Water pump dying??

What signs would tell you that the water pump was on its way out??  In my 78 k5 with 350, after i rebuilt the heads about 2 months ago, i heard a noise i had never heard before, its kinds like low whine but not too much and it also sounds like ....... ugh its hard to describe....... sound kind hollow if that makes sense, i think its the noise that the bearings would make when they are going out but whats odd is that the truck has been making that noise now since the heads were rebuilt but still no failures or overheating..... i might be taking the blazer out to glamis for thanksgiving  and don't want find problem in the middle of the desert, any help is greatly appreciated........  
solid axle chevys cant be beat
78 K5: 350 V8,700r4,np208, 8 lug D44 4:88, 14 bolt 10.5 4:88 with detroit locker and 35 inc parenelli jones dirt grip tires

get a really log screwdriver over 1' long and use it like a poor mans stethascope if the pumps bad youll hear a hallow growl coming up through the driver...mine was bad in my 74 C10 W/350 and what I did to find out...  
IT WASNT ME, IT WAS THE ONE ARMED MAN!

Water pumps either sing or leak when they are going bad and they are cheap to replace and too important in function to risk letting them ride for a while.  

keithpapa:
get a really log screwdriver over 1' long and use it like a poor mans stethascope if the pumps bad youll hear a hallow growl coming up through the driver...mine was bad in my 74 C10 W/350 and what I did to find out...

Thats exactly waht it sounds like, a hollow growl, so im prettty sure its the pump so off it comes...... thanks guys    
solid axle chevys cant be beat
78 K5: 350 V8,700r4,np208, 8 lug D44 4:88, 14 bolt 10.5 4:88 with detroit locker and 35 inc parenelli jones dirt grip tires

they are so cheap and easy to install its great  
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You know I love you all (in a manly non sexual way) Spawn_X

thats the joy of the gm 350...cheap easy to fix and if done right the most reliable engine ever made or put back together.  
IT WASNT ME, IT WAS THE ONE ARMED MAN!

amen    may the small block be with you  
solid axle chevys cant be beat
78 K5: 350 V8,700r4,np208, 8 lug D44 4:88, 14 bolt 10.5 4:88 with detroit locker and 35 inc parenelli jones dirt grip tires

Geo450racer:
What signs would tell you that the water pump was on its way out??  In my 78 k5 with 350, after i rebuilt the heads about 2 months ago, i heard a noise i had never heard before, its kinds like low whine but not too much and it also sounds like ....... ugh its hard to describe....... sound kind hollow if that makes sense, i think its the noise that the bearings would make when they are going out but whats odd is that the truck has been making that noise now since the heads were rebuilt but still no failures or overheating..... i might be taking the blazer out to glamis for thanksgiving  and don't want find problem in the middle of the desert, any help is greatly appreciated........

Hi,
Water Pumps often creates problem. I can understand your problem because 6 months ago my water pump has create sound problem but now it’s solved cause of Toyo Pumps. Because I purchased UNBEATABLE HIGH PRESSURE Pump from Toyo pumps   (www [dot]toyopumps[dot]com/horizontal-dbh[dot]html).It’s Easy maintenance features easy to clean, easy removal by means of jacking screws. Toyo Pumps has booster pumps, dewatering pumps, positive displacement pumps and submersible parts also available.
Thanks,

John
http://www.toyopumps.com