Loctite 515 Gasket Maker Flange Sealant Tube — 50 ml, anaerobic form-in-place, medium-strength flexible seal

Loctite 515 is a medium-strength, anaerobic-forming gasket maker designed to create flexible, form-in-place seals on rigid machined metal flanges with gaps up to 0.25 mm.

Built for professional automotive and industrial use, Loctite 515 replaces pre-cut gaskets and cures in the absence of air to form a reliable seal that moves with mating surfaces. OEM-approved and lab-tested by Henkel, this methacrylate-based sealant is commonly applied to pumps, thermostat housings, transmission pans, compressor housings and axle covers. It offers a balance of fixture speed and shear strength suitable for many routine flange sealing tasks.

How does Loctite 515 form a gasket on machined flanges?

Loctite 515 is applied as a bead or smear to clean, rigid flange faces; when the parts are assembled and air is excluded, the product cures anaerobically to a rubber-like gasket. The cured material bonds to metal and fills small flange irregularities to stop leaks without pre-cut gaskets.

• Applies directly from a 50 ml tube for controlled bead placement.
• Cures where oxygen is excluded after assembly.
• Fills gaps up to 0.25 mm (0.015" approximately).
• Forms a flexible seal that tolerates minor flange movement.

What vehicles and parts is this gasket maker suitable for?

This product is intended for machined metal components that require a form-in-place gasket rather than a preformed material. It is widely used across gasoline and diesel engines on parts where manufacturers accept anaerobic gasketing solutions.

• Common uses: water pumps, thermostat housings, transmission pans and case covers.
• Also suited for transaxle casings, compressor housings and axle covers.
• Replaces paper, rubber, cork and other pre-cut gaskets in approved applications.
• OEM-approved where 515 or anaerobic gasketing is specified.

How strong and fast is the cured seal?

Loctite 515 provides medium tensile shear strength and a practical working and fixture window for assembly operations. It balances secure bonding with sufficient flexibility so sealed flanges can experience normal service movement without the gasket failing.

• Typical tensile shear strength: about 6 N/mm².
• Medium cure speed with approximately 30 minutes fixture time in typical joint configurations.
• Forms a resilient, oil- and fluid-resistant gasket after full cure.
• Designed for metal-to-metal rigid flanges rather than soft or highly flexible mating faces.

How should I prepare surfaces and apply the product for best results?

Surface preparation and correct application are key to reliable sealing. Clean, dry, and oil-free flange faces promote good adhesion and consistent cure; then apply a continuous bead or pattern suited to the flange geometry before assembling parts.

• Remove old gaskets, oil, grease and loose debris; use appropriate cleaners.
• Apply a continuous bead around the flange mating surface; avoid excessive squeezout.
• Assemble parts within working time so the anaerobic cure can occur under compression.
• Allow specified fixture and full cure times before pressurizing or returning to service.

Who is this product for?

This 50 ml tube of Loctite 515 is aimed at professional mechanics, automotive technicians, race teams and experienced DIYers who need an OEM-approved anaerobic gasket maker for machined metal flanges. It's ideal when a form-in-place, flexible seal is preferred over cutting and fitting traditional gaskets—especially for water pumps, thermostat housings, transmissions and other rigid metal assemblies where manufacturers permit anaerobic gasketing. If you require rapid fixture time combined with a resilient, medium-strength seal that withstands normal engine and driveline service conditions, Loctite 515 is an appropriate choice.