....yeah, this isn't really a Slick-specific deal, but I know you guys will be able to provide an answer to my question:

It is fairly well known that when fastening dis-similar metals together, some sort of a lubricate/thread coating should be used to prevent/reduce the corrosion between the two metals.

So let's say I am torquing down a set of steel headers to an aluminum cylinder head with an exhaust header gasket in between. The earlier rule-of-thumb tells me I should use a thread locker, such as blue loctite, on the steel bolts to secure the header to the aluminum cylinder head, and the bolts should be tightened in the normal torque sequence to ensure the header bolts down squarely.

Because of the heating and cooling that goes on at the header-cylinder head junction and that there may be some compression/shrinkage of the gasket, many header manufacturers recommend that the attaching bolts be re-torqued after at least one heating/cooling cycle.

a) If I go back and re-torque the attaching bolts, wouldn't the thread locker give me a false torque reading?

b) Will the thread locker material 'burn out' over time and become loose?

What about in the situation of an aluminum intake manifold... where some steel attaching bolts may go into the coolant jacket, so the bolts must have some sort of thread sealer as well as die-electric thread coating:
c) Is the thread locker/sealer sealing ability messed up when the manifold bolt torque is rechecked?

d) What do you guys do in these examples?

Thanks in Advance, Guys!
BarnieTrk

 

Companies like Loctite offer many grades of thread adhesives with different elasticity and temperature characteristics. Having said that, I would only use an anti-seize compound on headers and go through the re-torque sequence as you described. As far as your intake manifold goes, any re-torque with thread adhesives applied, will break the adhesive if fully cured. Most all adhesives set in the absence of air and are also accelerated by the application of elevated temperatures. I would personally either not use the adhesive and re-torque or vice-versa. I always re-torque head and intake bolts after a rebuild.

 

Any anti-seize or thread locking compound added to threaded fasteners will alter the torque application. I would have to dig to find it, but I did read this on a tech site some time ago. If torque readings are important, it was advised the threads be bare. If you're just torquing by feel, well, do as you wish.

 

Well,

Since no slick owner usually worries about such things, thought you might be interested in the torque wrench I use for the bolts on my ol' 1966 F100 when I really need an accurate reading within 50 ft/lbs one way or the other and pliers just won't do!

<a href="http://s117.photobucket.com/albums/o67/OldHarley/?action=view&current=tork-grip.jpg" target="_blank"><img src="http://i117.photobucket.com/albums/o67/OldHarley/tork-grip.jpg" border="0" alt="Photobucket"></a>

 

RaleighDad66,
Of course, I don't know why I couldn't see that before........ DOH!


ddavidv,
You are correct on different torque requirements if dry threads or with lube. I do recall different friction factors for motor oil, grease, etc. I have attached what seems to be a pretty good article explaining bolt torquing and a handy online calculator for torquing different size bolts of differing grades:

ROCKCRAWLER.com - Fastener Tech - Calculating Torque Specs

It looks like a close rule-of-thumb for torque values charts list bolt torque with DRY threads. For a LUBED thread, use ~45% of the dry torque value.


OldHarley,
I will have to admit - I've never seen a wrench quite like that one!

Thanks to everyone who took the time to point me in the right direction - again!
BarnieTrk