Has this vehicle always been serviced with a G-05 HOAT formulated coolant?

 

sadly, i'm the third owner if this truck. i serviced it with ZEREX G-05 anti-freeze and it had the mopar orange stuff in it. the truck has 163,000 miles on it and i figured to do it the whole nine yards for peace of mind with a change and new thermostat. i let checked the flow to and from the core and no problems there. let the truck idle with the bleed screw that is in between number one and two open and got quite a bit of air out. i made sure to fill it back up. truck is now blowing better than luke warm, but not "burn you out; gotta turn it down" yet. i figure that it needs some more time. maybe one more drive down the highway will do the trick.

 

Make sure you got a 190 deg thermostat.

 

Yeah! Get it up to operating temperature then let it cool down for several hours. Once it's cool, open the radiator cap and top it off. You may have a small amount of air that has not escaped yet.

The Cummins thermostats are very reliable compared to those carried by parts stores. They are hit and miss when it comes to quality and reliability.

 

ok it's been sitting over night and the level hasn't dropped any. gonna run it up to full temp and see what happens. hopefully i got all the air out and i have heat finally. fingers crossed again.

 

i don't know where to go with this truck. i've done all the things that ya'll suggested and all the things the manual said to do. the radiator is still warm/hot on the driver side and cool/cold on the passenger side. i can't get any more air out of the system. i've even turned the bleed screw loose after a 20 mile highway drive and just coolant. i'm starting to believe that i'm just cursed with this truck. probably time to call in the pro's because it's starting to surpass my skill level. any last ditch effort suggestions?

 

Sounds like the heater core is plugged. Usually when there is air in a cooling system the heater only works when the rpms are up, and it stops working at idle speed.

Are you using recirculate on the hvac panel? You can blow all the heat out of the engine if it's cold enough outside and not much load on the engine.

 

i played with the re-circ door at highway speed with the air temp about +12 F. no difference. gonna check and flush the core one more time really good and hope i get lucky. i'm thinking that's gotta be it because when i first filled the system up after a coolant change and idling it to get the air out is was pretty hot. then when i started to drive it went luke warm and stayed there. i'll put a post up with the results after i'm done tinkering. wish me luck.

 

do you notice you have more heat when the heater fan speed is low? and as the fan speed is increased the heat output decreases, if so the heater core is plugged another key is the type of thermostat you installed if its an OEM style it has a plate on the bottom that redirects coolant thru the core, if you used aftermarket while you might show 170-190 on the gauge, there is not enough coolant pushed thru the heater core, infact the fan cools the heater core

here is a pic of the thermostats, OEM on the left aftermarket on the right.
downside of the oem is it does cycle up/down 10+ degrees, it will outperform the aftermarket thermo in the heater output dept.

 

I think you labeled those backwords. At least my OEM and Genuine Cummins stat look just like the one on the right.

The reason they swing is part of the design to support light and heavy cooling needs. The 3rd gen stat cracks at 190° ± 3° and isn't full open until 207°, so swing is normal.

 

ok, i pulled the core hoses and flushed it out. started the truck and let it run. temp gauge showed about 170 and was putting warm borderline hot air out. filled up the radiator let it run for about 20 minutes with the bleed screw loose to burp it. closed everything up and drove about ten miles down the highway and back to luke warm, maybe a little warmer but not by much. guess the core was blocked some but more crud got in there. time to flush the whole system. just don't wanna spend all that money on more coolant. oh well, beats having to pull the hvac out and replacing the core.

 

Do you see crud in the system while flushing and draining the coolant?

 

couldn't tell if there was crud coming out. wasn't able to see the initial output when i turned the hose on.

 

oopsy, forgot I was in the 3rd gen forum, the picture is correct for a second gen stat. the temp swings in a second gen is 10-15* will swing from 195-180 all the time, yet produce more heat than the aftermarket stat even though it stays at a constant 195.

 

I wonder if a 3rd gen stat would fit in a 2nd gen?