Below the radiator of my 2001 2wd Blazer is a component that I have not seen before. The 2000 that I had previously did not have it. Online parts vendors list auxiliary water pumps that are similar in appearance. Can someone explain what this does?

The car has run fine including towing a small travel trailer in flat country. A week ago I towed the same small trailer up a steep grade on I-17 and it overheated. After letting it cool for a length of time in a rest area, I turned around and went back down and home with no trouble. The car is now in Arizona and I am puzzling over it up in Washington state. I will have to deal with it when I get home in another 10 days.

 

It is not an auxiliary water pump and nothing by that name has been factory equipment on these trucks... If it is below the radiator, near the passenger side frame rail, it is the AIR (air injection reaction) pump. Your 2000 should have had it as well.

 

Many thanks Swartikk, I looked up AIR pump on the vendor sites and there was the exact part. Of course it has nothing to do with my overheating problem.

My suspicions now are fan clutch, fan and radiator. Since I have only had the car since last August, I have to wonder if the radiator might have been replaced with one that is undersize.