Cylinder head studs

[sanibel sailor]

Replacing my head gasket. Two of the studs came out with the nut. I know how to reinsert them using two nuts. Do I use Loctite or anything on the stud into the block? Service manual is silent on it. Westerbeke W 30 a.k.a. 4- 91

[rbk]

I’d use high temp (red locktite) not necessarily to hold in place but to prevent seizing.

[roverhi]

The problem with using various forms of LocTite in studs is getting the studs out if it should break the next time take the head or whatever is removed. LocTite does act as sealant to help prevent rust locking the stud in but, especially red, LocTite also adds the difficulty of replacing the stud. I've just double nutted the studs and run them back in if it's similar metals. If it's dissimilar use Never Seize to install.

[Jammer]

Recommendations vary but with head fasteners it is the elasticity of the fastener that will hold it in place; there is no more need for loctite on the threads than there would be on a head bolt (which are typically installed without loctite).


Some mechanics might use blue loctite more as a sealant than anything else. Red loctite poses a removal problem, as noted upthread, as the breakaway torque exceeds the strength of the fastener for bolts the size of typical head bolts.

[jimbunyard]

Typically if the end of the stud goes into the water jacket, some sort of sealant is used.

If not, light oiling is the norm, with the studs firmly seated with double nuts or similar.

Don't forget to clean the threads first.

[rbk]

Blue locktite in high heat will crystallize rather quick and eventfully gum up from thermal cycling. Red will hold longer but will also break down. If you’re removing your cylinder head yearly then dip them in motor oil before installing for easy removal and corrosion inhibitor. No sealant will last in the head for very long and if you remove it in ten years don’t expect it to hold much of anything. I use red on all my high heat connections, it goes soft after a while and acts more like a thick grease that doesn’t burn off. Blue crystallizes and goes hard when cycled and can cause more problems than it’s worth (with high heat applications) also don’t expect blue to hold anything for any length of time in heat applications IMO