thread sealer vs. thread locker

[JHZR2]

Hello,

Just curious if anyone can give the 30-sec. rundown of thread selaer vs. locker.

My issue is this - I have a series of bolts that are specced for 89 in-lb of torque for full tightness. They are in an application that gets very hot and then cools to ambient.

My issue is that I need a substance that keeps the bolts in place properly at these high temperatures, but is not so strong that it will be impossible to get these weak, small bolts back out in the future, if needs be.

Threadlocker red just has such a strength above and beyond what the bolts can take, that i worry it might grab too tenaciously.

I found a high-temp thread "sealant" at the auto parts store, which, though not making any real clamims about holding the parts in place like a threadlocker, at least claims it prevents leaks at high temperature, vibration, etc.

So all I want to do is hold weak bolts that are not torqued very highly in place in a high-temp, high-vibration application (they are the bolts that hold the upper oil pan to the block, FYI).

Is hi-temp thread sealant the right stuff for this application, or am I better off using the lower temperature-rated, blue or red threadlocker?

Thanks

 

[JHZR2]

According to 3M:

What is the difference between a threadlocker and a thread sealant?
Again, threadlockers and thread sealants are designed for specific purposes and applications and should not be used interchangeably. A threadlocker adhesive locks and seals the threaded parts with stronger locking/bonding strength. On the other hand, a pipe sealant seals threaded parts tighter to withstand very high pressure but with lower bonding/locking strength.

But given that I want vibration locking but with low-strength (because the bolts are small and weak apparently) and yet high temperature resisitance, is the hi-temp thread sealer best, or just good old threadlocker blue best???

Thanks

 

[Gary Allan]

Due to the low tensile strength of the fasteners, I'd use the sealer. I've used industrial pipe dope, sorta like a pasty mix thing as a pseudo lock-tite. Worked well in a high vibration environment. I'm unsure what number it was ..but Rectorseal was the name. We used it on steam and all kinds of stuff that would meet your temp requirements.

 

[eljefino]

There are various grades of threadlocker, from ultimate to something intended to come loose again.

I find blue stuff on various car parts that I assume is meant to be broken free again.

The only threadlocker I ever bought came in an unexpectedly tiny tube and was made by Permatex, IIRC.

 

[The Critic]

I'd say Loctite Blue.

 

[1sttruck]

I've been using more thread 'sealer' lately and have been happy with the stuff. It's often advertised as being a hi-temp product, more so than the vanilla Loctite red or blue, and seems to also do a decent job on gaskets instead of silicone sealers. Instead of using the expensive, small quantities of white Loctite hi temp thread sealer I've been using plumbers teflon sealer as it seems to have about the same specs, smells the same, is advertised to work on a similar range of chemicals, and seems to set up the same. Sometimes you gotta just be a wild and crazy guy.....

 

[doitmyself]

If these are indeed small, weak bolts and you use a torque wrench, be aware that applying any type of lubricant will change the torque applied. Most sites say you should reduce the torque value by 10 to 30 percent. Are your torque specs for clean, dry threads or for lubricated threads. Just be careful you don't twist them off.

Won't the bolt torque and the compression of the gasket hold them in place?

Also, for you and especially Critic (will drive him zany), here is a list of about FIFTY different types of Loctite brand thread sealants!

http://www.type2.com/library/chemicals/loctite.htm

The 246 (on other sites) is high temp and lists oil pans as one use. I would call the guys at Loctite for an answer.

Have fun.

 

[mechtech2]

High vibration for oil pan bolts?
That should be the most stable part [engine block].
Clean tapped holes are needed. Oil in them will make the sealer/locker ineffective.
I'd use Locktite blue. Does the factory have any recommendations?

 

[BradC]

Originally Posted By: The Critic
I'd say Loctite Blue.

Ditto.

This is what I used on the bolts that attach my sway bar to the torsion bar on my HHR. Loctite Blue and 45 ft-lbs of torque. Holds them in tight until I need to remove them.

 

[alreadygone]

If factory used an add on product, I'd try to get same. If factory left dry, I'd do same.

Bob

 

[1sttruck]

'... gets very hot..'

This suggests that the regular blue/red Loctite may not be the best locker, so checking the operating temp is in order.