K-Seal ST3501 Head Gasket Sealer 16 oz Pour & Go — Seals Blown Gaskets & Cracked Heads, Ceramic Micro‑fibres

K-Seal ST3501 Pour & Go Head Gasket Sealer (16 oz) is a ready-to-use engine coolant stop-leak that seals blown head gaskets, cracked heads and porous engine blocks without disassembly.

When a coolant leak threatens your engine, the ST3501 bottle offers a fast, simple repair option. The formula builds on K-Seal's proven chemistry with 33% more sealing power than the regular formula and ceramic micro-fibres designed to lodge into holes and form a durable seal. It’s packaged as a 16 oz pour‑and‑go treatment that mixes with the coolant system, letting you address leaks without removing the head or taking the vehicle out of service for extended repairs.

How does this product actually stop a blown head gasket?

The ST3501 works by circulating with the coolant where ceramic micro-fibres and reactive polymers locate the leak and establish a flexible, long‑lasting barrier. It is formulated to find holes, cracks and porous metal and then bond to the metal surface to block coolant escape while still allowing normal heat transfer.

• Contains ceramic micro-fibres that lodge into gaps up to 0.64 mm wide.
• Reactive polymers cure in the cooling circuit to form a resilient seal.
• Blend is engineered for use without dismantling the cylinder head.

Will it work with my vehicle’s coolant and engine materials?

K-Seal ST3501 is compatible with all common engine coolants and a wide range of engine metals and alloys used in cars, light trucks and some heavy‑duty machinery. That versatility makes it a useful option for mixed fleets or older vehicles with unknown coolant histories.

• Safe with traditional and extended-life antifreezes.
• Formulated to work with cast iron, aluminium and other engine block materials.
• Suitable for many passenger vehicles and some heavy-duty applications.

How do I use the 16 oz pour-and-go bottle for best results?

Using ST3501 is straightforward: add the bottle to a warm, but not hot, cooling system and allow the engine to idle or be driven gently to circulate the product. Follow the product instructions if you see bubbling in the radiator or reservoir; bubbling can indicate an over-pressurized system and may require specific steps to release pressure and improve sealing performance.

• Add to a warm system per label directions and run engine to circulate the formula.
• Monitor coolant level and temperature while the product works.
• Consult technical guidance if persistent bubbling or pressure issues occur.

What kinds of leaks and damage can this sealer repair?

ST3501 is designed to address leaking head gaskets, small cracks in cylinder heads, and porous or cracked engine blocks where coolant is escaping. It’s not a substitute for mechanical repairs in every case, but it can eliminate the need for immediate disassembly in many common coolant leak scenarios.

• Effective on blown or leaking head gaskets where coolant loss is present.
• Seals small cracks in heads and micro‑porosity in blocks up to 0.64 mm.
• Useful as a temporary or long‑term fix depending on damage severity.

Who is this for: K-Seal ST3501 is aimed at vehicle owners, fleet managers and mechanics who need a fast, user-friendly coolant stop‑leak option to avoid immediate head removal. It suits cars and light trucks with coolant leaks, older vehicles with uncertain maintenance histories, and operators of heavy equipment that require downtime reduction. For severe structural damage or persistent overheating, pair the product with professional diagnosis to determine whether mechanical overhaul is necessary.