J-B Weld Red Hi-Temp RTV 100% Silicone Professional Grade Sealant. This room-temperature vulcanized (RTV) silicone is specifically designed to create reliable, flexible, and leak-proof gaskets or seals in high-heat environments.
Withstands continuous temperatures up to 550°F (287°C) and intermittent peaks up to 650°F (343°C).
It features a 1-hour set time (tack-free within minutes) and typically reaches a full cure within 24 hours depending on temperature and ambient moisture.
Made of 100% silicone. It resists shrinking, cracking, weathering, and oil splash. It is also completely sensor-safe for automotive electronics.