Heater Issue

[Alan Reagan]

Since my water pump was replaced under the recall, the heater seems to stay on the cool side unless I set the temp up to about 78. I'm going to check the vent this afternoon thinking that the tech may not have "burped" the system after the pump change. I checked the water temp coming to work this morning and it was steady at 190. Occasionally, it seems like there is a heat surge in the vents when I come to a stop. That's why I'm thinking there is air in the system.

Anything else I need to check. Blend doors seem fine. AC follows temp settings without any issue. It's only the heat that is giving me an issue.

 

[Cummins12V98]

Have you physically checked the fluid level?

 

[Alan Reagan]

Yessir, the fluid level was the first thing I looked at. I didn't want to pull the vent plug while I was on a trip just in case something went wrong. Fluid level is fine and the engine temperature is fine as well. I will check the coolant vent this afternoon to see if there is any air in the system.

 

[Alan Reagan]

On the drive home, I saw the temperature fluctuating between 170 and 195. Outside temp was 66. It’s looking like the thermostat may be sticking or is partially stuck open. That would probably explain why I’m getting sudden rushes of heat through the vents. Reservoir is full. I cranked it up after checking everything and the temp got up to 190 with me doing a high idle but dropped as soon as I let off the accelerator. I’ll change the stat. Looks like on the 2015 I can do it without removing the crossover. Hope so anyway. That will make it a fairly quick job.

 

[Alan Reagan]

Maybe a final update. My truck doesn't have the hex coolant vent. There is a sensor there now. After looking at everything again yesterday afternoon, I removed the reservoir cap and ran the truck up to temp and let it stay on high idle for about 5 minutes. Temperature was at 190. The heater started working like it should. This morning, I drove to work and the temp went to 190 and stayed steady. The heater worked. Nothing other than normal fluctuations in the temperature. So there must have been some air trapped somewhere in the system. I will pick up a new thermostat today in case the temp starts fluctuating again but for now, everything seems fine.

 

[Cummins12V98]

I was going to say the 15's have no need to be vented. Check the truck with it cold again.

 

[CBari]

I just had to replace my heater core in my 13 as it was completely stopped up. I never added any antifreeze only about a gallon of distilled water over the 5 years of ownership.

 

[Alan Reagan]

Everything seems to be normal now. Heat is good. Temperature is stable and I haven't replaced the T-stat. When I picked up the T-Stat at the shop in Macon, we talked about what was going on and they said that they had a truck in with a similar problem and there seemed to be air trapped in the heater core somehow. I can't explain it and neither could they. But both trucks have heat now.