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6.0L Power Stroke Diesel 2003 - 2007 F250, F350 pickup and F350+ Cab Chassis, 2003 - 2005 Excursion and 2003 - 2009 van

Heater is barely heating

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Old Nov 25, 2016 | 11:52 AM
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Heater is barely heating

Not sure if my heater was ever strong or not, just bought the truck this fall. Got a 200° thermostat and the engine runs 200-205° Cab heater works, but barely. Not enough heat to keep me dogs warm now that temps are dropping. Of course I live in Portland Oregon so temps here are still only 40's

Any ideas what to test or check?
 
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Old Nov 25, 2016 | 11:53 AM
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Blend door
 
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Old Nov 25, 2016 | 11:54 AM
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Nice. THanks.
 
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Old Nov 25, 2016 | 12:12 PM
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Also check the vacuum line to the coolant control valve next to the oil cap. It has a bad habit of getting knocked off.
 
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Old Nov 25, 2016 | 02:43 PM
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I would also add to the list if you check the other things and are still not getting heat.
Flow through the heater core. It could be gunked up and need a back flush.

That said I would do all the other things first.
Also if a coolant system flush was done and the heater core was not back flushed
at that time you might need to do that now.


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Old Nov 25, 2016 | 08:09 PM
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I did a hose water flush when I swapped engines, didn't back flush anything like I should've but also didn't chemical flush either. So, yeah it might need a flush.
 
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Old Dec 7, 2016 | 02:45 PM
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Okay I tested the blend door actuator and it's working, also the blend door axle and it appears and sounds like it's working. Vacuum line by oil cap intact.

I guess only thing left is heater core? Bummer.
 
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Old Dec 7, 2016 | 02:49 PM
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Did you try un hooking BOTH heater hoses and running water through just the heater core? Do a reverse flush on it with a garden hose and see what comes out.
 
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Old Dec 7, 2016 | 03:05 PM
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Us the heater valve actually working, the one installed in the hose and you applied vacuum to it for the test?
 
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Old Dec 7, 2016 | 03:06 PM
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I didn't see a valve in the hose. Where is it?
 
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Old Dec 7, 2016 | 03:06 PM
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The vac line by oil cap goes to Ac
 
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Old Dec 7, 2016 | 05:38 PM
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Here's the valve. By default (no vacuum applied) it will allow coolant to pass.

After the coolant temp is up, feel the 2 rubber hoses coming from the core to see if they're hot showing circulation.
 
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Old Dec 7, 2016 | 06:13 PM
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Well, that's odd. I don't have one of those!
 
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Old Dec 7, 2016 | 06:42 PM
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Are the heater hoses feeding the core at least hot?
 
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Old Dec 7, 2016 | 06:47 PM
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I haven't felt them as 87crew dually suggests. I'll do that tomorrow.
I didn't flush the core seperately either. Just left unhooked while doing the engine swap. The heater core presumably has 335k miles on it now, and 332k were heavily abused by others so I wouldn't be surprised if it needs a flush or a replace.

I was hoping to delay a full flush as I didn't want to loose my fancy coolant that is almost new, but do you think the chemical flushing agents are important for anheater core flush also? I suppose I could re use most of my coolant if I can capture it well enough. And I suppose I could just do a core flush without losing much coolant.
 
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