Pipe dope on hydraulic line connection?

[nbennett]

My neighbors tractor has a hydraulic line leaking at a connection around the threads. the connection is very tight. Can pipe dope or another material be used to seal this? The fluid is UDT.

 

[JDeerekid]

good amount of tephlon tape should do, just make sure you start back a couple treads from the end so to not get any tape in the hydraulic system. Worked for mine. Also there is a special pipe dope out there just for hydraulics, if I remember right it is black or gray color. My local tractor dealer used it on a inline filer setup for my wood splitter and it worked nice. I never did find out what brand it was. hope this helps

 

[nbennett]

Thanks. The reason that I asked is one time I tried Teflon tape on some connections where automatic transmission fluid was used for hydraulic fluid. The teflon tape was quickly dissolved and every connection leaked.

 

[59ih340]

I had the same problem with a large fitting,I used teflon thread sealer from permatex and it's held up fine.

 

[Sherweld]

It's not clear what type of thread we're discussing here

Pipe thread (tapered) is generally the only one where tape or better still, dope would be recommended. Other types of hydraulic fittings seal by other methods. (tapered seats, "O" rings, etc)

 

[TedLaRue]

I think Sherweld is shrewd. I'll elaborate on his/her post a bit.

The fitting could be

1. tapered "iron pipe threads" (IPT)
2. butt joint with a soft copper/aluminum washer
3. "banjo fitting" with soft copper/aluminum washers
4. a joint with an o-ring

For #1, Teflon tape or pipe joint compound might help.

For #2 and #3 above, tightening might help, or you could replace the soft-metal washer. Or if you're desperate, try flipping the washer over. Or you can get a new washer at a NAPA dealer or local car parts dealer.

For #4, the only solution is to replace the o-ring. You could get one at your dealer, but you might find one at a big-box (like Lowe's or Home Depot).

I haven't found it necessary to use tape or dope for any of my hydraulic line joints. But if a previous owner has over-tightened fittings or otherwise distorted them, you could have some problems.


Be aware that over-tightening can distort a fitting and cause it to leak!

 

[ultrarunner]

I use LOCTITE 567 Thread Sealant when needed.

Used in the chemical processing, petroleum refining, pulp/paper, waste treatment, textile, utilities/power generation, marine, automotive, industrial equipment, gas compression and distribution industries. It is also recommended for industrial plant fluid

As with any sealant, paste or tape, care must be used to insure the material doesn't contaminate the hydraulic system.

 

[davey4000]

I had a connection that leaked and I used white teflon tape and later teflon paste. It still leaked. I then used the yellow gas line type teflon tape and it fixed it right up. No leaks. These were npt fittings.

 

[EddieWalker]

I've never come across a hydraulic fitting that required teflon tape or a thread sealer. The preasures on the line are so great that they require a new o-ring or special washer. Most of the ones I've dealt with have all been sealed with O-rings.

Eddie

 

[Sherweld]

I may have the wrong idea here, but the main reason that I use either teflon tape or dope on tapered threads is not so much for sealing, but the ability to take the joint apart in the future if need be. The taper tightness and the micro pores in the thread metals and particularly rust can make many joints a real trick to take apart without damage.

I only say this because I'm old enough to have had to take apart many joints over the years .....

 

[nbennett]

The connection is between a metal line and a quick disconnect(IPT?) on a BX2200. I'm sure that it was previously over tightened. I used teflon tape on Friday and will watch for leaks. I had worked on same fitting before and it did not leak for a couple of weeks. When it started leaking again it was still tight. This all started when my neighbor left to visit her grandkids for a month and left the lawn mowing and tractor in the hands of unknowing family members. I have already spent about 8 hours repairing damage that they caused.

 

[Soundguy]

It's not clear what type of thread we're discussing here

Pipe thread (tapered) is generally the only one where tape or better still, dope would be recommended. Other types of hydraulic fittings seal by other methods. (tapered seats, "O" rings, etc)

Ditto this 100%.. pipe thread where thread deformation make she seal will benefit from dope.. but the orb and taper fit fittings ( JIC, compression, flair.. etc.. ) won't at all..

soundguy

 

[jmfox]

Yep, the dope would only help prevent seizing, not leaking.

jmf

 

[Michaeltymcnamra]

Here is a website that gives solid data on the various types of hydraulic fittings, and explains why some need pipe dope,
and others do not, and instead rely on the o-ring:

https://www.parker.com/literature/Tube Fittings Division/Pipe_Fittings_&_Port_Adapters.pdf

 

[Tractor Seabee]

I use LOCTITE 567 Thread Sealant when needed.

Used in the chemical processing, petroleum refining, pulp/paper, waste treatment, textile, utilities/power generation, marine, automotive, industrial equipment, gas compression and distribution industries. It is also recommended for industrial plant fluid

As with any sealant, paste or tape, care must be used to insure the material doesn't contaminate the hydraulic system.

Do not forget to clean all existing compounds and oil from both male and female threads. Teflon tape is getting a bad rep for contaminating systems with particles. It can play havoc with hydraulic system inerds and almost impossible to get all out. In my pipe-fitting days I had a 10 man crew re-piping three Navy ship 5" gun mounts. Thread sealant was not well specified and the company chose Teflon tape. The sailors started up the systems after we finished and they worked for 15 minutes and quit. Found Teflon particles through out the systems and clogged orifices in all valves. Took three 24 hr days to remove and clean all the piping while the sailors disassembled the system mechanisms and cleaned them. The inspector required us to install a bunch of strainers. Our company lost a bundle on that job and it was an expensive lesson learned. I have never used Teflon tape on sensitive system since. The liquid types work OK as Ultrarunner admonished above.

Ron

 

[CalG]

Obviously, the use by relatives have made conventional sealing methods irrelevant.

I suggest a new tractor with ALL complimentary attachments the only useful solution.

Attitude is everything...................

 

[Texasmark]

I never found a pipe dope locally for 2500 hyd. systems with NPT threads, but have used regular plumbers dope, the blueish gray stuff with the applicator in the lid. Never had a problem.

 

[Gary Fowler]

Pipe dope of any kind is not meant to seal but rather to act as a lubricant so you don't gall the threads when tightening. Proper threads that haven't been overtightened will generally seal with any pipe dope used. One containing copper or/and graphite will work well for hydraulic systems.

Pipe dope will sometimes help seal a bad thread by allowing additional tightening. A turned thread from overtightening usually needs to be replaced to stop it from leaking.

 

[Lineman North Florida]

I have used Teflon tape on hydraulic fittings for years and never had one problem, I must be lucky.

 

[RickB]

I have used Teflon tape on hydraulic fittings for years and never had one problem, I must be lucky.

Or, like myself, you simply understand how and where to use it.