Put a new thermostat gasket in and put some of the blue sealant.
How long should I leave it before filling with water and running the engine ?
Sealant
Re: Sealant
What, the Hylomar type with a solvent or blue silicone? TBH, as long as it`s clamped down correctly I`m sure it`ll be OK. Prefer the Hylomar type myself as the solvent flashes off much quicker than silicone cures.