Loctite vs. Anti-sieze - where to use?

I'm in the process of reassembling a 4.0. The FSM does not provide much advise concerning loctite or anti-sieze. Chiltons states to lightly coat bolts with oil unless advised otherwise. Many bolts appear to have had loctite (or something) applied to them during the assembly process.

Can anyone provide critical areas that should receive loctite or anti-sieze during the reassembly process? I know some people would put anti-sieze on anything that loctite is not required on, but what about major bolts like the flywheel bolts (manual tranny)? Would it hurt to use anti-sieze here?

desertred said:

I'm in the process of reassembling a 4.0. The FSM does not provide much advise concerning loctite or anti-sieze. Chiltons states to lightly coat bolts with oil unless advised otherwise. Many bolts appear to have had loctite (or something) applied to them during the assembly process.

Can anyone provide critical areas that should receive loctite or anti-sieze during the reassembly process? I know some people would put anti-sieze on anything that loctite is not required on, but what about major bolts like the flywheel bolts (manual tranny)? Would it hurt to use anti-sieze here?

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I'm one who uses anti-sieze on everything that doesn't get Loctite -- and in some cases I use anti-sieze where the factory might have used Loctite. Loctite is used on bolts/nuts that may loosen due to vibration. I would definitely use Loctite on flywheel bolts, and I believe if you buy them new from a dealer they come with Loctite already on the threads.

Basically, use Loctite if you can't afford to have it loosen under vibration. Use anti-sieze on anything you might have to take apart again. I use anti-sieze on head bolts, except the one that goes into a water passage, which gets black plumbing sealer.

Note that when using anti-sieze you use the torque spec for lubricated threads. Most published torque specs are for "clean dry" threads. With anti-sieze, if you don't have access to a chart or a spec for lubricated threads, reduce the "dry" torque by about 20% to 25%.

I would call an engine builder, some applicaitions want a specific type of loctite, an example of this was the factory front hook kit and the rear skid plate kit, all the bolts came with 'blue' loctite already on them. When I did my weber conversion on our 89YJ the weber instructions said 'red' loctite on the manifold studs but not on the nuts. When my friend was assembling a ford 9" rear the bolts in that gear kit specified 'blue' AND 'red', has something to do with the holding power. In certain applications I use BOTH loctite and anti-seize like those skid bolts, bet your butt I want to get them off at sometime in the future and that makes life easier. I asked a machine shop about it a while ago and they said the two will not interfere with each other.
I have used loctite on main and rod bolts but never on head bolts, I've used anti-seize on manifold bolts and have never had one come loose. Most good engine assembly kits come with instructions on where, when and what grade to use. I think there are like 7 grades of loctite for different applications, the ones you are interested in are 26240, 27100 and 27200, they are rated by temp, torque rating and fastner size. The stuff needs to be put on 24 hours in advance unless you use the curing agent, me, I like to let it dry even though I get impatient to assemble whatever new toy I just got... Oh and you don't have to slather the stuff one, like brylcream 'a little dab will do ya'...god I feel old..