Exhaust studs, bolts, nuts: locktite or anti-seize?

[westslope]

A neighbour rides a Harley and says he puts blue locktite on all his bolts due to the vibration. He recommended I do the same for the off-road Xterra. He has worked as a hunting and fishing guide in remote parts of British Columbia so he knows what hard pounding washboard looks and feels like.

I have never seen off-roaders recommending locktite for anything. Anti-seize? Yes. Torque to spec? Yes.

My intuition is that the advice is bad but I thought I would put it out there. I am inclined to stick to anti-seize, high temperature aluminum in the case of the exhaust system.

Is there any merit to adding locktite to stud/bolt/nut connections on the exhaust system? Thoughts?

 

[TerryD]

The heat defeats the blue loctite. I use antiseize.

 

[meisanerd]

Id be guessing a Harley vibrates a whole lot more than an Xterra anyway due to differences in vehicle size, there is a whole lot more weight to have to throw around in an X to get that sort of vibrations, and anywhere you do, they would be a lot less pronounced. And we have much larger suspension to absorbe road imperfections.

 

[westslope]

Any thoughts on using washers and/or lock washers on exhaust connections?

I would think that lock washers would not work in the high temperatures.

 

[TerryD]

I use flanged nuts. No issues.

 

[Prime]

Flange lock nuts or metal locks.

 

[westslope]

Flange lock nuts or metal locks.

By metal locks, exactly what do you mean?

 

[TerryD]

The top thread is crushed and causes it to lock vs a ny-lock nut with the plastic crimped in the top of the nut that the exhaust heat will melt out.

 

[westslope]

Looks like the brake and muffler shop that the Nissan dealership contracted the catalytic converter/exhaust system work to used Red Locktite on the bolts. I removed the bolt it the picture below from the rear of the driver side primary cat because it had no nut. Replaced with a new bolt, a flanged nut, applied aluminum anti-seize and then torqued to spec 39 ft-lb.




Am in the middle of removing a similar nutless bolt on the passenger side primary catalytic converter and it feels like I am about to break the bolt. Heat and PB Blaster! are unlikely to work and I will have the chore of extracting the broken bolt. UPDATE: Went at 'er with a propone torch again. And managed to get the bolt out! I'm such a worry wart.... New bolt and flange nut went on and were torqued to spec 39 ft-lb.

This all stems from a regional dealership offering to replace the cats with aftermarket Eastern cats in late 2021. (I asked around because the best muffler/exhaust shop in this town of 100K souls had shut down for good at the beginning of the pandemic.) The dealership had difficulty with the fit so they, without asking, contracted out the job out to a local hole-in-the-wall Brake and Muffler shop. Worked over 2022. In 2023, I have had P0430 DTCs codes 3 times, every time I go off road or do a rough washboard dirt road. Lesson learned. Either do it yourself or get a competent shop that specializes in exhaust systems to install aftermarket components.


P.S. @Prime, @TerryD: Thanks! I know all about metal lock nuts now.