strongest thread locker

[artieb]

Hi, I have a situation where stretch head bolts, is starting to crack my blocks bolt hole. The crack is not critical to anything, except clamping the head. I can use ARP studs, and I would like to use a thread locking such as locktite. Any advice would be appreciated, Artie

 

[csp]

The strongest stuff is the kind that requires heat to remove. I think it's the green, but not 100%. Go to loctite's website and have a look.

That said, I wouldn't use loctite on head studs.

 

[artieb]

I see 272 red, heavy duty on loctite website, no green... still looking

 

[kellymc]

Green, requires heat to remove

 

[chris_1001]

Red is the "permanent" thread locker not the green. Heat is how you break the fastener loose.

 

[GCncsuHD]

Green is labeled as "sleeve retainer", that is some STRONG stuff, puts Red to shame. You could put a bolt in with absolutely no threads and it would hold it together. Not to be confused with the penetrating/wicking Green Loctite, it is weaker than the Blue stuff, but is meant to be used after assembly.

 

[The mean fish]

You mean besides beach area rust?

 

[Prototyper]

Yup, Loctite 680 is the strongest **** I've ever played with! Make sure everything is absolutely clean and dry, hit both surfaces with 7649 primer, 680 on the male threads, and you have to be pretty quick getting the parts assembled, as it sets up quick! It takes real heat (like 500F) to even have a prayer of getting stuff apart.

680 has a rated continuous working temp of 300F. There is also a different flavor of retaining compound, 620 which is rated to 450F. I have never used that one.

 

[EdT]

We used to use Lock tite 620 cylindrical retainer for threaded parts that were used at high temp (450F) and, while not its recommended application, it worked very well. It's the green stuff mentioned above. That said, all the lock tite in the world is not going to fix the failure of the block you described. Lock tite keeps stuff from unscrewing, but it is not magic metal glue. You may find it works out OK, but while it's all apart you might want to look into a helicoil or a keensert or something intended to repair threads.

 

[Zeke]

Ryan is the strongest thread locker.

 

[Jswain]

Ryan is the strongest thread locker.

/thread

 

[zkling]

Call loctite and give them the details to see what they recommend. What is the block material?

 

[iajonesy]

We have always used Loctite 609 and it is called permanent for a reason.

Mike

 

[artieb]

The engine block is a pretty high percentage of nickel. I'm confident that the stud would be adequate. There is plenty of cast around the hole, I believe that the locker would help with the stud clamp pressure from trying to push towards and possibly aggravating the split. I'm going for it, 620 or 680 which ever I can find, thanks for all the replies, Artie

 

[Techie1961]

I have often wondered as well when you use studs and Loctite if you should let it set in a floating position or tensioned the way the nut will pull on it. In other words, will the Loctite be stronger if it is uniform on both the front and back of the thread or with metal to metal contact as in tension and the Loctite in the larger gap of the thread face. With the floating method, you will have Loctite completely surrounding the thread on all surfaces.

 

[e-rockin-it]

I have often wondered as well when you use studs and Loctite if you should let it set in a floating position or tensioned the way the nut will pull on it. In other words, will the Loctite be stronger if it is uniform on both the front and back of the thread or with metal to metal contact as in tension and the Loctite in the larger gap of the thread face. With the floating method, you will have Loctite completely surrounding the thread on all surfaces.

I could be wrong but from what I've seen undoing the red permanent threadlocker, it looks like it works by filling the gaps between the threads, so in theory it works best under tension. Since the threads are under tension if you had a gap filler behind the thread it would be harder to undo.

Might be wrong but the red permanent threadlocker looks like that how it works (when I undid it with a torch and large wrench)

 

[t100]

difference between green loctite and red loctite: colors of Dye.

 

[Ingram306]

Small bead of weld

 

[artieb]

What Techie says makes sense, what Ingram says doesn't, in this application. Even with a hole drilled in the ends of the crack.
Seems that if you were to threadlock without tension, when you did apply torque the play in the top of the studs threads would be compromised when the nut lifted the stud to the top of the threads.

 

[EdT]

FWIW, Red 271 Loctite and green 620 Loctite appear to have very different chemistries. The difference is more than the color they are dyed.

 

[gearhead1]

If the block is already cracked, I don't understand how thread locker will prevent the crack from propagating.

 

[Fcvapor05]

It looks like it's too late for me to save this thread, but for anyone who reads this, DO NOT put threadlocker on head bolts of any kind, but especially torque-to-yield bolts.

 

[GCncsuHD]

It looks like it's too late for me to save this thread, but for anyone who reads this, DO NOT put threadlocker on head bolts of any kind, but especially torque-to-yield bolts.

That was already covered in the second post...but this guy seemed pretty set on using it.

 

[csargents1546]

Just a question, did you put oil on the threads before you torqued and stretched them? I have seem issues when tech do not put oil on the threads, creaks and pops like no tomorrow. Might try that on the other bolts that the holes are not cracked.