Another post - sorry - Aluminium corriosion

Discussion in 'CI Motorhomes' started by redpis, Jun 1, 2010.

  1. redpis

    redpis Read Only Funster

    Joined:
    Mar 8, 2009
    Messages:
    24
    Likes Received:
    0
    Hi,

    Last week whilst drilling the back of my Carioca 656 a brown fibrous mushey goo cam out, oh dear!! rotten wood.

    The upshot was a complete strip out of the bed, ply wall, insulation and the replacement of 4 cross members and splicing in 4 peices of damaged timber.

    The source of the mositure ingress was the high level brake light.

    Whilst undertaking this work, inspecting the aluminium skin clear evidence showed a white powedery oxidisation had corroded through in several places, cleaned the area and filled and sprayed, so all is well, however, what elements would have caused this? is it possible that the damp wood caused some form of reaction with aluminium?

    Whats your thoughts?

    Cheers

    Ian

    ps if anyone need infor on what I did to repair, just mail.
     
  2. Geo

    Geo Trader - Funster

    Joined:
    Jul 29, 2007
    Messages:
    9,498
    Likes Received:
    5,552
    Location:
    Mansfield,Notts
    Oxygen/Water and Aluminium :thumb:
    Clean up and seal/paint just as you have done, is all you can do
    Geo
     
  3. dave newell lvs

    dave newell lvs Trader-Vehicle Services

    Joined:
    Oct 31, 2008
    Messages:
    2,509
    Likes Received:
    3,309
    Location:
    Telford, Shropshire
    When wood rots it gives out chemicals that eat aluminium so when moisture gets into a motorhome structure and the frame members rot it doesn't take long before there are pinholes in the ali skin.

    D.
     
  4. 4b2

    4b2 Read Only Funster

    Joined:
    May 1, 2010
    Messages:
    14
    Likes Received:
    0
    Location:
    Scotland
    Hi redpis, we also have a 656 and are concened at what you found. What year is your van?

    bev
     
  5. redpis

    redpis Read Only Funster

    Joined:
    Mar 8, 2009
    Messages:
    24
    Likes Received:
    0
    Hi Bev

    The van was registered in 2004, the tell tale signs (hindsight is such a wounderful thing):

    1) Slight rippling of internal wall
    2) Outer aluminium skin had very small patches of bubbling but in a line ( thought it was where the previous owner had fitted screws that were too long, but covered so I could not check, turned out to be the line where the supporting baton was)
    3) Rusting of the high level light terminals.

    Fingers crossed for you

    Ian
     
  6. vwalan

    vwalan Funster

    Joined:
    Sep 23, 2008
    Messages:
    7,594
    Likes Received:
    3,853
    Location:
    roche cornwall
    thats the problem with poor british built vans .germany use aluminium frames .bit like our old english caravans they did the same .we never learn thats why so many go to the wall.
    also sometimes aluminium is better left just to oxodise .not put paint on as this traps moisture and sweats. think of aluminium boats always best not painted. if you do use a good etch primer.
    mind you its also why eriba ,hymer etc cost more to begin with.
     
  7. 4b2

    4b2 Read Only Funster

    Joined:
    May 1, 2010
    Messages:
    14
    Likes Received:
    0
    Location:
    Scotland
    The Carioca 656 is not a "poor British-built van", its Italian :Doh:
     
  8. vwalan

    vwalan Funster

    Joined:
    Sep 23, 2008
    Messages:
    7,594
    Likes Received:
    3,853
    Location:
    roche cornwall
    sorry !i didnt realise .i,ll try to shut up. anyway is it built on a poorly built fiat. ha ha .
     
  9. American Dream

    American Dream Read Only Funster

    Joined:
    Aug 20, 2007
    Messages:
    6,489
    Likes Received:
    154
    Location:
    Lincoln
    Did exactly that with my car when I first bought it.....Got all the surface corrosion/powdering off.Then spent ages cleaning them....

    A coat of etch primer and then the top coats,

    Still on there after 30 years so that says something....

    Mind you it doesn't come out in the rain......:Laughing:
     
  10. reeventu

    reeventu Read Only Funster

    Joined:
    Jan 19, 2010
    Messages:
    15
    Likes Received:
    0
    What a stupid comment !
     
  11. vwalan

    vwalan Funster

    Joined:
    Sep 23, 2008
    Messages:
    7,594
    Likes Received:
    3,853
    Location:
    roche cornwall
    cant be that stupid i didnt buy it. i did put a laugh after wards nothing wrong with a bit of fun. world would be much nicer if friendly barter was compulsory.
     
  12. ArenqueRojo

    ArenqueRojo Read Only Funster

    Joined:
    Nov 10, 2008
    Messages:
    261
    Likes Received:
    1
    Location:
    Anywhere in Europe, so fa
    I am not sure that the rotten wood reacting with the aluminium will be the problem as the ali needs to have corroded to let the water in in the first place!
    Think this is the problem we always had with the old Land Rovers: ali sheets fixed with steel screws. The ali reacts with the steel setting up electrolysis like a battery. If the manufacturers invested a few pence into fibre or plastic washers the old Land Rovers would last three times as long. So that wouldn't be good for profits!!!
    Patrick
     
  13. vwalan

    vwalan Funster

    Joined:
    Sep 23, 2008
    Messages:
    7,594
    Likes Received:
    3,853
    Location:
    roche cornwall
    with the problem on old caravans doing just the same it always amazes me its still the way some builders build their vans. dont they ever learn or dont they care?
    bedford buses had this typeof structure as well . hymer etc know how to do it. and its reflected in the resale prices.
     
  14. dave newell lvs

    dave newell lvs Trader-Vehicle Services

    Joined:
    Oct 31, 2008
    Messages:
    2,509
    Likes Received:
    3,309
    Location:
    Telford, Shropshire
    Frequently the process goes something like this:

    Walls made of sandwich construction using a timber frame and ali skin.
    Roof made of sandwich construction using a timber frame and ali skin.
    Roof and walls joined together with plated steel screws through ali skin into timber frame.
    Ali finishing trim fitted over joint with non setting mastic between but fixed with plated screws through ali trim and skin into timber frame.
    Plastic finisher fitted to hide fixing screws.

    Problem is that in the process of fitting the fixing screws the plating gets damaged, this allows moisture and oxygen to attack the steel screws which then rust away leaving a perfect funnel right into the heart of the upper framework members. This moisture then wicks along the timbers and wet rot sets in.
    Wet rot in wood gives off chemicals that will eat ali leaving you with a line of perforations showing where the timber members are.

    I know this because I had to rebuild a quarter of the framework of my last motorhome (1990 Autohomes Highwayman) and completely reskin the coachbuilt body!

    D.
     
  15. American Dream

    American Dream Read Only Funster

    Joined:
    Aug 20, 2007
    Messages:
    6,489
    Likes Received:
    154
    Location:
    Lincoln
    You are so right....

    There's no learning curve or maybe....He says cynically...They realised that the shorter time they lasted the better because then the owner MIGHT just be in the market for buying a new one.....

    !!!!!!:RollEyes:
     
  16. vwalan

    vwalan Funster

    Joined:
    Sep 23, 2008
    Messages:
    7,594
    Likes Received:
    3,853
    Location:
    roche cornwall
    or do we blame the customer they keep buying them. look at a eriba even when they are really old the frame is still strong .i think its time for the end user to ask the questions and use their money wisely.i imagine the view is it sells keep doing it.
     
  17. American Dream

    American Dream Read Only Funster

    Joined:
    Aug 20, 2007
    Messages:
    6,489
    Likes Received:
    154
    Location:
    Lincoln
    Let's face it.....

    There are so many sales scams and tricks nowadays....(My Pet topic) Over-packaging and making things appear better and bigger than they actually are....

    Just take the chocolates out of the box and measure the "wasted" space you are paying for...

    I have a 37 year car....No Body Rot

    Delorean built their's ....out of Stainless steel...

    In this Throw-Away society today it makes perfect Sellers sense to build to last for a Finite amount of time....

    They could build to last for much longer but where's the sense in that???

    Sales would tumble...

    :RollEyes:
     
  18. vwalan

    vwalan Funster

    Joined:
    Sep 23, 2008
    Messages:
    7,594
    Likes Received:
    3,853
    Location:
    roche cornwall
    but will anybody that as read this go out and buy one ?i think they will and thats that. i wouldnt buy a wood framed camper . i think i would rather build my own in steel than buy a wooden one. lots of sealer and gooo in between will last alot longer than wood.
    they do good ones in oz and take them really wild places . dragged behind 4x4,s
    thats the sort i like .
    cheers alan.
     
  19. American Dream

    American Dream Read Only Funster

    Joined:
    Aug 20, 2007
    Messages:
    6,489
    Likes Received:
    154
    Location:
    Lincoln
    Hi Alan.

    Doesn't steel suffer even worse from rust/corrosion?

    Also very heavy...I favour Carbon Fibre or Glass Fibre composite manufacture....

    Plenty strong enough if constructed correctly....no corrosion......light......easily formed into any shape......waterproof.....Again if constructed properly......Easily repaired......Colour of your choice......:Cool:

    I am amazed....after being personally involved a few years ago in an accident in a grp car....just how strong it is......

    Just needs fire retardant properties in the resin.

    Went on a course at LOTUS once...and manufacturing techniques have moved on even since then...

    Carbon fibre is the in thing now....Need a big "oven" for a motorhome though...

    http://www.truckcampermagazine.com/tcm-exclusive:-2009-hallmark-k2/

    Steve.
     
  20. vwalan

    vwalan Funster

    Joined:
    Sep 23, 2008
    Messages:
    7,594
    Likes Received:
    3,853
    Location:
    roche cornwall
    if you use factory painted steel its ok . think they dip it when its hot or something.only grind where you weld then cold gavanise it .use galvafroid or one of the marine makes .its ok . you could use aluminium its available. i just noticed that alot of the ozzy adventure trailer had steel construction and it seems to be ok. they build there 5ers with it as well/ might not be light weight but built to last .
    i,m lucky other than the roof and the axle boogies all mine is aluminium even the chassis and floor . onlt 23 yrs old and is always ready for the next adventure.
     

Share This Page