scottmn1

Does anybody know exactly what the difference is between the "upgrade" thermostat and a regular "off the shelf" by application thermostat that wannadiesel has listed in the sticky section? Is it a better quality stat, or is a different temp stat...or both?

Field_boss_cb

The general cummins population has not had good luck with the after market thermostats. Pay the extra and get the Cummins unit. Part # 83506401AA

csramsey640

BUT, before you pay the extra...search around. I had mine ordered in, and when I went to pick it up, was told $41!! I did have to blink a few times, but i never asked the price, so i caughed it up.

Found out a few days later, I could have had one at another dealer for around 21 bucks or so. Generally speaking, Our local cummins parts guy said he is not a dealer for the B series engines, so he cant get me great prices. He recommended a Ford or GM medium duty truck garage, since they have used the 5.9 in a few models over the years, and have better prices, which they did when i checked and had a few in stock.

Id say a full blown Cummins garage, would also have a better price. Just call around. You can give that Cummins # to a Ford/GM medium truck garage also.

The 1st thermostat I tried was a Stant, and all I got was a sweeping guage, and in the summer with heavy towing....pretty high temps. After I replaced it, I got a steady guage and good temps.