Bahahar yeah its all over youtube and google how to do it, and yeah I could do it,
BUT, I gotta buy $50 sealant plus $30 coolant, all of which the mechanic already has, the pump is at least 100
Mechanic price 175, my price at least 180
Regards.
You will have to pay for the coolant regardless and you don't need any sealant (unless some of the water pump holes go into the cooling jacket - I haven't done a V6 pump recently enough to recall if they do or not) as the gaskets have sealant microencapsulated on them (that's the red line near the edges of the gasket).
Replacing the pump
is easy, about as easy as anything gets on a car repair. On an old car it's
possible that you would have, say, a bolt break when it is being removed but that is unusual. It's also possible for someone without mechanical experience - feel if you like - to incorrectly tension the bolts. I get that you may not want to DIY but it's good to stretch sometimes and that makes a successful result even more rewarding.
There's no easy fix to a coolant leak that doesn't create further problems when the proper fix is made. The "temporary" cooling system "fixes" ie. stop leak products, don't work anyway.
If you do DIY, don't buy the cheapest coolant you can. V6 Commodores require a particular spec. for the coolant. There should be some description of it being suitable for use in V6 Commodore engines at the point of sale. You can always ask for assistance (and hope the correct answer is forthcoming). Most cheaper coolant is diluted; look at the concentration of ethylene glycol on the label so that you aren't just buying water.
You should use all the coolant required for the cooling system capacity (10L, at 50% concentration, = 5l of straight coolant) with demineralised water - available from hardware stores - to top up the additional volume with. Using demin. water isn't absolutely essential if your local water isn't hard.
The engine noise may be a pulley bearing or indeed the water pump bearing. With the exception of the A/C pulley and alternator bearings, which require some special tools, the pulley bearings (pulleys) are easy to replace DIY.