it could be... generally they start leaking before they stop pumping. thereshould bea steel impeller on the back of the pump. if it's plastic (could be the original) then they could have broke off and cause your problem. some car mfgrs use plastic for some dumbass reason...

 

ok thanks for the advice. When i get ready to do the timing chain ill swap the pump with a new one.

 

When i did the timing chain i replaced the water pump. I then added and bleed the coolant system and im having the same problem. At idle luke warm air, when driving, hot air. im leaning to the heater core but could there be any other causes for this?

 

no one has a clue i guess

 

it sounds like you have air in the cooling system... do this... put the rad fill neck as high up as you can, and add coolant until i'ts full. rev the motor to about 1200~1500 rpms and re-fill if it goes down. my bet is it will. the goal here is to push the air pockets out of the motor and get the coolant level up all the way to full.

 

Yah i hear you, but ive done that. The truck has 175k on it and im starting to think its the heater core. Something im not going to replace because i just dont have the time or energy.