Read this before replacing your heater core! (Heat not blowing hot)


Latimera

New Member
Joined
Jan 17, 2021
Messages
14
Location
New Jersey
Hey everyone! So, I recently went through the process of replacing my heater core in my 06 TJ. Although it is a pretty straight forward job, it is time consuming and can be intimidating to the newer Jeeper. The last thing anyone would want is to have to it twice. Unfortunately, that is exactly what happened to me. It has also inspired me to do some research and make this write up to ensure none of you have the same problem. I’ll start by providing a little background on what happened, but if you want to skip to the fix just scroll down to the last paragraph.

My TJ had a leaky heater core, so I went to RockAuto and bought a replacement. I tore the dash apart and decided it was a good idea to replace most of the hard to get to parts in the heater box to avoid having to take it all apart again in the future. After getting her all back together I noticed the heat no longer blew hot. I then proceeded to top off the coolant and pull a vacuum to get rid of any air pockets in the system. Still Nothing. I then replaced the thermostat and thermostat gasket thinking it might be that, with no luck. I then checked all the doors on the heater box from the outside and they seemed to be functioning fine. I parked the Jeep on a steep incline hoping any air bubbles would rise to the top and come out the radiator cap, added a bit more coolant and still nothing. I then disconnected the two heater hose lines from the core in the firewall and coolant came pouring out, indicating there is no air pocket in the core. I was at a complete loss, so I went to the forums.

On the forums is where I was able to find one other person who had the same issue. He claimed that after buying a second new heater core and installing it the problem was fixed. The last thing I wanted to do was take apart the dash again, but it was starting to look like my only option. I decided to get another new core, this time from a highly recommended company called Performance Radiator. Huge shoutout to them as their customer service was great and the part was overnighted for free. After the installation of the second new core the heat blew hot once again. Now I could have stopped there, returned the faulty core, and got my 60 bucks back. However, that wasn’t going to satisfy me. I needed to know exactly what caused this so I can ensure more people don’t go through the same process that I did.

Attached are pictures of everything I will explain now. I decided to cut the stock core and the faulty new core open to see what I can find. As you can see the stock core uses metal “turbulators” to spiral the coolant and also create more surface area to heat up; therefore, making your heat blow hotter. The faulty core uses similar but SIGNIFIGANTLY flawed plastic turbulators. The OEM turbulators are made to be long, thin, and metal. This is to ensure they do not cause a blockage of coolant. The plastic ones are much larger and have much tighter spirals as you can see. The problem with this is they act as a cork and block the flow of coolant making it so coolant skips over the core and takes the path of least resistance, which is right out the exit pipe. This means there is no new hot coolant flowing through the core, which in turn gives you no, or very little heat. The important thing to note is that this is not only with my core, plastic turbulators are used in many aftermarket cores, most of which will not work once they are installed. As of now the only core I can confirm that does not use the plastic turbulators is from Performance Radiator. It is imperative to check that the core you are purchasing does not use plastic turbulators before you install. I hope this thread can help at least one person, and please feel free to ask any questions about the process as I am pretty familiar with it now!

Faulty Core.jpeg


OEM Core.jpeg


Turbulators.jpeg


Side By Side Cores.jpeg
 

Irun

Jeep Addict
Supporting Member
Joined
Oct 31, 2019
Messages
2,255
Location
Virginia
Sorry you had to do this twice, but awesome detective work. Thanks for taking the time to share!
 
  • Like
Reactions: Squatch

Sancho

TJ Addict
Supporting Member
Joined
Jan 17, 2018
Messages
1,262
Location
San Diego, CA, United States
Thanks... my performance heater core and condensor were ordered last week.

Great timing on post!


Btw... shipping isn't free.
The price is $5-7 lower when calling on phone, but they charge shipping when ordered over phone.
 

NDSpeed

TJ Enthusiast
Joined
Jul 11, 2019
Messages
877
Location
Fairbanks, AK
I recently did my heater core swap from a leaky core.

did you have any heat after the swap?

I believe I had a mixing door fail.
 

Chris

Administrator
Staff Member
Ride of the Month Winner
Joined
Sep 28, 2015
Messages
60,872
Location
Florence, AZ
Damn, thanks for doing this! This is invaluable info! I've moved it to the TJ Resources section where it belongs as it is a great resource for others.
 

Chris

Administrator
Staff Member
Ride of the Month Winner
Joined
Sep 28, 2015
Messages
60,872
Location
Florence, AZ
In case I missed it, how can you check to see if the core uses metal or plastic without cutting it open?

Also, do you have a link to the Performance Radiator core you refer to?
 

MountaineerTom

LJ Enthusiast, Retired USAF Weapons Loader
Supporting Member
Joined
Sep 25, 2018
Messages
3,102
Location
Sumter, SC
In case I missed it, how can you check to see if the core uses metal or plastic without cutting it open?

Also, do you have a link to the Performance Radiator core you refer to?

I seem to recall someone looked down in one of the tubes before and could see the plastic. I may be mistaken though.

If you had one of those endoscope camera/light things, I’d imagine you could tell.
 
  • Like
Reactions: Chris
OP
Latimera

Latimera

New Member
Joined
Jan 17, 2021
Messages
14
Location
New Jersey
I recently did my heater core swap from a leaky core.

did you have any heat after the swap?

I believe I had a mixing door fail.
After the install of the faulty core there was only room temp air blowing out. After the install of the performance radiator core the heat blew hot immediatly. You can actually check if all the doors are functioning correctly without taking apart the dash. If you’re felxible enough just look under the dash and you should be able to see all the vacuum motors and hinges. Move the climate knobs to see if they are moving freely.
 
OP
Latimera

Latimera

New Member
Joined
Jan 17, 2021
Messages
14
Location
New Jersey
In case I missed it, how can you check to see if the core uses metal or plastic without cutting it open?

Also, do you have a link to the Performance Radiator core you refer to?
Unfortunalty there is no way to tell if the core uses plastic or metal without cutting it open. I would call where ever you are planing on ordering from and ask. If they cant tell you, chances are its not a core you should be buying. And yes the core I got is this one, just make sure you get the one for you’re year/make/model!
 

Chris

Administrator
Staff Member
Ride of the Month Winner
Joined
Sep 28, 2015
Messages
60,872
Location
Florence, AZ
Unfortunalty there is no way to tell if the core uses plastic or metal without cutting it open. I would call where ever you are planing on ordering from and ask. If they cant tell you, chances are its not a core you should be buying. And yes the core I got is this one, just make sure you get the one for you’re year/make/model!

Good to know! I think you're right too. If they can't tell you if it's metal or plastic, probably shouldn't buy from them anyways. I can't believe some of that junk is made of plastic. I guess it pays to do your research.
 
OP
Latimera

Latimera

New Member
Joined
Jan 17, 2021
Messages
14
Location
New Jersey
Good to know! I think you're right too. If they can't tell you if it's metal or plastic, probably shouldn't buy from them anyways. I can't believe some of that junk is made of plastic. I guess it pays to do your research.
Yea for sure, I was very supprised to see that companies are just straight up selling non working cores. Sad to see, but hey now we know.
 

Chris

Administrator
Staff Member
Ride of the Month Winner
Joined
Sep 28, 2015
Messages
60,872
Location
Florence, AZ
Yea for sure, I was very supprised to see that companies are just straight up selling non working cores. Sad to see, but hey now we know.

And sadly most people won't find out until it's too late, creating a massive headache for themselves.

I suspect a lot of cheap crap like this could be found at Autozone or similar.
 

05Rubicon

Member
Joined
Sep 26, 2016
Messages
33
Location
Senoia, Georgia
I just went through this exact same problem with my 05 Rubicon, leaky heater core, replaced (by a shop I use because I have AC also) also replaced the AC evaporator since it was out. NO HEAT. Made sure blend door was functioning properly, no air in system, back to the shop. Pulled NEW heater core and looked inside with a scope, sure enough, it was blocked. Installed new core #2, heat works great!
 

khakitj

TJ Enthusiast
Supporting Member
Joined
Sep 2, 2019
Messages
151
Location
NorCal
Hey everyone! So, I recently went through the process of replacing my heater core in my 06 TJ. Although it is a pretty straight forward job, it is time consuming and can be intimidating to the newer Jeeper. The last thing anyone would want is to have to it twice. Unfortunately, that is exactly what happened to me. It has also inspired me to do some research and make this write up to ensure none of you have the same problem. I’ll start by providing a little background on what happened, but if you want to skip to the fix just scroll down to the last paragraph.

My TJ had a leaky heater core, so I went to RockAuto and bought a replacement. I tore the dash apart and decided it was a good idea to replace most of the hard to get to parts in the heater box to avoid having to take it all apart again in the future. After getting her all back together I noticed the heat no longer blew hot. I then proceeded to top off the coolant and pull a vacuum to get rid of any air pockets in the system. Still Nothing. I then replaced the thermostat and thermostat gasket thinking it might be that, with no luck. I then checked all the doors on the heater box from the outside and they seemed to be functioning fine. I parked the Jeep on a steep incline hoping any air bubbles would rise to the top and come out the radiator cap, added a bit more coolant and still nothing. I then disconnected the two heater hose lines from the core in the firewall and coolant came pouring out, indicating there is no air pocket in the core. I was at a complete loss, so I went to the forums.

On the forums is where I was able to find one other person who had the same issue. He claimed that after buying a second new heater core and installing it the problem was fixed. The last thing I wanted to do was take apart the dash again, but it was starting to look like my only option. I decided to get another new core, this time from a highly recommended company called Performance Radiator. Huge shoutout to them as their customer service was great and the part was overnighted for free. After the installation of the second new core the heat blew hot once again. Now I could have stopped there, returned the faulty core, and got my 60 bucks back. However, that wasn’t going to satisfy me. I needed to know exactly what caused this so I can ensure more people don’t go through the same process that I did.

Attached are pictures of everything I will explain now. I decided to cut the stock core and the faulty new core open to see what I can find. As you can see the stock core uses metal “turbulators” to spiral the coolant and also create more surface area to heat up; therefore, making your heat blow hotter. The faulty core uses similar but SIGNIFIGANTLY flawed plastic turbulators. The OEM turbulators are made to be long, thin, and metal. This is to ensure they do not cause a blockage of coolant. The plastic ones are much larger and have much tighter spirals as you can see. The problem with this is they act as a cork and block the flow of coolant making it so coolant skips over the core and takes the path of least resistance, which is right out the exit pipe. This means there is no new hot coolant flowing through the core, which in turn gives you no, or very little heat. The important thing to note is that this is not only with my core, plastic turbulators are used in many aftermarket cores, most of which will not work once they are installed. As of now the only core I can confirm that does not use the plastic turbulators is from Performance Radiator. It is imperative to check that the core you are purchasing does not use plastic turbulators before you install. I hope this thread can help at least one person, and please feel free to ask any questions about the process as I am pretty familiar with it now!

View attachment 228663

View attachment 228664

View attachment 228665

View attachment 228666

when I replaced my cooling system, I found what looked like two of those faulty turbulators sitting right behind my water pump - do you suppose they made it here all the way from the heater core?

1615009372597.jpeg
 
  • Wow
Reactions: lulzpwndyah