did my kdp today (5hrs later ) and basically ended up pulling the rad to get at it cause pulling the intercooler and sliding the rad back did not seem to work at all for me. anyway i lost a bunch of coolant, and i filled it back up, but now the temp cycles when i drive it. up to 90, then right away back to 70. then a climb back to 90, then drop. i assume i have an airlock? but how to get it out? i checked the coolant level after some driving and it was almost at the top of the rad, but no pressure was built up. any insight is greatly appreciated.

PS now i can go crazy on the power mods!!

 

They do this normally, depending on thermostats. My original stat would cycle from 170-190 for hours on end. My new one is steady as a rock though. Unless you can't get to temp, or you're overheating, I wouldn't pay any mind to it.

 

I would take the radiator cap off and allow the truck to idle with the heat on from a cold start until the thermostat opens. This can take a while on these trucks. I use a blanket/moving pad to block off the radiator/intercooler to speed up this process. If there is any air in the system this will allow it to escape, you may have to top off the radiator with coolant/antifreeze when your finished.

Other than that my temp gauge fluctuates often. Normal....

 

Unless it's hot out mine doesn't get warm enough to open the thermostat idling, but never the less it's normal for them to fluctuate as said above

 

is your belt on right? maybe the water pump pully is slipping?

 

actually the issue seems to have disappeared. must have just been pumping the bubbles out at first

 

Unless you fill the coolant with the nose of the truck pointed uphill there will be air in it.
Refilling with the engine running, which isn't recommended by Cummins, makes it worse.
I've found as long as long as the overflow bottle is kept up to level that all the air eventually works it's way out.