Cabin Heat Low

[Canadianbear]

Hello,
Over the last couple of days I've noticed my cabin heat when set to high is barely warm.
The engine temp gauge seems to be normal at operating temperatures but the cabin heat is not hot it is barely warm.

I've read several threads that it could be either: low coolant, clogged heater core or faulty thermostat. But I haven't been able to find anything on how to diagnose the actual problem
My coolant level is fine. Does anyone have any ideas on how to diagnose the problem or what I should look at other than thermostat replacement or heater core flush?

Any help is greatly appreciated.

2016 Ram 2500, 6.7L Cummins.
258,000 kms
No mods.

Thank you in advance.

 

[RamDiver]

AFAIK, your vintage of HDs are notorious for having a blocked heater core.

What is the maintenance history on the coolant system, last change or flush?

Open the rad cap when cooled, make sure the coolant level is full, check that the coolant overflow is not dry and at the correct hot or cold level.

If the level is low, look for leaks at rad seams and hoses/hose clamps.
If the level is correct, it's likely time to try back-flushing the heater core.

Many threads are covering this topic. Use the search utility in the upper right corner.

Also, read up on a coolant system treatment using RMI-25. It is available at Amazon.

RMI-25 - Engine Coolant System

Welcome to the official website of Nevada Coolant, LLC, makers of RMI-25. RMI-25 restores the additive package to your antifreeze.

www.rmi25.com

RMI-25 is far less expensive in the US, like many things. $99 US for 4 quart-sized bottles.

Amazon.com: 1 : Automotive

Buy 1: Cooling System - Amazon.com ✓ FREE DELIVERY possible on eligible purchases

www.amazon.com

$261 for the same 4 jugs up here in Canada.

Liphontcta Cooling System Treatment Gallon (4 Quart Bottles), Antifreezes & Coolants - Amazon Canada

Liphontcta Cooling System Treatment Gallon (4 Quart Bottles) in Antifreezes & Coolants.

www.amazon.ca

If you're close to the US and have access to a post box or receiving company like MyUSAddress.ca in Ogdensburg, NY, take the drive and save. I'm 40 minutes away and go regularly.

.

 

[Wild one]

Once you get heat back,you might want to look into a coolant filter.

Sinister Diesel Coolant Filter Kit w/ Wix Filter - Dodge 2013-2018

Add years of life to your 2013-2018 Dodge 6.7L Cummins diesel engine with Sinister Diesel's Coolant Filter system. Removes contaminates so that your water pump, engine oil cooler, and EGR cooler (if equipped) will last longer. This kit comes with a WIX coolant filter.

www.bcdiesel.ca

 

[Canadianbear]

AFAIK, your vintage of HDs are notorious for having a blocked heater core.

What is the maintenance history on the coolant system, last change or flush?

Open the rad cap when cooled, make sure the coolant level is full, check that the coolant overflow is not dry and at the correct hot or cold level.

If the level is low, look for leaks at rad seams and hoses/hose clamps.
If the level is correct, it's likely time to try back-flushing the heater core.

Many threads are covering this topic. Use the search utility in the upper right corner.

Also, read up on a coolant system treatment using RMI-25. It is available at Amazon.

RMI-25 - Engine Coolant System

Welcome to the official website of Nevada Coolant, LLC, makers of RMI-25. RMI-25 restores the additive package to your antifreeze.

www.rmi25.com

RMI-25 is far less expensive in the US, like many things. $99 US for 4 quart-sized bottles.

Amazon.com: 1 : Automotive

Buy 1: Cooling System - Amazon.com ✓ FREE DELIVERY possible on eligible purchases

www.amazon.com

$261 for the same 4 jugs up here in Canada.

Liphontcta Cooling System Treatment Gallon (4 Quart Bottles), Antifreezes & Coolants - Amazon Canada

Liphontcta Cooling System Treatment Gallon (4 Quart Bottles) in Antifreezes & Coolants.

www.amazon.ca

If you're close to the US and have access to a post box or receiving company like MyUSAddress.ca in Ogdensburg, NY, take the drive and save. I'm 40 minutes away and go regularly.

.

Thank you for the information. All coolant levels are looking good. it was the first thing I checked.
When doing the flush, I intend to flush with a garden hose and water first, blow the water out with compressed air and then add the RMI-25 or CLR and reflush with water and blow out.
Doing it this way, do I need to worry about air getting into the system and creating an airlock?

 

[Wild one]

Thank you for the information. All coolant levels are looking good. it was the first thing I checked.
When doing the flush, I intend to flush with a garden hose and water first, blow the water out with compressed air and then add the RMI-25 or CLR and reflush with water and blow out.
Doing it this way, do I need to worry about air getting into the system and creating an airlock?

You'd add the RMI after you've done the flush and have the cooling system all buttoned back together.Use the CLR as your flushing agent.
Don't worry about an airlock until you're done flushing the system.
There's lots of video's on You Tube showing how to flush the cooling system using CLR

Flushing A Heater Core

Come along with Eric O. at the SMA shop as we diagnose and repair this 2013 Ram 3500 Cummins that came in with a complaint of no heat out of the dash vents. ...

www.youtube.com

Google Search

 

[Canadianbear]

You'd add the RMI after you've done the flush and have the cooling system all buttoned back together.Use the CLR as your flushing agent.
Don't worry about an airlock until you're done flushing the system.
There's lots of video's on You Tube showing how to flush the cooling system using CLR

Flushing A Heater Core

Come along with Eric O. at the SMA shop as we diagnose and repair this 2013 Ram 3500 Cummins that came in with a complaint of no heat out of the dash vents. ...

www.youtube.com

Google Search

Thank you for the response and video link.
I will review and see if I have any other questions

 

[Ramez]

air water flush gun, that crud is coming from the block so unless you want do this ever year it needs flushed too, not some wimpy water hose the air/water flush will blow it out of the lower radiator hose and turn the tide on that.

 

[Burla]

Amazing you have 250k plus miles on that thing because you are ground zero for both EGR cooler debacle and casting sand, both can clog the heater core. Do a lot of long miles and avoid low rpm idle for that EGR. Good to look into additives as well keep the EGR from gumming up. They designed a system that you bought, that uses coolant to cool exhaust gas in order to reburn it, so in the past coolants just cool blocks where you aren't even cooling 1/2 of the temp your new system cools. Rams your age all have to deal with casting sand disgrace, but Cummins have an entire nother worry, EGR killing heater core plus casting sand.

 

[06 Dodge]

Amazing you have 250k plus miles on that thing because you are ground zero for both EGR cooler debacle and casting sand, both can clog the heater core. Do a lot of long miles and avoid low rpm idle for that EGR. Good to look into additives as well keep the EGR from gumming up. They designed a system that you bought, that uses coolant to cool exhaust gas in order to reburn it, so in the past coolants just cool blocks where you aren't even cooling 1/2 of the temp your new system cools. Rams your age all have to deal with casting sand disgrace, but Cummins have an entire nother worry, EGR killing heater core plus casting sand.

View attachment 577565

I guess I'm read the wrong Cummins forums, I've read about scale, lime, rust and the problems from mixing HOAT & OAT coolants an such but not sand problems...

 

[Burla]

I guess I'm read the wrong Cummins forums, I've read about scale, lime, rust and the problems from mixing HOAT & OAT coolants an such but not sand problems...

I cant post from cummins forums just Google it. I do not know how bad it is versus what we see in hemi's, but the reports are there. Of course the EGR cooler issue is well known. I think there is a fatal flaw for coolants as opposed to mixing, and I'm not even sure if changing fluid more often would help. Maybe adding a rmi-25 product would help in theory. But it is a bad design for engine longevity. I wonder how a different t stat may help.