3.3TT Engine overheating

[Vega312]

I was driving today where all of a sudden a warning light came up displaying that my engine is overheating. I quickly pulled over and discovered that my auxiliary coolant tank was low where the dip stick was not touching the coolant. I walked to local auto store and bought Zerex coolant and filled the tank to OK mark. The engine still seems to be overheating where the gauge goes to red mark and quickly back to half. After 15 mins it does the same and at times it hovers at 65 to 70 percent mark. I am suspecting that I may have air in the system since the auxiliary coolant tank was running low but was not empty. what is strange is that that the radiator coolant cap is cold to the touch and that fan is blowing cool air. Perhaps thermostat is getting stuck preventing coolant from circulating properly and maybe pressure inside causes it to open? The coolant lines are also cold to the touch indicating that there is no circulation. I looked around and was not able to find any leaks and coolant is at the same level in the auxiliary tank. Any ideas? Is there a way to purge the air bubbles from the system. I highly doubt it's the mump on a car with 24k milles.

 

[General_Vodka]

I was driving today where all of a sudden a warning light came up displaying that my engine is overheating. I quickly pulled over and discovered that my auxiliary coolant tank was low where the dip stick was not touching the coolant. I walked to local auto store and bought Zerex coolant and filled the tank to OK mark. The engine still seems to be overheating where the gauge goes to red mark and quickly back to half. After 15 mins it does the same and at times it hovers at 65 to 70 percent mark. I am suspecting that I may have air in the system since the auxiliary coolant tank was running low. what is strange is that that the radiator coolant cap is cold to the touch and that fan is blowing cool air. Perhaps thermostat is getting stuck preventing coolant from circulating properly and perhaps pressure inside causes it to open? The coolant lines are also cold to the touch indicating that there is no circulation. I looked around and was not able to find any leaks and coolant is at the same level in the auxiliary tank. Any ideas? Is there a way to purge the air bubbles from the system. I highly doubt it's the mump on a car with 24k milles.

That doesn't sound good. You sure the 2 coolant hoses coming from the rad are cold? Your thermostat must be acting up. I had air in my system but the hoses were boiling hot as the air got pumped around. Also, the temps never dropped, only rose.

 

[Vega312]

Aftter the engine cools down I will open the radiator cap and see if there is any fluid movement in the radiator. I bit strange that the the radiator cap and intake and outake hoses were cool to the touch.

 

[JSolo]

Curious to know what the level is at the radiator itself too. Maybe snap a pic if you can.

I just topped off mine the other week in the reservoir tank. Was about halfway between F and L under a fully cold state (sat over night). I get that coolant odor after shutting off the car, but no noticeable external leaks either.

 

[nodenwire]

Ran into engine temp issues on my G80 Sport this week. Turns out the thermostat heater control circuit is faulty and the thermostat needs to be replaced. Here is the TSB for those interested: https://static.nhtsa.gov/odi/tsbs/2020/MC-10183956-0001.pdf

 

[Vega312]

Looks like the issue was caused by an air bubble or low antifreeze in the radiator. Opened the radiator cap and saw air bubbles coming out of the cooling system. The auxiliary tank still had one inch of fluid so it's a little strange. Drove to work this morning without any overheating issues.

Now just need to figure our why hot air does not always want to work...

 

[M'Kehyah]

Uhm, air bubbles can indicate a bad head or head gasket...

 

[D.J.]

Hope it's as simple as that G80 TSB.

Keep us updated when resolved

 

[General_Vodka]

Looks like the issue was caused by an air bubble or low antifreeze in the radiator. Opened the radiator cap and saw air bubbles coming out of the cooling system. The auxiliary tank still had one inch of fluid so it's a little strange. Drove to work this morning without any overheating issues.

Now just need to figure our why hot air does not always want to work...

You gotta bleed the system. That's the only way to get all the air out.

 

[Vega312]

Uhm, air bubbles can indicate a bad head or head gasket...

My engine was replaced 4k miles ago so hopefully gaskets are good. I don't really drive hard anyway

 

[D.J.]

You gotta bleed the system. That's the only way to get all the air out.

but.... how did the air get in?
Head gasket leak between combustion chamber and cooling system?

 

[Vega312]

So far no overheating issues. Torque Pro indicates my coolant temp at around 210 F. Will check coolant to make sure nothing is leaking.

 

[JSolo]

What I noticed on my 2.5T, with the level at the F mark, after engine reaching operating temp, the fluid will rise about 3/8" to 1/2" or so above the F line.

How did the air get in? I think that's simple. If/when the reservoir runs low (why is the kia system atmosphere venting to begin with!?@#), there's no more fluid to suck in as the coolant cools and contracts. Instead air is sucked in. Now air is free to circulate about within the cooling system.

tl;dr, IMO it's important to keep the res levels above L.

This is the first car i've had where I had to top off coolant in between fluid drain/fills. In the coolant smell thread, I linked to a thread on the k5 forum where an owner heard coolant gurgling sounds while driving. Turns out his res was exceptionally low.

As for correcting this, I suppose one can try one of those lisle burp funnels. They attach to the radiator at the cap fitting. You fill up the funnel ~half way. Allow the engine to warm up and fans to cycle at least twice while adding fluid to keep the funnel full.

I'd have to try this if I had the OP's issue. My method when doing a drain/fill is to use a vacuum filler (https://www.amazon.com/UView-550000-Airlift-Cooling-Checker/dp/B0002SRH5G). There's no need to burp anything or have thermostat cycle.

The OP indicated engine was replaced 4K ago. Possible they didn't bleed it properly thoroughly. IMO, it's up to the owner to keep track of fluids, esp on a new engine. Assume the mechanic putting it together is incompetent.

For you GT2 owners, does the dash indicate what the actual coolant temp is?

 

[Vega312]

That is exactly what I did - just kept adding more coolant while radiator was burping.... Looks like a design flaw on Kia's end.
I only have oil temp, torque, and Turbo Psi digital indicators.

 

[nhcowboy28]

For you GT2 owners, does the dash indicate what the actual coolant temp is?

Analog water temp.

 

[Vega312]

Looks like coolant keeps disappearing from the overflow tank and have a coolant smell inside the cabin. Dealer was not able to find a leak. Not long ago the engine warning light came up that engine was overheating and that is why I found out my coolant was disappearing. Going to pour florescent liquid into radiator to see where the leak is coming from as I am loosing hope at dealer's techs. Will also use the black light tonight to see where the leak is.

 

[Onno P]

If they did not replace the coolant via the vacuum method there are a lot of places where air bubbles might block (part of) the coolant flow. It can take quite some time, and coolant refills, to flush those bubbles out of the system.
Usually engines have a bleed valve at the highest point in the cooling system to bleed air during filling and filling has to be done very, very slowly to allow air to escape.

My 350Z engine was notorious in its time for trapped air.
Make sure when you park the car with a hot engine the expansion tank is filled to at or above FULL mark. If there is still a lot of air in the system, the volume will decrease significantly when the car cools down.

 

[Vega312]

I think I may have found where the coolant system leak is after pressure testing the system at 20 psi. It seems to be by the firewall on the passenger side. I think the coolant hose right above might be leaking.

 

[NS_Stinger]

My engine was replaced 4k miles ago so hopefully gaskets are good. I don't really drive hard anyway

Makes sense that you have a leak like that if the dealer replaced your engine under warranty. They probably didn't properly secure or tighten the hose that's leaking during the swap.

 

[Vega312]

Makes sense that you have a leak like that if the dealer replaced your engine under warranty. They probably didn't properly secure or tighten the hose that's leaking during th