Fix leaking thread

Jimfromcanmore · Sep 1, 2012

The 90 degree has a slow leak. Given there is fluid in the cylinder, obviously, how does one go about replacing the seal without making a mess or contaminating the fluid in the cylinder when rescrewing the thread assuming old sealant is now in the cylinder side of the thread?

woodlandfarms · Sep 1, 2012

In my opinion these type of connectors are cheap and a pill. Simple solution is take off your hose, take out the L adapter. Put on Pipe thread tape and reseat. The hose does NOT take pipe tape.

IMO, a better method is replacing the L adapter with the type that has a nut that clamps down on the cylinder with a washer and gasket. I know nothing about the names, JJ will chime in and I will learn something new...

Zebrafive · Sep 1, 2012

I think woodlandfarms is refering to SAE / ORB (O Ring Boss) fittings. You can not just change to that if the cylinder has different threads. My guess is you have NPT (National Pipe Threads). Do NOT use tape, use a pipe thread sealant/compound. Leak may be because you did not get fitting tight when you positioned the 90, or it was backed off to position the 90.

J_J · Sep 1, 2012

The fitting into the cyl looks like NPT. Just use pipe dope, and a new fitting. NPT fittings are not designed to be used over and over.

woodlandfarms · Sep 2, 2012

OK guys, clearly my hydraulics shop (as well as my tractor manufacturer) have been giving me bad information....

I have an few SAE/ORB on my tractor. I have had no issues (Hydraulic shop recommended them). When I have removed the NPT connectors, there was tape on the connector so that is what I followed up with. Why is this not correct and why is dope better.

I think this note came of as agressive which it is not intended. Just trying to learn as everyone here has great experience.

lilranch2001 · Sep 2, 2012

woodlandfarms said:
OK guys, clearly my hydraulics shop (as well as my tractor manufacturer) have been giving me bad information....

I have an few SAE/ORB on my tractor. I have had no issues (Hydraulic shop recommended them). When I have removed the NPT connectors, there was tape on the connector so that is what I followed up with. Why is this not correct and why is dope better.

I think this note came of as agressive which it is not intended. Just trying to learn as everyone here has great experience.

If teflon tape chunks break off and gets into the oil, it can jam up control valves and cause more issues than just simple leaks.

NEVER USE TEFLON TAPE ON HYDRO SYSTEMS

J_J · Sep 2, 2012

Carl,

Some people still use the Teflon tape, and some are careful about not putting tape on the first few threads. Even new tractors use it sometimes. More and more people are shying away from it however.

There is also Teflon paste which is least invasive and causes little trouble.

When you unscrew the NPT fitting, is where the problem arises, the Teflon thread is in the threads, and in little pieces. You are supposed to clean all the old Teflon tape out of the fitting and use new tape if that is what you are going to do.

I don't know if this practice of using Teflon tape is written in stone yet, but perhaps it should be.

Jimfromcanmore · Sep 3, 2012

Thanks for all the inputs. The one remaining question how to clean the thread on the cylinder without getting bits of old seal into the cylinder and so contaminating the system?

J_J · Sep 3, 2012

Maybe turn the cyl so the ports are on the bottom and carefully clean the threads, maybe even using a vac to suck the debris out of the threads.

More thread sealant. Loctite® 5452

http://www.henkelna.com/us/content_data/141299_LT5557_5452SSF448695.pdf

Zebrafive · Sep 3, 2012

I agree with what J.J. posted. The main problem with teflon tape is when fittings are removed the shreds left behind can cause problems. If you choose to use teflon tape, do not wrap the first couple of threads and don't use too much.