Damn water pump!

[The MaDDeSTMaN]

The other day, I decided to replace the water pump on my 2L Mk II Escort, as it had started leaking between the pump itself and the block, and therefore it was losing coolant and pressure in the cooling system, and of course getting a bit too hot after running for 5 minutes or more. I thought to myself I might as well replace the entire thing, seeing as the old one is probably not exactly in the best condition.

Pulled the old one off, and yes indeed, I was right, it wasn't exactly in the best condition anymore, the imprellor blades were corroded down to almost nothing - basically if I hadn't replaced it then anyway, it would have needed to be replaced soon enough anyway.

While pulling it off, I noticed (after pulling out the radiator and everything else covering it) that the reason it had been leaking was because one of the bolts holding the water pump on had come undone, and was now missing! :

Long story short, I ended up getting another bolt to suit, put it in, and as it was getting nice and tight, it suddenly became a lot easier to turn. To the point where I can easily turn it with my fingers. Keep in mind that this bolt is holding the water pump to the block of the engine, and the cooling system is pressurised, so when the engine is running, that bolt is working against the pressure of the cooling system.

And the bl*ody thing won't hold the water pump in place! :

Anybody got any ideas, or experienced this problem themselves? I'm wondering if the thread that the bolt screws into on the block is ruined, if this is possible, and if it is, what can I do about it - I'm not exactly in a financial position to be able to afford to replace the block itself. :(