Do Exhaust Manifold Studs/Bolts Need Loctite or Anti-seize? (Explained)

With time, exhaust manifold bolts or studs from your car’s exhaust system usually corrode, seize, wear and tear, then loosen.

Most car owners and drivers who find themselves in such situations with their manifold bolts usually wonder which products to use to prevent their bolts from seizing, galling, and corroding.

One question that usually pops out in their minds is: Do exhaust manifold studs or bolts need Loctite or anti-seize for the bolts not to seize, corrode or loosen even under high temperatures?

Let’s Find Out If Exhaust Manifold Studs or Bolts Need Loctite or Anti-seize

Yes, car exhaust manifold studs need Loctite to prevent seizing, galling, and corrosion of the bolts or studs. The Loctite also helps with lubrication for easier disassembly. This implies that there will be minimal damage to components during disassembling.

Car exhaust manifold bolt sprayed with loctite or anti-seize.

It is also vital to note that exhaust manifold bolts usually reach high temperatures like 800-900 degrees while functioning.

So, you must know the right anti-seize to use since different products are made to withstand different temperatures.

If you use the one not recommended for manifold bolts, it will just evaporate when the manifold bolts are at high temperatures.

While using anti-seize, always ensure you:

Apply Loctite or Anti-seize Sparingly

Always remember that the goal is to coat the bolts with Loctite to avoid corrosion and adhesion between the bolts and fasteners.

If you apply excess Loctite, it may lead to the accumulation of debris that may damage the manifold bolts and cause problems while disassembling the fastener.

Only use the necessary anti-seize on the bolts since further use does not mean it will give more corrosion protection, but it’s just product waste.

Minimize the Initial Torque Values by 25% to 30%

While it is usually forgotten, reducing the torque values by 25% to 30% is vital.

The amount of torque on the bolts is usually based on the equivalent clamping force.

Loctite usually acts as a lubricant, so the lubricating necessities normally reduce the recommended amount of torque so that you get the desired clamping force. It is also known as a torque multiplier.

Applying anti-seize while maximizing the required torque value will make the bolts stretch in extreme situations, which is not good for performance.

The required amount of torque reduction usually varies with the bolts, and you should engage a manufacturer or an expert when in doubt.

Only Use the Correct Loctite Type During the Application

Just as mentioned, there are different types of anti-seize for application.

Please choose the stable one, like copper Loctite whose electrical conductivity is top-notch.

Note: While many prefer using Loctite on bolts or studs, it is vital to understand that using this product on already damaged bolts is not good. Also, please do not use it to assist you with installing the fastener. In short, do not use anti-seize where it is not needed because if you do so, you are attracting the risk of doing damage.

Only use Loctite when dissimilar metals are at stake, like in those places where high heat leads to corrosion(manifold) and on fasteners that you usually remove regularly.

Remember, after assembly, wipe off excess anti-seize to remove contaminants that may damage the manifold.


Related:

Is Loctite or Anti-Seize Suitable for High-Heat Applications Such as Exhaust Manifold Studs or Bolts?

Yes, Loctite is suitable for high-heat applications like exhaust manifold studs or bolts. Normally, the exhaust bolts reach temperatures as high as 800 to 900 degrees for a medium load. That’s why an anti-seize comes in to prevent corrosion because of high temperatures.

It is also good to understand that anti-seizes are usually engineered to withstand various temperatures.

If you use the wrong anti-seize, it will evaporate when the manifold bolts reach very high temperatures, making them prone to corrosion and damage. That’s why it is advisable to utilize the correct product for great results.

Read this great related article: Is A Car Exhaust Manifold Heat Shield Necessary? (3 Signs Of Damage)

What Type of Loctite or Anti-seize Should I Use for Exhaust Manifold Studs?

Here are different types of anti-seize or Loctite to use for exhaust manifold bolts: Take a look.

Loctite TypeLoctite Description
Copper-based LoctiteIt is typically fortified with graphite and copper in grease. Copper-based Loctite copes with temperatures up to 1800F.
Silver grade LoctiteThis is made up of metallic flakes and graphite. The good thing with this Loctite type is that it won’t harden or evaporate even in too much heat or cold. Also, it withstands temperatures equivalently to 16ooF.
Nickel LoctiteIt is copper-free and a great option for stainless steel bolts, among other metals. It withstands temperatures equivalently to 2400F.

For those reusing exhaust manifold bolts, you will have to use a metal fortified Loctite for the studs or bolts though we do not recommend reusing bolts. On the other hand, if you are retrieving the broken bolts and ready for replacement, you can use OEM bolts for outstanding results.

For great impact, always ensure your surfaces are clean before application. Wipe off grease, oil, or contamination from the bolts or studs.

Use a brush to apply a thin layer of your preferred Loctite and ensure you have spread evenly. The brush should only be for applying the anti-seize you are using and not for other products to avoid contamination.

You may wonder if you have to apply the anti-seize periodically, but the answer is no. once you apply it, it will last for the performance interval of the interface. However, if you disassemble the fastener, you must clean the bolts and reapply the Loctite again.

When cleaning anti-seize from your manifold bolts or studs, you can use a standard industrial degreaser or a solvent cleaner for excellent results. Do not use abrasives, as they will damage your bolt’s surfaces.

What Other Methods Can I Use to Keep Exhaust Manifolds Studs or Bolts Secure?

Below are methods to keep exhaust manifolds studs or bolts secure. Have a look.

Lock Washers

Lock washers are metallic fasteners comprising steel and sometimes aluminum, phosphor bronze, or bronze. You can find lock washers in different types: stat washers and split washers.

The main function of lock washers is to hold the manifold bolts tight and prevent any slipping and loosening of the bolts because of vibration. They prevent the studs or bolts from rotating by giving extra security against torque and vibration.

When fixing the lock washer, ensure you do it correctly to hold the bolt in place. Fix the lock washer below the bolt or stud. It should create a tight connection. If you sense the connection is not tight, kindly press the bolt or stud down until you have acquired a tight connection.

You can use a wrench and rotate it clockwise to make the bolts tight but also in a manner they can be loosened when needed. Finally, you will check your washer to ensure it is performing efficiently, and just like that, you are good to go.

If you want to remove the lock washers someday, it’s simple unless they have stayed in position for an extended period. Then, you will need to spray some lubricant to loosen them.

However, in our case, you must take a flat screwdriver and loosen the lock washer. Remember to loosen the washer after removing the bolts.

You can only use lock washers once, so always discard them after removing them.

Rivet Backup Washers

You use rivet backup washers with pop rivets specifically for stainless steel bolts or studs. The washers have larger application diameters, giving a larger surface area and curbing any vibration by distributing force over an extended area.

While using rivet backup washers, it is usually advisable that you do not combine materials. Like if your bolts are made of stainless steel, you use a stainless rivet backup washer. Any mixing of tools usually leads to installation problems.

Fender Washers

These are round washers with very small inside diameter holes. They are extra thick, and you can use them to prevent pull-through and also gives a larger bearing surface below your manifold bolts or studs.

Here are more methods you can use to secure your manifold bolts:

Washer TypeWasher Description
Finishing Cup WashersThey normally form a cup for the head of the bolts to perfectly fit in and secure the studs. They give a finish flush to your bolts because they are shaped like a cup.
Flat Washers (extra thick)They are round with a hole made perfectly for the size of a bolt to secure the bolts. You use flat washers to help you distribute threaded bolts while the bolts are tightened.
Square WashersYou can get them in a square shape and might be beveled on one side and flat on the other. They prevent any vibration of the nuts and give a larger surface area with a great hold of bolts than standard round flat washers.

How Do I Prevent Exhaust Manifold Studs or Bolts from Breaking Once Secured?

To prevent exhaust manifold bolts from breaking once they are secured, kindly do the following:

  • Ensure no debris is accumulating around the secured bolts. If you see any, use pressurized air to remove the debris.
  • Refrain from using force to take out any bolt when you want to. You can use a spray or lube oil to soften it for easy removal without any breakage.
  • Regularly lubricate the joint parts to make the bolts not wear and tear.
  • When tightening the bolts, use an appropriate spanner or wrench to avoid any breakage.

Conclusion

Without a doubt, your exhaust manifold bolts need Loctite or anti-seize to prevent corrosion, galling, and seizing.

Always ensure you are using the correct Loctite for outstanding benefits. While applying your anti-seize, apply it sparingly or evenly using a brush.

Lastly, you have various anti-seize options, starting with silver grade to nickel anti-seize copper-free.

Use the one suitable for your manifold bolts or studs. Remember, different types of anti-seize are made to withstand different temperature amounts.

Sources

Should you Use Anti-Seize on Exhaust Manifold Bolts?

6 Tips for Effective Use of Anti-Seize Compound

How to Use Lock Washers

What is an Anti-Seize?