Refurbing a 2011 PL41, and there's some leaking around two of the plumbing joints. How essential do you guys find the thread locking glue in this regard?

I would look to finding the cause of the leak and more towards replacing washers, O-rings and gaskets rather than LocTite. Teflon thread seal might be another remedy. Thread seal super glue would be used where vibration might loosen a mechanical joint. I would not use it as a 1st line defence of a plumbing joint.

In my experience thread-lock is the all-around worst solution for sealing leaks. Thread-lock don't have the longevity of some other solutions (it will crack from vibration) while thread-locked parts have the highest chance of breaking on the inevitable disassembly. I always go in this order to seal leaks: copper washer>teflon washer>O-ring(FKM is the best)>teflon tape>klingerite washer>thread-lock.

If you're assembling a joint that needs thread sealant, almost always tapered pipe threads, then using it is required, if not it should never be necessary or used. The choice between Teflon tape and paste sealants is then mostly a matter of choice.

Quite true, since those non-taper threaded fittings seal by either compression rings or mating surfaces (as in flare fittings) and pipe dope or Teflon tape could interfere with proper sealing, except perhaps in the case where a compression or flare fitting is subject to strong vibration and the threads may loosen. In that case a thin coating of thread locking compound might be justified.

I think we need to be clear about this, for the sake of those who are less than fully DIY savvy. I think Steve came the closest . Thread locker is for locking joints. It comes in several formulations, some of which can be forced apart and some which are quasi-permanent. It is to combat vibration or other forces that might loosen a nut, bolt or thread. It is not formulated to seal joints, even though it might work as such. Leaky joints require proper washers, O-rings, Teflon tape or pipe dope, depending on the nature of the thread. I hereby relinquish the apple box podium

And while Nunas is mostly correct, he did neglect that there are joints in espresso machines and elsewhere that require no gaskets, o-rings or any sort of sealing assistance except to be properly aligned before tightening. Those kind require absolute cleanliness before assembly.

Yup!

ira wrote:And while Nunas is mostly correct, he did neglect that there are joints in espresso machines and elsewhere that require no gaskets, o-rings or any sort of sealing assistance except to be properly aligned before tightening. That kind require absolute cleanliness before assembly.

I assume the fittings you refer to are of the type (compression ring and mating surface--e.g."flare") that I mentioned in post #6 above. John Guest and Sharkbite fittings operate on a different principle than compression/flare fittings. My point was that their nuts can loosen under heavy vibration and can leak when they do. That is one situation where a thin coating of thread locker on the threads (not on the sealing surfaces) is useful.

Since I had it completely apart, and I found the official Lelit YouTube channel, as well as the Lelit Insider channel, I let them be my guide. Between those two channels there is enough coverage to show about every single threaded joint, and the technician either directly instructs us to use a thread locker, or you can see him do it, or you can see him clean off the original material.

By the way, in the Anna there are straight threads, and tapered threads. There are multi-material joints. There are joints with flat, and tapered mating surfaces. There are joints that seem to have mating surface, but without sufficient length to actually make contact. It was confusing, to say the least.

Google, and YouTube are your friends. Go slowly, and carefully checking your information before proceeding.

To conclude: My machine is assembled, and making respectable espresso.