The mechanical seal probably needs to be replaced, or it may be the seal plate gasket. if it is the seal it will eventually ruin the pump motor if not replaced. Go to you tube for a how to videoPOOLCENTER.com - Hayward Pool Pump Impeller-Seal Replace 2
Only replace the water pump if you have a visible external leak, the water pump bearings are bad, or the shaft is broken.
The water pump should only be replaced when you hear signs of the pump failing, i.e: bearings on the pulley are squeaking.
Replace the pump, your bearings are shot and it needs to be replaced before the pump flies apart sending your fan through the radiator.
Replace or rebuild the engine. In all but the most obscure cases, low oil pressure is caused by worn bearings. Replacing the oil pump won't help.
If the car is over heating or if a sound that shouldn't be there can be heard due to worn out pump bearings.
There is a drain or dribble hole in the case at the bottom under the shaft. Is there wet or staining? Yes means bad seal, replace pump.Grab the pump pulley and rock it up and down or side to side, any movement that you can feel means the bearings have failed. Replace pump.Spin the pump, and growl or scrape means the bearings are bad. Replace pump.A slight whine is normal on the spin test from the seal.
If it is making a noise or leaking then it is defective. The only real fix is to replace it. You can rebuild one, but it is not advisable.
Near the bottom of the oil pan. There isn't really much point in replacing the oil pump without checking out the bearings. Get a little plastiguage and check the bearing tolerances. You can't do any good replacing the oil pump if the bearings are worn.
Either the pump bearings are bad or the ac clutch is going bad. The clutch can be replaced but the pump bearings are not generally cost effective to change.
how to replace wheel bearings on 2004 GMC envoy?
More than likely the bearings in the fuel pump are failing. This is sometimes one of the first signs you will hear just before the fuel pump locks up. Replace the fuel filter ASAP. If the whining is still there, replace the fuel pump. A clogged fuel filter will overwork the pump, and sometimes cause it to whine.