Water ingested into a vehicle’s engine will not only affect performance, it could stall the engine and even damage it. In some worse case scenarios and in particular with diesel engines, water can cause costly damage.
Water is incompressible and if this water gets into the cylinder chamber, it may stall the engine and potentially bend a connecting rod or worse. The damage potential could be increased exponentially with higher compression ratios. For example; a low compression petrol engine may possibly be restarted, by removing the plugs and cranking the starter motor so the water can be spit out (mind you – this doesn’t always work). With high compression engines of 20:1 or higher as in some diesels, water in the intake can have dire consequences. The damage to these engines from just a small amount of water (e.g. half a cup) could potentially end up in the thousands of dollars.