Low heat?
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More Turbo
Joined: May 2018
Posts: 729
Likes: 147
From: Butler, OK
Low heat?
Ok...i know, a 5 degree high day is not really my benchmark... however, 5 people in the truck putting out hay tonight, truck ran a solid 4 hours, easily got to temp, and drove somewhere between 80 and 100 miles..... never had to turn the heat down. So, has anyone had this issue? How to fix it? The only thing ive done to the heater would be the manual valve i close in the summer, for cooler ac. And the valve has been open for a couple months now.
Lead Driver
Joined: Oct 2005
Posts: 6,129
Likes: 1,919
From: Ponca City, OK
100% sure no air pockets trapped in the core? How's the air flow from the vents? Has the blower been replaced w/ something other than factory? Might want to check the fresh air vent actuator is hooked up and operating correctly. It's the one tucked up under the dash in the passenger foot well. Could also check the core for dirt and gunk buildup on the fins. Do you have any aftermarket temp gauge, oil or water, for a real and accurate temp reading? 5 degrees ambient is pretty cold, at least to this Okie fat boy.
Fleet Owner
Joined: Jun 2004
Posts: 25,090
Likes: 1,112
From: Rio Rico, AZ.
Stepper motor for the blend door may have failed and not operating correctly. It's mounted up on top of the blend door assembly on the climate control housing. Easy access if you remove the glove box.
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More Turbo
Joined: May 2018
Posts: 729
Likes: 147
From: Butler, OK
Fan/air movement seems good i havent checked a couple of those things.... air pocket, i thought those would work out over time? How would i know? It is blowing warm air, but thats it, it never got hot. 5 degrees was our high yesterday, over here on the west side of okie land. And i was putting hay out after dark... so🤷🏻.
Logistics Pro
Joined: Aug 2009
Posts: 3,609
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From: Arizona
How are you determining your coolant temp, with the factory gauge? The factory gauge is stepped but I don't know what temperature it sees when it rises to the operating range. When I had my 6.9 I experienced what you describe and had to put cardboard in front of the radiator to get enough heat while in the mountains because my thermostat was stuck open..The factory gauge would rise into the operating range but it was not very hot at all. A simple test is to get it up to temp then check radiator with a laser thermometer.
More Turbo
Joined: Aug 2021
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A month ago at deer camp, temps were low teens at night. My oil temp never got over 140 while doing the half hour ride to where I hunt. It takes a lot to keep 15 quarts of oil and 8 gallons of coolant warm. 8 hours later in the early am, oil was still upper 03's to low 40's.
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Hotshot
Joined: Mar 2014
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From: Douglassville, PA
If you ever have your cooling system drained down, remove the heater hoses and gently run water backwards through the core. It can't take a lot of pressure so take it easy. If you catch the water that comes out, you might be surprised as to how much debris comes out. Also, Sous has a good video on cleaning the fins on the core to help with circulation. I think the air coming out should still be pretty hot, regardless of how cold it is. That's all in addition to what the other guys have suggested.
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Lead Driver
Joined: Oct 2005
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From: Ponca City, OK
If the engine is getting good and warm then the heat should be too. If not then something is either restricting coolant flow through the core, or air flow over the core.
Hotshot
Joined: Dec 2005
Posts: 10,253
Likes: 7,687
From: Chino Valley, Arizona
I had the same thing until last week.
if I ran the fan on low you could feel heat but never get the cab warm, run on high and the air was cool.
replaced heater core and heater hoses and yesterday driving to town I shut the heater off after 5 miles. the water passages were clogged enough that the cold air in the cab totally cooled the small amount of water passing through the core
less than an hour to change the core.
I had a fleet of over 50 powerstroks that I maintained and have never seen an air locked heater core.
if I ran the fan on low you could feel heat but never get the cab warm, run on high and the air was cool.
replaced heater core and heater hoses and yesterday driving to town I shut the heater off after 5 miles. the water passages were clogged enough that the cold air in the cab totally cooled the small amount of water passing through the core
less than an hour to change the core.
I had a fleet of over 50 powerstroks that I maintained and have never seen an air locked heater core.
Thread Starter
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More Turbo
Joined: May 2018
Posts: 729
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From: Butler, OK
Well thats just icky.... i figured, because i cleaned my coolant system with a hose, through the heater core, 8 times...... that id could rule out that issue...but i also didnt understand how it was built.... considering age, and the heinous condition that was my coolant system before this past summer.... yeah, im gonna bet thats my issue.
That actually reminds me, i probably need to change my coolant filter, soonish....
That actually reminds me, i probably need to change my coolant filter, soonish....
Hotshot
Joined: Mar 2014
Posts: 10,750
Likes: 1,065
From: Douglassville, PA
One way to tell condition of heater core is to grab both hoses, inlet and outlet. The inlet hose should be too hot to hold and the outlet hose should be cooler. Still warm but a noticeable difference. If it's cold, your heater core is clogged.
FTE Chapter Leader
Joined: Jan 2005
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From: Henderson, NV
What was the truck's duty cycle during the activity? A 7.3 that is merely idling most of the time can actually get cold in winter weather, even if the automatic hi-idle kicks in.