Nissan Repair: thermostat issues on 96 pickup, alternator pulley, ooo miles

Question
I put a new thermostat , radiator flush, and new hoses in 2,000 miles ago, it
ran great for 2,ooo miles, then the truck began to over heat like it did before i
changed out the thermostat. It bubbled up the over flow tank with fluid. I
suspect the water pump is failing and sending debris into the thermostat and
causeing it to malfunction, So i am odering up a new water pump and
thermo. Just wanted to get an opinon on my thoughts, and if this has
happened to you before on a car or truck. Also on a different issue, the
altenator belt gets hung up sometimes and does not spin the atenator, the
tensioner is new and so is the altenator, I suspect the pully is not the proper
one, but it came on the altenator, and at the time I thought it would be the
same pully, so I did not think twice, Is this a common issue with altenators
you buy that are not oem.

Answer
Hi Chris -

Several thing may cause overheating besides the Tstat -

Check the cooling fan operation. If you have 2 fans, one should go on when you turn the A/C on, and the other goes on when the engine warms up. If it doesn't, then it is either the fan motor or the fan switch. I will walk you through the troubleshooting if this is so, let me know.

As for the alternator, is the belt loose? If not, check the alternator pulley for binding, or freezing. Do you have a serpentine belt, or Vbelt? I would remove the belt and check the idler pulley, alternator pulley, and any pulley that is run by that belt.

Hope this helps -
aloha
calvin