did a chassis swap)
    2016 XC60 (sold, P.O.S.)

  10. #10
    Join Date
    Jun 2013
    Location
    Northeast
    Posts
    584

    Default

    Thanks again, vtl. It won't surprise me if the bolts turn out to be welded/fused/bonded to the DEM. I can't quite picture "drill the slot on Haldex along the bolt." Maybe if I'm looking at the DEM it'll make more sense. Did this require repair to the DEM after the bolt was removed or were you able to just thread a new bolt and you were good to go? I guess I'll burn this bridge when I get to it.

    This car ain't a DD so I can keep it in the driveway during the heavy snowstorms!
    2007 XC70, 206,000 miles
    2002 V70XC, 130,000 miles, parts car

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