LOCTITE 263

Loctite 263

Strength: High temperature resistance, high strength, local heating is required during disassembly
Temperature range: 180°C
Maximum bolt size: M25
Packaging: 50 ml/250 ml
Color: Red
Viscosity (cP) at 20 rpm: 500
Thixotropy: No
Breakaway torque/average dismantling torque, M10 steel nuts and bolts (N.m, lb.in): 33/33 N.m ; 290/290 lb.in
Temperature range: -55°C to 180°C (-65°F to 360°F L3)
Fixture time (min): 10

Overview

Loctite 263 is a red, low-viscosity, high-strength anaerobic threadlocker based on acrylic (dimethacrylate ester) chemistry. It is formulated for the permanent locking and sealing of threaded fasteners, especially in heavy-duty applications such as studs into motor housings, nuts onto studs in pump housings, and other joints where maximum strength is required.

The product cures when confined between close-fitting metal surfaces in the absence of air, forming a tough, thermoset plastic that:

  • Prevents loosening from shock and vibration

  • Seals the thread helix against fluid and gas leakage

  • Helps protect threads from corrosion over time

Why choose Loctite 263?

1) Permanent locking for critical fasteners
Loctite 263 is classified as a high-strength, permanent threadlocker. Once cured, fasteners have very high breakaway and prevailing torque, making the product ideal where unplanned loosening is unacceptable, such as in powertrain, process equipment and heavy machinery.

2) Primerless on active and passive metals
Unlike older grades that often need a primer, 263 is engineered to work without primer on both active metals (steel, brass, copper) and passive substrates such as stainless steel and plated surfaces. This simplifies process steps and reduces consumables.

3) Oil tolerance for real-world production conditions
Loctite 263 offers robust curing performance and tolerates minor contamination from common industrial oils—cutting fluids, lubrication oils and anti-corrosion oils—on “as-received” fasteners. Heavy contamination should still be removed, but 263 is much more forgiving than non-oil-tolerant grades.

4) High temperature resistance
With a typical operating range from -65 °F to +360 °F (-55 °C to +182 °C), Loctite 263 maintains its locking and sealing performance in high-temperature machinery and engine compartments.

5) One-part, easy to apply, UV-fluorescent
Loctite 263 is a single-component liquid supplied in small bottles. It is red and fluorescent under UV light, which makes quality inspection and verification of application straightforward on the production line.

Typical Applications

Heavy-duty mechanical and process equipment

  • Studs in motor housings, engine blocks and pump housings

  • Fasteners in gearboxes, presses and heavy rotating machinery

  • Structural bolts on industrial equipment subject to high vibration

Powertrain, automotive and off-road

  • Critical engine and drivetrain fasteners that must not back off under load

  • Suspension and chassis bolts where high strength and sealing are needed

General permanent threadlocking & sealing

  • Metal fasteners where permanent retention and sealing are required

  • Replacement of mechanical locking devices (lock washers, split pins) in many designs

Loctite 263 is intended for metal-to-metal threads only and is not recommended for plastics or for use in pure oxygen or strong oxidizing environments.

How to Use Loctite 263

Step 1 – Surface preparation

  • Remove loose rust, old threadlocker and heavy grease.

  • Wipe or solvent-clean away thick oil and anti-seize.

  • Loctite 263 tolerates light oil films, but cleaner metal delivers more consistent, higher strength.

Step 2 – Product application

  • Shake the bottle briefly.

  • Apply a continuous bead of Loctite 263 along the male threads, covering the full engagement length.

  • For blind holes, apply some product into the female threads so it is pushed through the joint as the fastener is installed.

Step 3 – Assembly and tightening

  • Assemble parts and tighten to the specified torque.

  • Avoid re-adjusting once the product begins to fixture.

Step 4 – Cure and return to service

  • Fixture (handling) strength develops relatively quickly, but allow up to 24 hours at room temperature for full cure, especially on passive metals or in cooler environments, before subjecting the joint to full load or pressure.

Step 5 – Disassembly (if ever required)

  • As a high-strength, permanent grade, Loctite 263 usually requires:

    • Localized heating of the fastener area to around 250–300 °C (480–570 °F), where the base materials allow, to soften the adhesive.

    • Disassembly with appropriate tools while the joint is still hot.

Safety & Handling

Recent Safety Data Sheet information for Loctite 263 High Strength Threadlocker indicates that it:

  • Can cause serious eye irritation and skin irritation, and may cause an allergic skin reaction.

  • May cause respiratory irritation if vapors or mists are inhaled.

  • May be harmful to aquatic life with long-lasting effects.

Basic precautions:

  • Use only in well-ventilated areas; avoid breathing vapors, mists or sprays.

  • Wear eye/face protection and suitable protective gloves.

  • Wash hands thoroughly after handling; remove contaminated clothing.

  • Do not allow uncured product to enter drains or waterways.

  • Store in a cool, dry place away from heat, ignition sources and direct sunlight, in the original tightly closed container.

Always read and follow the latest SDS for your country/region before use.

FAQs

Q1: When should I choose Loctite 263 instead of Loctite 243 or 242?
Choose Loctite 263 when you need high-strength, permanent locking on metal fasteners, especially in heavy-duty, vibration-prone applications. Choose Loctite 243 or 242 when you want medium strength and routine disassembly with normal hand tools. 263 is a better fit when you want the joint to stay locked for the life of the assembly.

Q2: Is Loctite 263 really primerless and oil-tolerant?
Yes. Henkel describes 263 as a primerless, oil-tolerant threadlocker that works on both active and passive metals and tolerates minor oil contamination on “as-received” fasteners. However, heavy grease, thick oil or anti-seize should still be removed for best performance.

Q3: Can I remove fasteners locked with Loctite 263?
Loctite 263 is a high-strength permanent grade, so removal of large fasteners will typically require localized heating to around 250–300 °C and high torque with suitable tools. For assemblies that need frequent service, medium-strength threadlockers are recommended instead.

Q4: Does Loctite 263 work on stainless steel and plated hardware?
Yes. 263 is specifically designed to work on active metals like steel, brass and copper and passive metals such as stainless steel and plated surfaces, offering robust curing performance on both. Cure may be a bit slower on passive metals, so allow adequate time before full loading.

Q5: What fastener sizes is Loctite 263 best suited for?
Loctite 263 is commonly used on medium to large bolts and studs in heavy-duty applications—similar size range to other high-strength reds like 271, but the low viscosity and primerless/oil-tolerant design make it especially useful where you need deep wetting into standard thread gaps.

Q6: Can Loctite 263 be used on plastic or mixed metal/plastic threads?
No. Like other anaerobic threadlockers, Loctite 263 is formulated for metal-to-metal joints and may cause stress cracking in some plastics. It also does not cure properly on non-metallic threads. For plastic or mixed joints, use an adhesive designed specifically for plastics.

Q7: Does Loctite 263 also seal the joint against leaks?
Yes. By filling the thread gap, Loctite 263 locks and seals in one step, helping prevent leakage of fluids and gases along the helix and protecting against corrosion. It’s not a substitute for flange gaskets, but it is very effective for sealing through-thread paths.

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