21 duramax 3500

[Rhodesie]

bought this denali in dec of 20. within the first year i had the def tank replaced(bad heater). dropped off at 7am and called by 10 saying it was ready. awesome. kinda noticed that the heat on the drivers side of the truck never really was spectacular but don't use truck much. 26900 kms now.
anywho, now there is no heat hardly at all on the drivers side and pass side is still pretty warm but not smokin' hot. sounds like the heater core is plugged with casting sand because the engine was never completely cleaned properly. heater core is 167 bucks and the job is 3500.00. i have ext warranty so 100 it will cost me. i am curious if anyone else has run into this issue. apparently 2021 was a bad year for this.

 

[sirkdev]

This was very common on 6.0L fords back in day sand in JW would plug oil cooler and problems would start piling up from high oil temps. I would be checking your other coolers in the same system for temp drops and possible issues. After they resolve this.. look at a coolant filter. sucks..

 

[cdnredneck_t3]

bought this denali in dec of 20. within the first year i had the def tank replaced(bad heater). dropped off at 7am and called by 10 saying it was ready. awesome. kinda noticed that the heat on the drivers side of the truck never really was spectacular but don't use truck much. 26900 kms now.
anywho, now there is no heat hardly at all on the drivers side and pass side is still pretty warm but not smokin' hot. sounds like the heater core is plugged with casting sand because the engine was never completely cleaned properly. heater core is 167 bucks and the job is 3500.00. i have ext warranty so 100 it will cost me. i am curious if anyone else has run into this issue. apparently 2021 was a bad year for this.

My brother's 20 is doing the same thing. I think he's taking it to Murray's in the Hat too.

 

[Rhodesie]

My brother's 20 is doing the same thing. I think he's taking it to Murray's in the Hat too.

made it as far as irvine on saturday and turned around. BRRRRR!!

 

[JMCX]

I have a buddy with the same generation. He has poor cab heat as well. Maybe a garden hose could be hooked up and the core reverse flushed.

 

[DRD]

Would have thought both sides would be the same temp with a plugged core? My Yukon does this once in a while, blend door actuator loses it position and defaults to a position that is too hot in summer and too cold in winter. On the older units turning the control to auto and then starting/stopping the engine will make it cycle and find it's home. Newer stuff might be different...

 

[Cableguy]

i have 21 with 56k on it no prob like that so far

 

[drew562]

Would have thought both sides would be the same temp with a plugged core? My Yukon does this once in a while, blend door actuator loses it position and defaults to a position that is too hot in summer and too cold in winter. On the older units turning the control to auto and then starting/stopping the engine will make it cycle and find it's home. Newer stuff might be different...

That’s what it sounded like to me when I read it. A blend switch of sorts not working

 

[Stevemtb]

Like DRD said it sounds like blend door actuator if you have different temps on each side. My truck is doing the same thing in this extreme cold. Now that it’s warmer I’m going to try what they recommend in here (pull fuses etc to recalibrate the blend doors).

2014 Silverado blowing hot air out of passenger side and cold on driver side?

It’s odd that one day my A/C works fine and the other it blows hot to the max air out of the passenger side and cold to the max on the driver side. Defroster isn’t working properly either because when I have it on it just blows air out of the regular vents. Took it to the dealer and they say it c...

www.gm-trucks.com

 

[Rhodesie]

I hope its an easier fix. I really dislike the idea of the whole interior being pulled out of my truck.

 

[Frankenytro]

The owner of my company has a 23 Sierra Denali 6.6 that he noticed had no head on the drivers side but good heat on the passenger side this past Friday. Brought it in the Wolfe GMC and they called a heater core. I couldn’t understand the call as the passenger side was still HOT. I suspected blend air doors/actuators. It is under warranty so they are getting the job and we will see how it is when it is done. Truck was in their shop Friday afternoon to be ready for the tech to start on it Monday morning. we have been told the truck should be completed by end of day Wednesday…. That’s a big project if you are booking 3 days for a heater core, so maybe the labour cost is not too far out to lunch?

On the other hand we have done a handful of Dodge heater cores (also notorious for plugging up) and they can be done in a day as long as you put the right tech on it and that tech removes parts in modules rather than piece by piece.

 

[Rhodesie]

confirmed. everything is working normal but no heat. they tried a flush to no avail. heater core. should be done friday. 100 deductable on extended warranty.

 

[tex78]

Common thing unfortunately


If flushing the core don't get it , obviously needs replaced

There the temp doors are , the core tends to get plugged on the drivers side , hence the lower Temps

Sent from my SM-G991W using Tapatalk

 

[Frankenytro]

The boss man picked his unit up this morning. New heater core and temps as they should be.

Didn’t make sense at first, but I can see how one side could plug up and loose the ability to transfer heat.

Tex78, what does this job book at for a typical denali with full console?

 

[Rhodesie]

hope i don't end up with a squeaky rattle trap when its done.
they have a new ultimate maybe i will have to look at.

 

[tex78]

The boss man picked his unit up this morning. New heater core and temps as they should be.

Didn’t make sense at first, but I can see how one side could plug up and loose the ability to transfer heat.

Tex78, what does this job book at for a typical denali with full console?

Ya the temp doors are 2 halfs if you want to call it that , independent and split in the middle of the core area



Uhhhhhhh it's ugly ugly , hours and hours to do , 2 days , maybe less if you have done a few

Warranty pays a day lmfao

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[Rhodesie]

Ya the temp doors are 2 halfs if you want to call it that , independent and split in the middle of the core area



Uhhhhhhh it's ugly ugly , hours and hours to do , 2 days , maybe less if you have done a few

Warranty pays a day lmfao

Sent from my SM-G991W using Tapatalk

and the tech gets the shaft. so stupid.

 

[tex78]

and the tech gets the shaft. so stupid.

Totally, blunt end of the shaft yes

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[Rhodesie]

i was going to call and talk to the tech and let him know if he takes his time and does a good job that what flat rate doesn't cover in his hours i would pick up the rest. then he won't have to rush.

 

[Cableguy]

Common thing unfortunately


If flushing the core don't get it , obviously needs replaced

There the temp doors are , the core tends to get plugged on the drivers side , hence the lower Temps

Sent from my SM-G991W using Tapatalk

how common
mileage probability or age prone