Lock Tight?

[Wheels-a-turnin]

Should I use Lock Tight when bolting together internals like main caps and rod caps?

 

[groundPork]

Should I use Lock Tight when bolting together internals like main caps and rod caps?

Hell NO!!!! ONly thing I ever use it for is maybe the oil squirter threads, Oil pump face plate screws, flywheel bolts.. And that's not even all the time.

 

[Wheels-a-turnin]

How come? It seems like it would be a wise thing to do. Im not trying to be an ass, this is my first engine build and I want to make sure I do things right.

 

[Tom N]

How come? It seems like it would be a wise thing to do.

Then do it.

 

[FORMONTOYA]

I've never used it for internal components, as stated just flywheel, intake/exhaust mani bolts and the like, but now that I'm thinking about it....

With the heat inside the engine the Loctite might start to ooze and then get mixed with the oil and find it's way into the small oil passages, then gum up and really cause some serious problems.

If you go to the Loctite website you'll see that the only "series" they have that is applicable to anything internal to an engine is the 242 and 243 series which can be used for rocker arm studs and adjustment nuts. Even with that I still wouldn't use it on engine internals. Torqued to spec works great.

Someone with more experience should chime in.

 

[Wheels-a-turnin]

With the heat inside the engine the Loctite might start to ooze and then get mixed with the oil and find it's way into the small oil passages, then gum up and really cause some serious problems.
Someone with more experience should chime in.

This makes sense, and I called a buddy that works on engines for a living and he asked their engine builders and they also said not to.

 

[daren_p]

No don't use it on internals, keep the loctite for things such as flywheels, clutch pressure plates, motor mounts, etc.

 

[OverboostXS]

Heat wont eat away at the red loctite.. Some people put a little on their head studs but I wouldn't recommend it.

 

[JamiesTSI]

"IF" you put the red lock tight on the head studs only apply to the threads that go into the block and you must immediately install the head before the lock tight sets up.

 

[dnhieu]

this has nothing to do with using loctite with engine internals but im gonna say it anyways.

also use loctite on transmission bolts. i had them back out on me once and my transmission was litterally comming off my block between shifts. while i did fix it before anything major happened it was definetly a scary moment...

 

[toybreaker]

The torque charts you use assembling an engine's internals are all predicated on the threads being clean and coated with engine oil.

The installed tension from the same rotational torque will change significantly if you use loc-tite, as it has a different lubricity.

Since this is your first motor build, a word or two about what we're trying to do when we torque engine hardware may be helpfull here.

The goal is to provide sufficient tension/clamping force to keep jointed parts from moving relative to each other. This is done by torquing the bolt to a pre-determined level, right?

Well, yes and no...

Turning the fastener to a predeterimined rotational torque just gets us in the ball park.

The rotation of the bolt will advance it down the helix of the threads due to the spiral wedging effect of the threads against each other. As we rotate the bolt, the entire bolt advances into the hole, stopping only when the underside of the bolt head reaches the surface of what we're going to clamp with it. It's finger tight at this point. Further rotation will still advance the threaded end, but the head contact will prevent the rest of the bolt from advancing any further into the hole. This begins to stretch the bolt, which creates the installed tension we're looking for. Continuing to twist the bolt increases the installed tension fairly predictably for a bit, and then we reach the yield point of the bolt. Continuing to twist the bolt will actually cause permanent deformation (elongation) from the threaded portion to the underside of the bolt head. At that point, the results are somewhat unpredictable ...if you continue, the bolt can stretch, the threads could strip, the bolt could break,..etc..

Anyway, what we're looking for is a specific installed tension, one that will clamp the parts together securely, not allow the heat and vibration to loosen it, and not cause undue stress on the threads etc..

There are so many extra variables that will directly affect the rotational friction, (and thus indirectly, installed tension,) that the mission critical bolts require special attention to detail. Most really good engine builders measure rod bolt stretch, for example, as opposed to rotational torque.

Depending on the condition of the threads, the lubricity of the lubricant used, and several other factors, such as the condition of the shoulders of the hardware where it meets the washer, or other surface it bears against, the installed tension can vary significantly at the exact same rotational torque, due to the effects of friction between the various surfaces.

Our only defense against this is due caution when assembling the engine internals.

Be carefull with your hardware during the cleaning process. Do not allow the hardware to bang against each other. This will burr/ding the threads, making torque inaccurate.


Inspect the bolts carefully. You can field check the threads for damage by using a thread pitch gauge. You can also check them by meshing them with a new bolt, thread to thread. Look for engagement over the entire length of the threaded section.

I prefer to use a new nut, or the thread chaser nuts that come in the thread repair kits, to clean the male threads on the bolts. I don't like to use the wirewheel method on mission critical hardware, as it really works the threads over. (I do use it on external hardware)


Check the bolt/nut shoulders and washers for damage. Damage here will dramatically increase friction, which won't help us get an accurate torque/installed tension.

A burred connecting rod nut can be turned upside down.

Use a lubricated thread chaser on all the engine female threads. I don't like to use a tap, even a bottoming tap. They tend to remove metal, as they're meant to cut new threads in a smooth hole. And, most taps are generally tapered down towards the leading edge, so the last few threads won't get cleaned up well. Follow up with a couple of squirts of brake clean. Make sure you blow all the spurf out of the holes, (and wear safety glasses if you use compressed air.)


The head bolt holes will very likely have some goo/old dinosaur spooge down in the bottom. This is oil that has wicked it's way down the threads due to capillary action, and then been turned into sludge by heat and time. I usually turn the motor upside down, and use a baby bottle brush and some brake clean. You must remove all this accumulation, as you can quite easily liquid lock your new lubricated hardware against it, as some of your oil from the head bolt will drain off and fill the block cavity. This results in lower installed tension, and the result may be lifting your head/head gasket failure. Use the thread chaser several times and clean it in between each pass. It's very important to get these holes clean!!! It's a very repetative job, that will go quicker with an electric screwdriver.

I usually fill a small cup with clean, fresh engine oil, and just dip my hardware in it. Wipe down the entire bolt with your fingers. It just has to have some oil on it, both on the threads, and under the bolt head. It doesn't need to be totally slobbered up, and dripping. In fact, too much oil can liquid lock fasteners, so use some common sense.

If you use aftermarket hardware it is imperative you follow their directions. They may use a different lubricant, (or in the case of studs into the block, loc-tite), and this dramatically affects the torque used. Follow the directions from your hardware manufacturer as to torque values if different then the o.e. torque chart.

Jamiestsi is completely correct, assemble anything with loc-tite quickly, as loc-tite cures in the absence of air and will begin to set up immediately. You want everything aligned like it will be in service before the loc-tite sets up.

Just make sure everything is clean at the mating surfaces, as any grit/dirt/dog hair will prevent the parts from seating correctly.


As to loc-tite on the outside the of motor, use your own best judgement. There are many grades of loc-tite, and I find I use the blue (medium strength) the most. It allows for easy dissassembly further down the road, and yet still prevents problematic hardware from loosening in service.

Just remember, loc-tite goes on clean and dry threads.

Good luck, and let us know how your first motor turns out!

 

[Defiant]

This begins to stretch the bolt, which creates the installed tension we're looking for. Continuing to twist the bolt increases the installed tension fairly predictably for a bit, and then we reach the yield point of the bolt. Continuing to twist the bolt will actually cause permanent deformation (elongation) from the threaded portion to the underside of the bolt head.

Some modern fasteners are "torque-to-yield" designs. And I'll never be comfortable with it. They are not supposed to be re-used.

 

[groundPork]

The torque charts you use assembling an engine's internals are all predicated on the threads being clean and coated with engine oil.

The installed tension from the same rotational torque will change significantly if you use loc-tite, as it has a different lubricity.

Since this is your first motor build, a word or two about what we're trying to do when we torque engine hardware may be helpfull here.

The goal is to provide sufficient tension/clamping force to keep jointed parts from moving relative to each other. This is done by torquing the bolt to a pre-determined level, right?

Well, yes and no...

Turning the fastener to a predeterimined rotational torque just gets us in the ball park.

The rotation of the bolt will advance it down the helix of the threads due to the spiral wedging effect of the threads against each other. As we rotate the bolt, the entire bolt advances into the hole, stopping only when the underside of the bolt head reaches the surface of what we're going to clamp with it. It's finger tight at this point. Further rotation will still advance the threaded end, but the head contact will prevent the rest of the bolt from advancing any further into the hole. This begins to stretch the bolt, which creates the installed tension we're looking for. Continuing to twist the bolt increases the installed tension fairly predictably for a bit, and then we reach the yield point of the bolt. Continuing to twist the bolt will actually cause permanent deformation (elongation) from the threaded portion to the underside of the bolt head. At that point, the results are somewhat unpredictable ...if you continue, the bolt can stretch, the threads could strip, the bolt could break,..etc..

Anyway, what we're looking for is a specific installed tension, one that will clamp the parts together securely, not allow the heat and vibration to loosen it, and not cause undue stress on the threads etc..

There are so many extra variables that will directly affect the rotational friction, (and thus indirectly, installed tension,) that the mission critical bolts require special attention to detail. Most really good engine builders measure rod bolt stretch, for example, as opposed to rotational torque.

Depending on the condition of the threads, the lubricity of the lubricant used, and several other factors, such as the condition of the shoulders of the hardware where it meets the washer, or other surface it bears against, the installed tension can vary significantly at the exact same rotational torque, due to the effects of friction between the various surfaces.

Our only defense against this is due caution when assembling the engine internals.

Be carefull with your hardware during the cleaning process. Do not allow the hardware to bang against each other. This will burr/ding the threads, making torque inaccurate.


Inspect the bolts carefully. You can field check the threads for damage by using a thread pitch gauge. You can also check them by meshing them with a new bolt, thread to thread. Look for engagement over the entire length of the threaded section.

I prefer to use a new nut, or the thread chaser nuts that come in the thread repair kits, to clean the male threads on the bolts. I don't like to use the wirewheel method on mission critical hardware, as it really works the threads over. (I do use it on external hardware)


Check the bolt/nut shoulders and washers for damage. Damage here will dramatically increase friction, which won't help us get an accurate torque/installed tension.

A burred connecting rod nut can be turned upside down.

Use a lubricated thread chaser on all the engine female threads. I don't like to use a tap, even a bottoming tap. They tend to remove metal, as they're meant to cut new threads in a smooth hole. And, most taps are generally tapered down towards the leading edge, so the last few threads won't get cleaned up well. Follow up with a couple of squirts of brake clean. Make sure you blow all the spurf out of the holes, (and wear safety glasses if you use compressed air.)


The head bolt holes will very likely have some goo/old dinosaur spooge down in the bottom. This is oil that has wicked it's way down the threads due to capillary action, and then been turned into sludge by heat and time. I usually turn the motor upside down, and use a baby bottle brush and some brake clean. You must remove all this accumulation, as you can quite easily liquid lock your new lubricated hardware against it, as some of your oil from the head bolt will drain off and fill the block cavity. This results in lower installed tension, and the result may be lifting your head/head gasket failure. Use the thread chaser several times and clean it in between each pass. It's very important to get these holes clean!!! It's a very repetative job, that will go quicker with an electric screwdriver.

I usually fill a small cup with clean, fresh engine oil, and just dip my hardware in it. Wipe down the entire bolt with your fingers. It just has to have some oil on it, both on the threads, and under the bolt head. It doesn't need to be totally slobbered up, and dripping. In fact, too much oil can liquid lock fasteners, so use some common sense.

If you use aftermarket hardware it is imperative you follow their directions. They may use a different lubricant, (or in the case of studs into the block, loc-tite), and this dramatically affects the torque used. Follow the directions from your hardware manufacturer as to torque values if different then the o.e. torque chart.

Jamiestsi is completely correct, assemble anything with loc-tite quickly, as loc-tite cures in the absence of air and will begin to set up immediately. You want everything aligned like it will be in service before the loc-tite sets up.

Just make sure everything is clean at the mating surfaces, as any grit/dirt/dog hair will prevent the parts from seating correctly.


As to loc-tite on the outside the of motor, use your own best judgement. There are many grades of loc-tite, and I find I use the blue (medium strength) the most. It allows for easy dissassembly further down the road, and yet still prevents problematic hardware from loosening in service.

Just remember, loc-tite goes on clean and dry threads.

Good luck, and let us know how your first motor turns out!

Agree 100%... I'd also like to add that your typical torque wrenches do not in fact measure actual torque, but resistance caused by friction... Look at the huge difference in torque requaored for ARP fasteners from their moly lube to engine oil. Then if you have some look at the mayonase like thickness of moly, and it will become clear.