Hello. Since the freeze last week, my engine is not cooling. I suspect it is water pump related as it sounded like a belt screeching when I first started it after a very cold night. It runs ok at low speed / short distance,  it it does overheat, and the fan kicks in and stays on after switching off. Is there any thing I can do to see if it's the water pump, or maybe belt tension, before submitting myself to the mercy of a garage. I had timing belt replaced just over a year ago, and am worried that they may need to do the whole job, just to fix the issue, which isn't feasible financially.

Hi,

Good news is the waterpump is separate to the timing belt on this engine, so the garage won't need to do the timing belt again.

The aux belt is tensioned automatically by a spring, so I doubt that's become faulty in the cold weather.  Also the alternator would not be charging if the belt was slack, so I think we can rule that out. 

If the belt is still intact and running around the pulleys then I think you are right about the pump impellor failing due to ice holding it inside the engine.  But that causes more concern as to why the coolant in the engine was frozen.  Did the garage not put enough anti-freeze in?  If the cooling system did freeze, and the only damage is the waterpump, then you have been lucky.