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stuck piston rings.....what's the secret?

Discussion in 'Chainsaws and Power Equipment' started by Scotty Overkill, Oct 20, 2016.

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  1. Scotty Overkill

    Scotty Overkill Administrator

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    OK guys, before I go and do something rash and stupid, do any,of you have a formula or method for getting piston rings un-stuck? I have this ultra-rare Mac BP-1 here, and I had one HECK of a time getting the piston freed from the cylinder. I finally got it out and got the cylinder honed, but now l'm having problems with the rings. I don't wanna damage the lands, and the rings are stuck with a combo of rust and carbon. Any secrets? Believe me, I'd like to be able to just replace the piston but unless any of you have a cross reference to one I can use, you can't just go to the local Mac store and pick up a piston for this saw....

    I bought a set of NOS rings, but I gotta reuse my piston...

    After a several day soak in ATF/PB Blaster/diesel concoction and over 200 blows with my 10lb slide hammer and custom-made pulling apparatus made from a old pair of vise grips and some saw blade material, it came out. The cylinder is iron-sleeved and in excellent condition, but the rings need replaced....
    20161018_184421.jpg


    After I cleaned the Pistons up a bit. Now once I get the rings out, I'll be off to the races!
    20161018_191625.jpg
     
    Scotty Overkill, Oct 20, 2016
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  2. Grizzly Adam

    Grizzly Adam null

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    Is that an old craftsman c3 drill with one of the new lithium ion batteries?
     
    Grizzly Adam, Oct 20, 2016
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  3. Woodsnwoods

    Woodsnwoods

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    :dex:
    Did you try Kroil? It's expensive, but the best penetrating oil I have used. It is used by the industrial guys on large 1-3 inch bolts on power projects to loosen them up after sitting for years. They were also installed with a hytorq, and have some meat, but they always come loose. I used it last winter on my 3 or snowblower to loosen some salt rusted bolts, and it worked. Good luck :dex:
     
    Woodsnwoods, Oct 20, 2016
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  4. Scotty Overkill

    Scotty Overkill Administrator

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    The drill and battery are around 4 years old
     
    Scotty Overkill, Oct 20, 2016
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  5. Scotty Overkill

    Scotty Overkill Administrator

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    I'm going to buy a can of that Kroil, trying to find it locally.
     
    Scotty Overkill, Oct 20, 2016
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  6. Woodsnwoods

    Woodsnwoods

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    Amazon, its not something you will find locally unless you have a solid industrial supply center
     
    Woodsnwoods, Oct 20, 2016
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  7. Grizzly Adam

    Grizzly Adam null

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    I havebasically the same setup but the drill is probably a dozen years old with batteries a couple years old.
     
    Grizzly Adam, Oct 20, 2016
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  8. Scotty Overkill

    Scotty Overkill Administrator

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    We have a Grainger here, I'll check there first. See the problem with something like these stuck rings is that it's VERY hard to initiate motion, and for stuff like penetrating oil to work, you need to have some way to initiate motion. Very hard to do without screwing up the piston ring lands (grooves). And for the most part, this piston is irreplaceble.
     
    Scotty Overkill, Oct 20, 2016
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  9. OhioStihl

    OhioStihl

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    Electrolysis?
     
    OhioStihl, Oct 20, 2016
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  10. Kevin in Ohio

    Kevin in Ohio

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    In the past, when I have had them stuck, I've had good luck with heating and cooling. Mainly when the piston is aluminum with steel rings. Thermal expansion rates are different so sometimes it is enough to free them up. On stuck bolts the candle wax trick has worked pretty well for me as well because of the same thing.
     
    Kevin in Ohio, Oct 20, 2016
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  11. Warped5

    Warped5

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    So, given that the piston cannot be replaced ..... I'm thinking heating it up with a hair dryer/paint stripper .... let it get to room temp and putting in freezer for an hour .... ??

    Gentle heat/cooling ....
     
    Warped5, Oct 20, 2016
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  12. Bret Hart

    Bret Hart

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    Bret Hart, Oct 20, 2016
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  13. Kevin in Ohio

    Kevin in Ohio

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    I don't think a hair dryer would get it hot enough. I've got an old oven in my shop that I got to do powder coating. Set the parts on a metal tray and bake them, then let cool slowly as you say.
     
    Kevin in Ohio, Oct 20, 2016
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  14. hdtoolmkr765

    hdtoolmkr765

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    Kroil and done!
     
    hdtoolmkr765, Oct 20, 2016
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  15. Scotty Overkill

    Scotty Overkill Administrator

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    Electrolysis is a NO-NO with aluminum, magnesium and pot metal......I was all ready to try it and did some research. This is an aluminum piston with iron rings.

    I read a good thread in a tractor forum that said about using the heat-cool method and, being the rings are sticking out a little from the piston, gently tapping the circumference of the piston ring with a brass hammer, I may try my plastic deadblow hammer or even make a mallet out of a chunk of hickory.

    So I'll get some Kroil, heat and cool it a few times with the propane torch and tap on the ring some. Worst case scenario is I mess up the lands, if I do that maybe I'll look into having them opened up a bit on the lathe and getting slightly thicker rings.
     
    Scotty Overkill, Oct 20, 2016
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  16. cre73

    cre73

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    That is one cool saw. Had to do some google-foo after seeing the two pistons in your hand. Thought you were messing with us or maybe smoked a little to much wacky weed. :loco: :crazy:
     
    cre73, Oct 20, 2016
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  17. hdtoolmkr765

    hdtoolmkr765

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    I've never had to use anything other than Kroil, no heating and cooling, no tapping or anything. I just soak them in Kroil, the next day just pull them off. Done it probably a dozen times. Never had it not work.
     
    hdtoolmkr765, Oct 20, 2016
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  18. bobdog2o02

    bobdog2o02

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    bobdog2o02, Oct 20, 2016
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  19. bocefus78

    bocefus78

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    Yep....and simple green diluted with water is a cheap and easy solution for those ultrasonic cleaners. Crappy description on that one IMO, but some of those machines even heat the solution for you. Heck, maybe all of them do. I dunno?
     
    bocefus78, Oct 20, 2016
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  20. Warped5

    Warped5

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    I got the large one at HF.

    Used to 20% coupon I get in the mail every week ..
     
    Warped5, Oct 20, 2016
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