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  1. #21
    Join Date
    Jul 2014
    Location
    Sail on the Medway, Kent from Chatham Maritime Marina
    Posts
    1,914

    Default Re: Trying to undo stainless bolts

    I have been told that steel bolts into an alloy engine head can become seized with time. The trick to break the bond is heat from a MIG welder on the bolts. This expands the steel quicker than the alloy and breaks the corrosion that has seized them together. If you have access to a MIG welder, it would be worth trying.
    Last edited by Concerto; 26-08-19 at 20:34. Reason: Extra info for clarity
    If my foresight was as good as my hindsight, I would be a multi-millionaire.

  2. #22
    Join Date
    May 2019
    Location
    The Clyde, Scotland
    Posts
    28

    Default Re: Trying to undo stainless bolts

    On the SS bolts I agree we need more info or pictures to be able to come up with some better suggestions.

    What kind of head are we talking about?

    Plenty of WD-40 etc sprayed before and allowed to soak in then regularly while undoing is the first solution(FPI fluid is the best for this if you can scrounge some)

    Hitting the problem screws/bolts with a hammer can help to shock the seized part free.

    If we are talking countersunk flat screws then a screwdriver with a square shank and a corresponding spanner can help give some more leverage.

    As mentioned heat can work well if you have the kit.

    I prefer a Dremel to gurry out the head rather than drilling as getting a drill started in the centre of a damaged fixing can be a pain. Then once the winch is removed the double nut method to get the stud out should work as once the load is off the threads they are normally easier to remove.

    Although if its a decent sized bolt then easy outs(the left handed drill and left handed fluted bit) work quite well.

    Thats probably the order I'd go in but some more info or pictures would be handy

  3. #23
    Join Date
    Dec 2001
    Location
    Grenoble
    Posts
    31,785

    Default Re: Trying to undo stainless bolts

    Assuming they are machine screws try an impact driver.

  4. #24
    Join Date
    May 2001
    Location
    North Wales, sailing Aegean Sea or Menai Strait
    Posts
    21,978

    Default Re: Trying to undo stainless bolts

    Quote Originally Posted by Resolution View Post
    Vyv
    I have an Edson steering wheel set up , with the compass set in a housing above the wheel spindle. The housing is white powder-coated aluminum (sp USA?) and about six inches high. Several long s/s bolts hold it down to the rest of the steering binnacle, which is also aluminum. These bolts are now very stuck and I really need to lift the housing off to service the steering.
    Is heat the only answer? How best to apply it?
    Or should I just order a complete new assembly?
    Peter
    Plenty of suggestions by others, mainly mechanical. The only chemical method I am aware of is sodium carbonate (washing soda) solution, best done warm. This is mildly alkaline and may dissolve the salts, if it can get to them. No easy answer I fear.
    Answers to some technical queries at new website http://coxeng.co.uk

  5. #25
    Join Date
    Oct 2012
    Location
    Southminster, essex
    Posts
    9,447

    Default Re: Trying to undo stainless bolts

    Do not wast time. Drill it out and re tap to the next size up. You may have to go for non standard (ie not metric) size and thread pattern to avoid going too big. The tip about a left hand drill bit is a good one.
    Last edited by Daydream believer; 27-08-19 at 07:07.
    It is all down to the fact that my wife does not understand me !!

  6. #26
    Join Date
    Jan 2011
    Location
    Gillingham(Dorset) Boat East Cowes
    Posts
    2,692

    Default Re: Trying to undo stainless bolts

    A simple trick that often works is to retighten the screws before undoing

  7. #27
    Join Date
    Jul 2011
    Posts
    463

    Default Re: Trying to undo stainless bolts

    Stainless to stainless thread sometimes “pick up” (described as Galling at beginning of thread)
    Sometimes when this is starting to occur it can feel like the thread feels rough Graunches or notchy
    It can, very rarely be undone by re doing back up or it can seize completely.
    When assembling don’t use copper slip it will make it work.
    We used a molybnium based spray, moly slip or some such.

  8. #28
    Join Date
    Oct 2018
    Location
    A Member State of the European Union
    Posts
    6,600

    Default Re: Trying to undo stainless bolts

    Quote Originally Posted by Rocksteadee View Post
    Stainless to stainless thread sometimes “pick up” (described as Galling at beginning of thread)
    Sometimes when this is starting to occur it can feel like the thread feels rough Graunches or notchy
    It can, very rarely be undone by re doing back up or it can seize completely.
    When assembling don’t use copper slip it will make it work.
    We used a molybnium based spray, moly slip or some such.
    You're right. I've experienced this with the six s/s bolts and nuts holding down my coachroof mounted mast step; all of which had to be sawn off.

    Now I use AG90 https://www.cromwell.co.uk/shop/lubr...bricant/f/8091
    "Brexit: like watching a library being burned down by people who can't read"

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