I have an R reg Vauxhall astra which is over heating. We have removed the thermostat, the fan is working but the engine overheats really quickly. The water comes out the top of the bottle and often turns to steam. Would this just be an airlock or something more serious
First, the t-stat should be replaced. If cooolant travels too fast, it doesn't have time to cool down. Next, with the engine cold and the engine off, remove the rad cap. Start the engine. If coolant comes shooting out, you have a bad headgasket.