Originally Posted by briansansone
I got a splice in cooling system drain. Its an aluminum tube, with a screw in
brass petcock. I assume I have to use something to keep coolant from leaking past the threads. I worry that if I just use traditional thread sealant, when I go to open the petcock , the whole piece may unscrew; especially as it ages and gets beat up. Will thread locker seal it?
Locker will seal it. Removing the petcock risks taking the threads out of the aluminum, so you probably want to use a small valve than a cheap petcock as they do frequently fail. Or install an intermediate fitting so the adapter tube's threads don't take the petcock's installation loads.
Coolant is sneaky stuff it works hard to find away out.
Of late I've taken to using the thicker, oil and fuel resistant yellow Teflon tape thread sealer on bolts and fittings with excellent results.