Attention: TDR Forum Junkies 
MarkEagleUSA
TDR MEMBER
After warming up to 34°, I bit the bullet and went out in the rain to flush the core another time. I disconnected the hoses and flushed back and forth about 5 times. Then I connected to the outlet side and just let the water run while I replaced the t-stat. It looked aftermarket and nowhere as beefy as the Cummins part. That might have been the easiest t-stat replacement I've ever done. Once I buttoned that all up I went back to the core and flushed back and forth a few more times. Water was running clear in both directions with no visible loss of pressure on either side.
Next, I topped off the radiator and started the truck. Using a stick between the pedal and the seat I bumped the RPM's up to about 12 for 5 minutes or so. Topped the radiator off again, put the cap on, and took her for a ride. Heat was fair and kept getting better as the truck temp came up. Once it approached normal, the heat was certainly better than warm but still not as hot as I think it should be. There is a drastic improvement over what it was but I'm hedging my bet for now since it is in the mid 30's.
While I was riding around, I stopped at the parts store and picked up a new radiator cap as the seal on the old one had a serious indentation all the around. Drove home and carefully removed the cap to install the new one. While it was off, and with the truck at operating temperature, I looked into the radiator but could not see any real movement of the coolant making me wonder if in fact I do have a water pump problem. There certainly seems to be a flow problem. At a minimum I think the system needs a complete flush and refill. Unfortunately, that needs to wait until spring unless we get a decent warm spell with some advance notice.
For now I'll just see how the heat performs and whether or not there's any real improvement. Temps will dip down to the high 20's/low 30's over the next couple of days. We'll see what to coming week brings.
Thanks to everyone for the tips and advice thus far, and for putting up with my barrage of questions.
Next, I topped off the radiator and started the truck. Using a stick between the pedal and the seat I bumped the RPM's up to about 12 for 5 minutes or so. Topped the radiator off again, put the cap on, and took her for a ride. Heat was fair and kept getting better as the truck temp came up. Once it approached normal, the heat was certainly better than warm but still not as hot as I think it should be. There is a drastic improvement over what it was but I'm hedging my bet for now since it is in the mid 30's.
While I was riding around, I stopped at the parts store and picked up a new radiator cap as the seal on the old one had a serious indentation all the around. Drove home and carefully removed the cap to install the new one. While it was off, and with the truck at operating temperature, I looked into the radiator but could not see any real movement of the coolant making me wonder if in fact I do have a water pump problem. There certainly seems to be a flow problem. At a minimum I think the system needs a complete flush and refill. Unfortunately, that needs to wait until spring unless we get a decent warm spell with some advance notice.
For now I'll just see how the heat performs and whether or not there's any real improvement. Temps will dip down to the high 20's/low 30's over the next couple of days. We'll see what to coming week brings.
Thanks to everyone for the tips and advice thus far, and for putting up with my barrage of questions.
).
