Engine Replacement, The Full Story.

[G70LEbyAdoom]

Soooo...I have a 2018 GT2 with 136,000 miles on it and I have been trying to diagnose this exact same issue. I bought this car new and have zero mods. The problem has not been present until this winter. The only change is, I updated the infotainment system over the summer. Has KIA corporate shared any of their findings? Would love to get this fixed but I'm not interested in a DIY engine swap or a $17k dealership swap.

Nope. They have been silent on the issue unfortunately.

 

[SafetyStinger]

Just did a quick test on my heater and at normal idle RPM I have no heat. At 800 to 900 RPM the heat comes back pretty quickly. My antifreeze levels are perfect and I don't see any leaks. Does anyone know if the heater core has a vacuum control valve or is it electronic?

 

[G70LEbyAdoom]

Just did a quick test on my head and at normal idle RPM I have no heat. At 800 to 900 RPM the heat comes back pretty quickly. My antifreeze levels are perfect and I don't see any leaks. Does anyone know if the heater core has a vacuum control valve or is it electronic?

Hopefully your thermostat has just gone bad.

 

[Hawk853]

The thermostats are electronic and pretty complex. They react to throttle position and all sorts of variables. Not at all what I’m used to with a simple bi metallic valve.

Bleeding the system is a chore. Took quite a few attempts after reinstalling my engine and needed the KDS scanner to open the valves, kind of like bleeding an ABS valve body.

I could see if one signal or piece of logic is out of whack, the thermostat motor could close, stopping coolant flow to the core.

I normally refrain from “shoot from the hip” speculation, but have been caught of guard by how difficult some troubleshooting can be due to the complexity of this car’s systems.

 

[SafetyStinger]

Yeah I'm not convinced the heater issue is caused by the thermostat. Any issues I've had with other cars and thermostats, have reacted exactly opposite to what I'm experiencing with the Stinger. (No heat at high RPM's and heat only when idle.) The main difference between heat and no heat in the Stinger is roughly 200 - 300 RPM. Is that enough of change in water pressure to push past a faulty thermostat if that isthe culprit? Or is there some vacuum actuator somewhere that is failing and requiring more vacuum than what can be produced at idle. Trying to see if I can find a schematic somewhere to see the routing for cooling system and ultimately what controls coolant flow into the heater core.

 

[SafetyStinger]

So after an exhaustive search. I believe the most likely source of this issue is air pockets in the cooling system. I don't know how or when they got there but this seems to be a common issue across several KIA models and even in the Genesis line as well. I'm going to look for an effective way to burp the coolant system and cross my fingers that it works.

 

[JSolo]

@Hawk853 What about vacuum filling the coolant?

 

[SRV]

So after an exhaustive search. I believe the most likely source of this issue is air pockets in the cooling system. I don't know how or when they got there but this seems to be a common issue across several KIA models and even in the Genesis line as well. I'm going to look for an effective way to burp the coolant system and cross my fingers that it works.

Not sure this will work here but...

To burp our Porsche 928's which has a 5.0 L v8 in the front, we jack the front of the car up, and run the engine until hot with the coolant recovery cap off, and it'll self burp. You can see the air pockets bubbling up thru the coolant tank.

BIG relief on that next drive and temps are normal again!

 

[Hawk853]

@Hawk853 What about vacuum filling the coolant?

We were using vacuum. Took 4 attempts before the computer was happy and then 2 extra to be safe. Used vacuum and to make it easier lifted the front of the car since the E thermostat is situated higher than the fill port back by the firewall.

 

[SafetyStinger]

Thanks all. I'll report back on the progress later this week. Hopefully this is a solution. The car has been pretty solid for most of the 137k miles but this could be one of those issues that makes me move on from it if I can't get it figured out.

 

[Devin]

Whatever happened to jiggle valves?

 

[JSolo]

We were using vacuum. Took 4 attempts before the computer was happy and then 2 extra to be safe. Used vacuum and to make it easier lifted the front of the car since the E thermostat is situated higher than the fill port back by the firewall.

Huh? Fill port by the firewall? Aren't you filling through the radiator neck? That's where I've always installed the vacuum filler (uview 55000).

 

[Hawk853]

Huh? Fill port by the firewall? Aren't you filling through the radiator neck? That's where I've always installed the vacuum filler (uview 55000).

The Thermostat is by the fire wall and is higher than the fill port.

 

[SafetyStinger]

Well, I thought I had this mystery solved but I'm back to no heat at idle. However, I've added another layer of intrigue to my quandary.

I pulled the car onto a make make shift ramp that raised that raised the front of the vehicle about 7 inches. With in a few minutes heat began to flow from the vents. I popped the hood and opened the overflow reservoir to see if I could see air bubbling out of the coolant system. No bubbles but I let the car run elevated on the ramp for about 45 minutes to an hour. Still blowing hot air from the vents so a back the car of of the ramp. Still blowing hot air so I parked it in the drive and shut off the engine and went inside. After 30 - 45 minutes came back out and started the car. The engine temp was still showing to be close to operating temp but no hot air coming from the vents. Went for a drive to see if I could get heat while in motion (like it has been doing). No heat. Drive for 15 minutes...no heat. I'm going to let it cool completely over night and see what I get in the morning. My next attempt will be a coolant flush and vacuum fill. Stay tuned for the next installment of "Where's my heat!"

 

[Ohiocruiser]

Well, I thought I had this mystery solved but I'm back to no heat at idle. However, I've added another layer of intrigue to my quandary.

I pulled the car onto a make make shift ramp that raised that raised the front of the vehicle about 7 inches. With in a few minutes heat began to flow from the vents. I popped the hood and opened the overflow reservoir to see if I could see air bubbling out of the coolant system. No bubbles but I let the car run elevated on the ramp for about 45 minutes to an hour. Still blowing hot air from the vents so a back the car of of the ramp. Still blowing hot air so I parked it in the drive and shut off the engine and went inside. After 30 - 45 minutes came back out and started the car. The engine temp was still showing to be close to operating temp but no hot air coming from the vents. Went for a drive to see if I could get heat while in motion (like it has been doing). No heat. Drive for 15 minutes...no heat. I'm going to let it cool completely over night and see what I get in the morning. My next attempt will be a coolant flush and vacuum fill. Stay tuned for the next installment of "Where's my heat!"

It does look like you have air in the system. Here's how i bleed mine after i replaced leaking radiator. I used radiator funnel kit. Raised the front of the car. Install the funnel to radiator and started the car. Turned the heater to the max and kept it running until the engine warmed up, around 20-30 min. Also was making sure the funnel didn't go empty. Kept it at around half full. Worked just fine. Not sure if vacuum fill will do the trick, since the thermostat has to be open to completely fill the system. And manual requires kds tool, so you can open thermostat without waiting for engine to warm up.

 

[JSolo]

Wonder how all this applies to the 4 banger? Probably similar.....? I've used vacuum filler on the last few cars - g37, '15 accord 4 cyl, and an older grand prix with the 6 (early 2000's model). The vacuum filler has worked well for drain/fills.

In fact, other than the contents of the radiator, how much of the rest of the system actually drains? I usually do a drain/fill around year 4-5, so we'll see.

Edit: A tell tale sign of air in the system is a sloshing sound when making turns.

 

[SafetyStinger]

It does look like you have air in the system. Here's how i bleed mine after i replaced leaking radiator. I used radiator funnel kit. Raised the front of the car. Install the funnel to radiator and started the car. Turned the heater to the max and kept it running until the engine warmed up, around 20-30 min. Also was making sure the funnel didn't go empty. Kept it at around half full. Worked just fine. Not sure if vacuum fill will do the trick, since the thermostat has to be open to completely fill the system. And manual requires kds tool, so you can open thermostat without waiting for engine to warm up.View attachment 77543

Thanks for sharing this. Seems like a worthwhile investment to not have to deal with this aggravation in the future.