I have a leaky water pump on my 405 TD but need to drive 150 miles, mainly motorway. Never faced this before. Questions: 1. Can the leak get worse very fast? 2. Will the temperature guage - reliable up til now - get unreliable if the water gets very low? 3. Does speed make a difference to rate of leak? Obviously I want to set off with gallons of water on board and check and fill up at intervals as necessary. I've already put in K-Stop? K-Leak? but it didn't help much. Thanks.