Potential coolant problem

maltbie

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I bought a used CPO 18 Stinger GT2 last month with 47K miles from a KIA dealer. I have driven it about 2500 miles so far. I have not noticed any performance issues. The turbos spin right up when I step on the gas giving plenty of boost and there are no unusual sounds. The only mod, which came with the car, is a K&N CAI. The K&N air filters look clean. I had the dealer install new spark plugs because there was no service record of the plugs having ever been changed.

A few weeks ago I noticed a cloud of white vapor in the rear view mirror when I accelerated hard about 10 minutes into a drive. It was below freezing so I assumed it was just condensation burning off.

Yesterday, I noticed white vapor coming out of the exhaust after a 90 minute trip when I got out and watched the tail pipes while idling. The vapor did not have any obvious odor. I also checked the coolant expansion tank for the first time and noticed the level was well below the low line. I added about 13 oz. of coolant to bring it level with the low line. This morning, after the car had sat overnight, I needed to add another 2 oz. of coolant to bring it level with the low line.

I also checked the oil and noticed the level is about 1/4 inch above the F line on the dipstick. I know the KIA dealer had changed the oil right before I bought the car but I do not know whether they added any coolant. If the coolant in the expansion tank was at the low level line when I bought it, it appears the car has lost about 15 oz of coolant over the past 2500 miles of driving. I checked for leaks in the engine bay and did not see anything wet or anything with the greenish/yellow color of the coolant.

This morning I recorded the exhaust at start up after the car had been parked for 12 hours and then when the car was warmed up after some spirited driving for about 15 minutes.

At start up, there is no visible exhaust: h t t p s://drive.google.com/file/d/13RUqISHwJrOTKlFvx8fQE6c5Z8gHnRgb/view?usp=sharing (remove the spaces between h t t p s to open the link)

After the car was warmed up, you can see visible vapor coming from the tail pipes: h t t p s://drive.google.com/file/d/13R_6ko3VSmZCu5lnIbuQZ2945MOywTO2/view?usp=sharing

Does the amount of visible vapor appear normal?

I will be monitoring the coolant level to see if it drops.
 
Looks normal to me. For oil, I check when cold, it's usually shows 2 dots below the F, which is where I leave the level after an oil change (DIY). When hot, due to expansion, oil is at the F mark.

I fill mine to the top line (F), when cold. Hyundai/kia cars seem to vent more coolant than any other car i've owned. I've had to add a few oz every so often over the last 10K of ownership (since new). When adding, you really should have popped the radiator cap and topped that off first, then add coolant to the F line in the reservoir.
 
yup looks normal.
 
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This is my coolant theory when it comes to the reservoir, I believe it is too small to adequately allow for the expansion of the amount of coolant.
There fore when you fill it to the mark it allows too much in the reservoir and it blows out a little at a time, I always check mine when its up to temp...you cant trust the cold min mark at all. I have never had to add to the actual radiator but have added a few ounces to the reservoir before I learned to distrust the cold mark.
 
^^I don't agree. I've never seen the level rise more than 1.5-2" above the full mark when hot. No where near the top.

Proper level is when vehicle is fully cold. It's in the owner's manual. I've attached the relevant pages.

Owner's manual specifies cool. I prefer cold as in not driven since at least 12 hours ago.
 

Attachments

From interior to exterior to high performance - everything you need for your Stinger awaits you...
If the coolant in the expansion tank was at the low level line when I bought it, it appears the car has lost about 15 oz of coolant over the past 2500 miles of driving.
That's a BIG "if"

your first video - are you joking?
your second video - are you joking?

is this your first car?
 
It seems like the coolant is leaking/burning up. I just returned from a 300 mile trip and the coolant level in the expansion tank is 1 inch below the low line. I had raised it to the low line after the car had been sitting for 12 hours right before the trip, so to be below the line while the engine is still hot from the 150 mile drive is concerning.

The KIA shop changed the spark plugs last week. Could they have done something to cause a leak?
 
^^Your baseline is flawed. Unless you know for sure the radiator was full to the top, using reservoir level is wrong.

When coolant cools, it contracts, getting sucked back into the radiator. This process goes on until the radiator is full. My guess is your radiator was also low, and res level will continue dropping after heat cycles.
 
If you are concerned take it back to the dealer and ask them to do a leak down test on the cooling system, they can determine if anything leaks and if it does scope the cylinders and see if it truly is a head gasket....which I doubt.
I havent heard anyone having head gasket issues under normal non modded driving conditions.
Spark plugs have nothing to do with the cooling system....no connection.
 
The car has cooled down and I just checked the level in the radiator. It appears to be up to the top.

h t t p s://drive.google.com/file/d/13eHh-DxVcel2j1C44b9d9flakpqONE5T/view?usp=sharing (remove the spaces between h t t p s to open the link to the image)
h t t p s://drive.google.com/file/d/13brXjvlT_BR1M56cXIxw7iyqt5nJVyUR/view?usp=sharing

The level in the expansion tank is now at the bottom of the tank, meaning it lost approximately 15 oz. of coolant during 300 miles of driving if the radiator was full when I added the 15 oz. yesterday.

Should I add another 15 oz. to bring it back to the low line and continue driving it to see if it continues to drop now that I know the radiator is full?

I see that to change the spark plugs, the intake manifold is removed and a new gasket should be installed. Could a leaking intake manifold gasket cause a loss of coolant?

No service appointments at the dealer until Dec 18.
 
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From interior to exterior to high performance - everything you need for your Stinger awaits you...
No, if they removed the intake to replace the spark plug the only gasket that exists is to seal air from going into the intake and not through the turbos and air filter system...if it was leaking you would know by rough idle (vacuum leak) and bad turbo performance (pressure leak) at idle its under vacuum and when boost hits its under pressure......none of your symptoms have anything to do with spark plug replacement unless they did it with a jackhammer lol
 
Losing that much coolant with the limited miles you've driven is not normal, for any car.
If everything is working properly, you shouldn't have to add anything after a 300 mile drive, with any car, not just the Stinger.
If you can't get it into the dealer right away, find an indie shop that can do a leak and pressure test. You can also test the coolant for traces of exhaust gas. If it's positive, it might indicate a head gasket failure.
 
If you are concerned take it back to the dealer and ask them to do a leak down test on the cooling system, they can determine if anything leaks and if it does scope the cylinders and see if it truly is a head gasket....which I doubt.
I havent heard anyone having head gasket issues under normal non modded driving conditions.
Spark plugs have nothing to do with the cooling system....no connection.
Paying for a leak down test is a lot pre-mature in this case.
 
Should I add another 15 oz. to bring it back to the low line and continue driving it to see if it continues to drop now that I know the radiator is full?
You should fill it correctly to the FULL line, and monitor.
Why would you fill it to the low line?
 
What kind of coolant do you guys use for the stinger? I don't have a lot of experience with cars. Thanks
 
From interior to exterior to high performance - everything you need for your Stinger awaits you...
I performed an engine combustion leak detector test on the expansion tank this morning. The test did not detect a combustion leak.
 
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I performed an engine combustion leak detector test on the expansion tank this morning. The test did not detect a combustion leak.
your "symptoms" were not conducive to to a combustion leak - so those results should be expected.

Now you have the test results to confirm :thumbup:

All is well.

Kia service manual says you need to check the coolant overflow level AT LEAST monthly.

Screenshot_20231207_093929_Drive.webp
 
Udpate: After performing the engine combustion leak detector test and filling the coolant to the top of the radiator and to the full line on the expansion tank 2 weeks ago, I have been monitoring the coolant level. I have driven about 1,000 miles over the past 2 weeks. I have not seen the coolant drop below the full line when the engine is cold, so either the leak is gone or the car was sold to me short a quart of coolant. That's the good news.

The bad news is that over the past 2 weeks, I have noticed a rough idle, where the tach flutters between 500 to 800 RPMs when the car is in Park. When it drops to 500, the engine sounds like it will stall and then it shakes and the RPMs flutter back up to 800. This happens after the engine has been warmed up. At a cold start, the engine has shaken and sounded very rough. I didn't notice any of this roughness before the spark plugs were changed.

This morning, the check engine light came on, and stayed on, immediately after starting the engine. I drove it to the Kia dealer this morning and asked the service department to diagnose the problem. Luckily, today was the day that I had scheduled 3 weeks ago to have them explore the coolant issue.
 
The bad news is that over the past 2 weeks, I have noticed a rough idle, where the tach flutters between 500 to 800 RPMs when the car is in Park. When it drops to 500, the engine sounds like it will stall and then it shakes and the RPMs flutter back up to 800. This happens after the engine has been warmed up. At a cold start, the engine has shaken and sounded very rough. I didn't notice any of this roughness before the spark plugs were changed.

This morning, the check engine light came on, and stayed on, immediately after starting the engine. I drove it to the Kia dealer this morning and asked the service department to diagnose the problem. Luckily, today was the day that I had scheduled 3 weeks ago to have them explore the coolant issue.
sounds like it's spark related - especially if started right when you had the plugs changed. (who changed them? you? dealer? or private mechanic?)

Keep us updated with your coolant situation... I predict the dealer will conclude - NFF (no fault found)
 
The Kia dealer performed the spark plug change about 3 weeks ago. Since then, I've driven about 1,500 miles. I've driven the car about 4,000 miles since I bought it in late October.

Today was the first day the check engine light came on although I've been noticing the rough idle since 2 weeks ago.
 
From interior to exterior to high performance - everything you need for your Stinger awaits you...
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