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Overheating when idle after thirty minutes of driving?

Tiny
JR2244
  • MEMBER
  • 2016 HYUNDAI ACCENT
  • 1.6L
  • 4 CYL
  • 2WD
  • AUTOMATIC
  • 110,000 MILES
About a year ago, my girlfriend's car overheated, and she took it to a shop. The water pump was replaced and as well as the A/C compressor.

This year her car started to overheat when idle after driving for 30+ minutes. Before this was happening, we would notice her fan would run for a while after she shut her car off. It wasn't too long afterwards that her car started overheating.

If she turns her car off and immediately starts it again, it shows normal temp ranges. We replaced her thermostat and her Engine Coolant Temp Sensor. We don't see any coolant leaking anywhere.

I know enough about cars to get me in trouble, but not enough to know which direction to go next. Since it only happens when idle, it makes me think radiator fan, but the fan does run, like today, she got back and her fan ran for a few minutes after she turned off her car.

I am running out of ideas and am not sure what to try next. I would like to avoid going to a mechanic if we can, I am handy enough to do most repairs on my own, but I also don't want to just replace things without knowing if it is going to work. The thermostat and temp sensor were simple enough and not too expensive.

What are some other things I could check?
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Wednesday, September 20th, 2023 AT 7:17 PM

9 Replies

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 108,254 POSTS
Hi,

Will it overheat if you continue driving it at highway speeds for an extended period of time? Also, just FYI, there have been engine issues related to the cylinder heads and the engine block. To the best of my knowledge, Kia is replacing the engine for a few different reasons. For example, does the engine use excessive oil? Are there any odd sounds from the engine that may indicate a cylinder head leak or an engine bearing issue?

Do me a favor. Take a look at the technical service bulletin below and let me know your thoughts. If there are some of these issues, overheating can be a symptom.

Take care,

Joe

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Thursday, September 21st, 2023 AT 7:40 PM
Tiny
JR2244
  • MEMBER
  • 10 POSTS
I appreciate the information. We changed her oil just over 2 months ago, the oil level is low, we changed it the last week of July. I am not sure what an acceptable amount of oil loss is, but it is definitely low. Oil pressure light hasn't come on, but could the low oil level be what is causing it to overheat when idling after driving for a bit? It is right at the low mark on the dip stick.

I haven't noticed any abnormal sounds coming from the engine, but I am not entirely sure what a cylinder head leak would sound like. I will see if I can find some examples online and compare.

To update the information, I think I originally put 110,000 miles as a guestimate, but it is at 125,000. I was able to check the Odometer last night when I checked the oil level.
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Friday, September 22nd, 2023 AT 1:08 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 108,254 POSTS
Hi,
4
If the oil level is at the add mark, that indicates it is a quart low. How many miles have been put on it since the oil change? If it is less than 1000 miles, then we have an issue.

Let me know. Also, I attached information below relevant to the test.

Take care,

joe

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Friday, September 22nd, 2023 AT 1:28 PM
Tiny
JR2244
  • MEMBER
  • 10 POSTS
A little over 2,200 miles since the oil change.

Thank you for the info, I will follow those instructions and get the oil topped off, then check levels after 1,000 miles.

If her car overheats before the 1,000 miles, do you suspect it's the cylinder heads or the engine block causing the issue?
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Friday, September 22nd, 2023 AT 1:39 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 108,254 POSTS
Hi,

That is a good question. We will likely need to check engine compression to see if there is an excessive variation in one or more of the cylinders. You will need a compression tester, but most parts stores will lend one to you.

Here is a link that explains how it's done:

https://www.2carpros.com/articles/how-to-test-engine-compression

Let me know how things turn out for you.

Take care,

Joe
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Friday, September 22nd, 2023 AT 2:42 PM
Tiny
JR2244
  • MEMBER
  • 10 POSTS
Well, the car hasn't been driven much since the last reply. We have only gone about 100 miles; the oil level is still fine. So, it sounds like it is on to the compression test.

If there is an excessive variation in one or more of the cylinders, is that something that can be fixed, or is it even worth fixing? If it passes the compression test, are there any other things you can think of that could cause this?
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Monday, October 16th, 2023 AT 1:56 PM
Tiny
JACOBANDNICKOLAS
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Hi,

As far as the compression test, yes, anything can be fixed. With the vehicle being a 2016, I would feel it should have a good retail value, so certainly consider repairs. If there is damage to a cylinder wall, we may be able to fight Hyundai to have the engine replaced due to the recalls.

When you check compression, first check all 4 of them and record each reading. If you have a low cylinder, add about 1 tablespoon of engine oil to that cylinder and retest compression in that cylinder. If it goes up, then we have a piston ring or cylinder wall issue. If there is no change, then it could be related to a leaky valve or cylinder head gasket.

Let me know what you find,

Joe
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Monday, October 16th, 2023 AT 7:38 PM
Tiny
JR2244
  • MEMBER
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Compression test complete:
Cylinder 1 - 150 psi
Cylinder 2 - was between 155-160 psi
Cylinder 3 - 150 psi
Cylinder 4 - was closer to 160 psi
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Thursday, October 19th, 2023 AT 4:20 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 108,254 POSTS
Hi,

You have two cylinders under the manufacturer's minimum specifications of 156.46 psi. (See pic 1 below) I suspect that could be the issue. At this point, I would recommend contacting a Hyundai dealership and explain what is happening. Hopefully, they will do something to help.

I feel that due to an oil circulation issue (known issue see pic 2), caused the rings to wear prematurely.

Let me know your thoughts.

Take care,

Joe

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Thursday, October 19th, 2023 AT 5:51 PM

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