Lock Nut Question

[LCOX]

I've posted a picture of a lock nut with the plastic insert in it.
-Can these nuts be used more than one time?
-Or will they loosen up over time if tightened/torqued down more than once?

[73pcar]

I consider them a consumable...I replace mine with new ones...BelMetric (a metric hardware supplier in Massachuesetts) is your friend.

[dannobee]

Even the FAA says that you can reuse nylocks as long as they still have some holding power.

That said, it's common to replace on reassembly.

[Snitzler]

I reuse once and put in an order for next time. +1 for Belmetric.

[pmax]

Host sells them too.

https://www.pelicanparts.com/More_Info/PELWR036808.htm?pn=PEL-WR-03680-8

Nice and pretty.

[Walt Fricke]

This is a sort of your choice issue. I just reuse them. I haven't bought a valve cover gasket and hardware kit in 25 years, I think. Gaskets, yes (though I like the red rubbery ones, which you can reuse as long as you don't try to take them off hot, as they can tear). I've yet to have one of these back off.

I do suspect that the nylon insert plays a role in keeping oil from migrating up through the threads and moistening the tip of the stud. But I can't say that is a proven fact.

Of course, these are not expensive, and brighten up a rebuild.

Ordinarily, when proper torque is used to clamp a bolted joint, the fasteners won't back off. Rod bolts are a good example, or head bolts.

The valve covers are a sort of special case. Back when, the gaskets were cork. It compresses, and I suspect compresses even more over time, so the nuts are going to lose torque, so to speak. And aren't applied with the torque used, say, on the case perimeter studs. Typical gaskets are harder these days, but the reduced torque means more potential for a nut to back off.