How to remove a 2003 GMC Sierra water pump

I personaly dont see many water pump gaskets leak, but instead there is a weep hole that they leak from when they wear out. they are designed this way. which is common. reason it may leak with ignition off is now the pressure builds up verses being cycled through the engine and doesnt reall have time to squirt out.and it just finds a way out with engine off which would be your weep hole most likely.

Its not hard to fix or replace water pumps on the gas engines. there should be the large A/C and powersteering bracket that can be removed and sometimes if you dont have clearence the alternater bracket. its not very hard. basic tools work just fine. the only thing that may be alittle hard is the fan nut. you will need a large wrench and something to stop the pully from spining while loosening and tightening that nut. should take about 2 hours or so. IIRC13mmm, 15mm bolts, 9/16 bolts and 10mm and 8mm bolts. that all you need.other than the large wrench. pipe wrench will work but you need something to prevent the pulley from movning. thats very important.

Good luck. I hope i answered your question.
Michael

Water pump gasket, very common problem