Question 1

How much should I apply to the threads on a hydraulic fitting? It says 3/4 of a thread but I don’t know how much that really is...

Accepted Answer

Loctite 592 has a ribbon style nozzle, wide slot for discharge.  The correct method is to hold the end of the nozzle up against the side of the fitting, so the width of the slot opening is across a few threads.  As you squeeze the tube gently and dispense the sealant into the root of the threads, slide the nozzle around the fitting in order to go ¾ of the way around the tube.  Feel free to go 360° around if you wish.  That’s a little excess material but won’t really hurt.  You end up with sealant in the root of the treads only, which is enough.  Hope that helps.

Question 2

Is the "activator" necessary or will the sealant work without it?

Accepted Answer

While the manufacturer recommends cleaning with their cleaner (that just happens to be a primer and activator) I have used the 592 thread sealant and even the 518 gasket maker with other cleaners such as vm&p naphtha (that is not a primer or activator) with excellent results.  A primer is recommended when both surfaces are considered "inactive". The Loctite primer defines what this is.

Question 3

How strong is the thread locker? Can fittings be removed?

Accepted Answer

This is not thread locker.  This is thread sealant (like pipe dope).  You will be able to remove the fittings.

Question 4

I have a brass engine coolant temperature gauge leaking. Do i have to drain the coolant before using and let dry completely?

Accepted Answer

The fitting must be clean and dry prior to applying the 592, and it should be allowed to cure for at least 24 hours (preferably 72) before adding the coolant back into the system.  Any other questions, please reach out to our technical team at 1-800-LOCTITE

LOCTITE 592 Automotive Opaque Thread Sealant - High-Pressure, High-Viscosity, Prevents Galling - 50 ml, 1 Pack

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