The right sealant in the right place is the difference between an oil-tight rebuild and a constant slow drip onto the driveway. Classic engines and gearboxes use a mix of paper, fibre and cork gaskets at most joints, but several joints, the sump rails, the rocker cover, the timing cover, and the water-pump-to-block face among them, benefit from a sealant applied to the gasket faces, and a few joints are designed as bare-metal dry joints sealed entirely by chemical sealant rather than a gasket.
Silicone RTV Sealants
Silicone room-temperature-vulcanising (RTV) sealants are the modern workhorse for any joint where a gap-filling, flexible, oil-resistant sealant is needed. Applied as a bead to the cleaned gasket face, the silicone cures to a tough flexible film that bridges small surface imperfections and remains oil-tight across the temperature range of a running engine. Black RTV is the typical choice for engine and gearbox work, oil and temperature resistant, and forgiving of the modest surface preparation that a classic rebuild typically allows. Red RTV is higher-temperature rated and is the right choice for exhaust manifold gaskets and turbo applications where the joint sees genuine sustained heat.
Hylomar and Non-Setting Sealants
Hylomar is the established non-setting sealant for joints that need to be sealed but also need to be serviced periodically, water pumps, thermostat housings, carburettor flange gaskets and similar joints where a fully-cured silicone would make later disassembly difficult. Hylomar remains flexible and tacky for the life of the joint, sealing reliably while allowing the parts to be separated cleanly when service is required. It is also the right product where a sealant needs to remain compatible with petrol or coolant, Hylomar is rated for both, where some silicones will harden or soften depending on the fluid in contact with them.
Specialist Sealants and Threadlockers
The wider range covers the specialist products needed for less common applications, Loctite threadlockers for studs and fasteners that need to stay tight under vibration, anaerobic flange sealants for dry-joint gearbox cases, copper-based exhaust manifold sealants and the cylinder-head studs and head-gasket dressings used during an engine rebuild. The technical team is available to advise on the right sealant for any specific joint.