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Thread: DEM bolt broke off

  1. #1
    Join Date
    Nov 2017
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    MT
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    12

    Default DEM bolt broke off

    I removed my DEM to get the part numbers off it so I could order a used one. The DEM is not communicating with Vida Dice so I am figuring it is bad (yes all fuses and wiring have been checked). While doing that the top allen bolt broke off leaving just a few threads above. I tried to JB Weld a nut on the end to get it out and that failed.. I practiced welding a 8mm nut on a bolt and decided that would be way to risky as I might destroy the mating surface. I can not drill into it because there is not enough room to get the drill bit in straight.. I took a dremel - cut a slit down the middle to try and get a flat head screw driver bit with a wrench ratchet on it. That didn't work and one of the sides broke off! Then I lowered the diff down so I could drill into it. I drilled a hole slightly smaller then a torx bit and then lightly hammered the torx bit in.. Well the torx bit broke off when trying to turn it, and now my drill bits can not drill through the torx bit!! So other then getting some drill bits that drill through hardened steel I don't know what else to do.

    DEMboltSnapped by RockOcean.com, on Flickr

    I am thinking I might just take off the prop shaft, drain the haldex fluid out, and just install the DEM with only one bolt. Is it ok not to have haldex fluid as long as the prop shaft is removed? That way I can drive the car until I have time to remove the rear diff and finally get the bolt out. I found a DEM for $100 so I guess that is something to be happy about. Hopefully everyone can learn from all the stupid mistakes I made trying to fix this all because one of two bolts on what should have been a 5 minute job broke. Thanks for any advice you can provide.

  2. #2
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    Dec 2010
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    Default

    My resource to free a seized bolt that refuses to come out is heat, but not a Oxy/Act, torch as that tends to incinerate items in tight confines, my go to would be a TIG welding torch, precise, localized intense heat usually will convince the most stubborn bolt to turn out easy, but your attempts could have reduced the remainder of the bolt, might not be enough left to get on it, a TIG weld torch will soften the broken torx bit and free the bolt, then allow it to be drilled and a correct sized EZout applied to remove it. Tungsten, Inert Gas welding outfits are not part of most peoples garage equipment unfortunately.
    Last edited by AKAMick; 05-03-2019 at 08:27 PM.
    Current fleet, Countless P.O.S's, Rust buckets, Junk cars, Stolen and other assorted rubbish Volvo cars,

  3. #3
    Join Date
    Jun 2013
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    Northeast
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    475

    Default

    I think VTL may have had this problem, thinking back to one of his posts. I had to replace a failed temp/pressure sensor on my Haldex. I had a mother of a time removing the fill bolt for the Haldex oil. Light heat from a propane torch finally worked but as Mick states, there's lots of wiring around there that can get melted. I tried placing some scraps of metal as "heat shields" but the plastic coating around the wires still got a little soft.

    Luckily, the allen bolts didn't give me any trouble.

    Sorry, I can't advise you on whether you can drive without the haldex oil if the prop shaft is removed. Obviously, you wouldn't want the haldex pump to operate with no oil. If you have no communication with the DEM would it be impossible for the pump to turn on? If you're planning to replace the DEM, does it matter if it gets damaged? What was the specific DEM code(s) being stored in VIDA? One code is usually for the pump, another is for the temp/press sensor.

    Also, $100 for a DEM is less than I paid for a new temp sensor ($135?).
    2007 XC70, 206,000 miles
    2002 V70XC, 130,000 miles, parts car

  4. #4
    Join Date
    Dec 2009
    Location
    GA
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    1,181

    Default

    Quote Originally Posted by RockOcean View Post
    I removed my DEM to get the part numbers off it so I could order a used one. The DEM is not communicating with Vida Dice so I am figuring it is bad (yes all fuses and wiring have been checked).
    Lets back up a minute before your get even more frustrated when your "used" part does not work either.

    Have you followed a known diagnostic process other than guess and replace after making sure the fuse and wiring are not bad?

    Such as the ones provided here https://xemodex.com/us/diagnostic-flow-charts/

    A common problem with the DEM is it gets fried when the pump seizes - so - thinking ahead - you put on a "used" DEM (which will probably not work until it is cloned to your VIN, by the way) - after spending multiple hours and dollars extracting the broken bolt - then the "used" DEM" still does not communicate and immediately fries because the pump is seized.

    Browse what Xemodex offers (they are not overpriced) - AWD/haldex repairs can be very expensive

  5. #5
    Join Date
    Nov 2017
    Location
    MT
    Posts
    12

    Default

    Quote Originally Posted by hoonk View Post
    Lets back up a minute before your get even more frustrated when your "used" part does not work either.

    Have you followed a known diagnostic process other than guess and replace after making sure the fuse and wiring are not bad?

    Such as the ones provided here https://xemodex.com/us/diagnostic-flow-charts/

    A common problem with the DEM is it gets fried when the pump seizes - so - thinking ahead - you put on a "used" DEM (which will probably not work until it is cloned to your VIN, by the way) - after spending multiple hours and dollars extracting the broken bolt - then the "used" DEM" still does not communicate and immediately fries because the pump is seized.

    Browse what Xemodex offers (they are not overpriced) - AWD/haldex repairs can be very expensive
    Yes I have talked to xemodex, gone thru their flow chart twice. I have taken the pump out and tested it, changed the filter & haldex fluid, and changed the diff oil.

    I have heard of DEM swapping that sometimes works without having to have it cloned.. Every single number on my DEM matches up with the one that I purchased. So I think if there is any possibility of it not needing to be cloned I couldn't get a better match.

  6. #6
    Join Date
    Nov 2017
    Location
    MT
    Posts
    12

    Default

    Quote Originally Posted by AKAMick View Post
    My resource to free a seized bolt that refuses to come out is heat, but not a Oxy/Act, torch as that tends to incinerate items in tight confines, my go to would be a TIG welding torch, precise, localized intense heat usually will convince the most stubborn bolt to turn out easy, but your attempts could have reduced the remainder of the bolt, might not be enough left to get on it, a TIG weld torch will soften the broken torx bit and free the bolt, then allow it to be drilled and a correct sized EZout applied to remove it. Tungsten, Inert Gas welding outfits are not part of most peoples garage equipment unfortunately.
    Yes I have definitely gone way pasted that point now :~ ) But thank you for that great info. I am just going to take the prop shaft out for the summer, and bolt my broken DEM on with just the one bolt.. Maybe put a little c clamp where the top bolt should be.. I'm looking to get an oldf 4x4 truck for the winters up here in Montana. When I get a truck I will pull the rear diff on the XC70 and get her all fixed up before winter.
    Last edited by RockOcean; 05-04-2019 at 11:29 AM.

  7. #7
    Join Date
    Nov 2017
    Location
    MT
    Posts
    12

    Default

    Quote Originally Posted by Xfingers View Post
    I think VTL may have had this problem, thinking back to one of his posts. I had to replace a failed temp/pressure sensor on my Haldex. I had a mother of a time removing the fill bolt for the Haldex oil. Light heat from a propane torch finally worked but as Mick states, there's lots of wiring around there that can get melted. I tried placing some scraps of metal as "heat shields" but the plastic coating around the wires still got a little soft.

    Luckily, the allen bolts didn't give me any trouble.

    Sorry, I can't advise you on whether you can drive without the haldex oil if the prop shaft is removed. Obviously, you wouldn't want the haldex pump to operate with no oil. If you have no communication with the DEM would it be impossible for the pump to turn on? If you're planning to replace the DEM, does it matter if it gets damaged? What was the specific DEM code(s) being stored in VIDA? One code is usually for the pump, another is for the temp/press sensor.

    Also, $100 for a DEM is less than I paid for a new temp sensor ($135?).
    I do not have any DEM codes. I had CEM-1A64 and BCM-0094 codes. But after replacing the rear wheel bearing I now only have the CEM-1A64 code. The wheel bearing was good but the magnet ring inside it was crumbling apart.

    Yeah soon as I saw the DEM for that price, warranty, and with all the matching numbers I jumped right on it.

  8. #8
    Join Date
    Jun 2013
    Location
    Northeast
    Posts
    475

    Default

    When you re-install the replacement DEM make sure you put that "washer thingy" onto the temp sensor correctly. It's easy enough but I managed to overlook it. Had everything back together and then I saw it sitting on the ground!
    2007 XC70, 206,000 miles
    2002 V70XC, 130,000 miles, parts car

  9. #9
    Join Date
    Feb 2013
    Location
    Boston, MA
    Posts
    1,070

    Default

    Cut a slot, frozen bolt will come out.




    I have also fixed a couple of bad DEMs, they allow water or oil to infiltrate to the PCB:





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

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