Doing Hurricane Michael cleanup here and found I needed to do some repair work on my aging McCulloch chainsaw – and that required the use of a flange sealant. It just so happened that I have a half-full tube of Loctite 573 left over from my Jaguar-owning days, and it actually appeared to still be good.
First attempt failed, though – the saw was incontinent, leaking bar oil. That, in turn, led me to do some internet research to see if Loctite 573 goes bad on the shelf. Didn’t find any age warnings, but I did learn that 573 is Loctite’s slow-cure product, intended for applications that may take a while to fully assemble. A chainsaw is decidedly not that, it can be torn to bits and fully reassembled in an hour or two. Loctite 573 also, oddly enough, takes longer to cure when used between aluminum flanges than steel, requiring only 24 hours in steel applications but 72 hours when used on aluminum. It didn’t really say any of that on the tube, but it makes sense that such a sealant requires some time to cure.
It also turns out that it takes longer to cure if the parts don’t fit together as well as you might hope. The cure time is a function of the joint gap, with tight-fitting joints curing more quickly than joints that end up with a few thou of gap. Fortunately, the flanges on the bar oil tank on the chainsaw fit very tightly indeed.
So I let it sit for 72 hours the second attempt, and now it doesn’t leak.
I think Loctite 518 is a fast-curing product, but even so, it probably wouldn’t be wise to just slap the engine together and try to start it immediately, especially if you’re a mech that works fast.