GM-GMC: 95 S10 2.2liter repair, clutch fan, frost plugs

Question
I think my water pump went out. my truck leaked about a gallon of coolant on the ground yesterday when i parked it. Today I started it and looked for a leak underneath.... nothing. The tempature got twice as high as normal.
Is the water pump easy to change? Do I need to drain all coolant first? Can i reuse the coolant?

Answer
Steve,

  Water pumps will leak a large amount an sometimes unexplainably sometimes and not others. But, If you lost that much coolant the reason you are not leaking anymore could be because there is no more to leak....this would explain the high engine temp. I would open the rad cap(engine cold not running)and fill you colling sytem with water.....since it will probably just leak out again. Hopefully once you fill it the leak will show itself and you can confirm that the waterpump is actually the leaky part. Frost plugs can burst or fall out and litarally dump all the engines collant out in a matter of seconds so really be sure that the pump is actually the problem. If the leak is not evident you may want to have a reputable shop pressure test your cooling system, this should find any stuborn leaks. Most 2.2L waterpumps are not too bad to change but you will need some special tools when it comes to removing the Clutch fan/(if equiped) You will loose most of the coolant left in the engine when you remove the pump, the pumps gasket surface must be cleaned/sometime dificult and time consuming without the right tools. Finally coolant can be re-used as long as its clean and the concentration is good or can be adjusted using straight coolant(a 50/50 mixture us most comon) The coolant can also be tested for acidity with a PH test strip that any reputatble shop should have on hand. Hope this helps!