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to seal or not to seal: thread prep. of fittings

Discussion in 'Truck & Equipment Repair' started by Megunticook, Dec 25, 2007.

  1. Megunticook

    Megunticook Senior Member
    from Maine
    Messages: 190

    I have an older Fisher (1980 era) and the manual says in several places to prep threads on hydraulic hoses and fittings with sealant paste (never teflon tape). That's what I've always done.

    Recently downloaded a fairly recent sheet from Fisher's website that gives specs. for tightening various types of fittings. There's a note in bold warning never to use any type of sealant on threads.

    So this year when I reassembled everything after a thorough cleaning and inspection, I just threaded everything together dry. So far no leaks--except for one hose that just needed a little tightening.

    What do you guys all do? Why did Fisher change their recommendations on thread prep.? I understand the problem with teflon tape bits ending up in the hydraulic fluid and causing problems with the pump. But what would the issue be with teflon paste sealant? Just curious about this.

    Thanks for sharing your practices/knowledge.
  2. Snowpower

    Snowpower Senior Member
    Messages: 636

    The paste ends up being just as gunky and will mess up any flowable system just like tape and in my mind easier.

    I never use paste. Always use tape correctly and safely....and Not Overly applied with no problems and Ive been sealing pump hoses for 25 years.

    Most connections dont need additional sealant, but I always add some unless its a compression fitting. My brain wont let me thread them without taping.

  3. SnoFarmer

    SnoFarmer PlowSite Fanatic
    from N,E. MN
    Messages: 9,883

    Never Use goop on your hydraulics it is worse that tape to get out of your system.

    Goop & tape will clog valves and your filter/s

    I have been preaching just this for years.
    "never to use any type of sealant on threads."

    On an occasion on some older rams a little tape maybe necessary to stop them from leaking as a lot of them used a pipe fitting at the ram.

    The reason for this is that the threads do not make the seal.
    Ether it is a tapered fitting or they are using an o-ring to make the seal.
    Last edited: Dec 26, 2007
  4. Snowpower

    Snowpower Senior Member
    Messages: 636

    Oooooo yeah never use any sealer with o-rings and you dont need to on tapered end fittings but again.....a little bit safely and correctly applied wont hurt.

    Its a hard habit to break when you are used to applying sealer.
  5. B&B

    B&B PlowSite Fanatic
    Messages: 12,777

    Couldn't agree more... using liquid based thread sealant your much more likely to contaminate the system...

    And if your gonna use anything, and ONLY for use on tapered pipe threads, use tape.

    Start the tape out a few thread up from the bottom of the fitting to keep the threads from cutting the tape off the bottom of the threads and entering the system..

    Don't use more than a wrap or two.. more is not better!