Color change of engine coolant

2007 HYUNDAI MATRIX

95,000 MILES • 1.6L • 4 CYL • 2WD • MANUAL

EMAD1964

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I change engine coolant every 6 months. Last time (3 weeks ago) I changed it, though the old coolant has not been bad. However, I'd rather to not leave it more than 6 months, as my car is old. The same green coolant "Mannol G13" was added, as usual. But yesterday (after three weeks only of adding the new coolant) I found out that the coolant color has turned brownish green. I was surprised because the engine temperature has not gotten high recently.
Knowing that the oil level in engine has not reduced, and the oil itself is clear and free from water issue.
Besides, the coolant level has not increased. no exchange leakage between coolant and oil.
What could be the reason for that?

Mar 29, 2022 at 6:09 AM

JACOBANDNICKOLAS

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110,175 POSTS

Hi,

Often times that is caused by corrosion or rust in the engine. However, if you change the coolant that often, that really shouldn't be a concern.

Do me a favor, confirm the transmission fluid is full and clean. The transmission cooler likely is integral to the coolant radiator.

Please understand that this model wasn't offered in the US, so I don't have technical info specific to this, but the cooler can rupture in the radiator and cause the two to mix.

Let me know. Also, if you can get a pic of what the coolant looks like, it may help.

Take care,

Joe

Mar 29, 2022 at 7:00 PM

EMAD1964

MEMBER
17 POSTS

Thanks a lot, Joe.
I confirm that the transmission fluid is full and clean.
And I'll get some pics of engine coolant and send it to you soon.

Mar 30, 2022 at 11:03 AM

JACOBANDNICKOLAS

CERTIFIED EXPERT
110,175 POSTS

Hi,

You are very welcome. I will watch for the pics. Also, I'm glad it wasn't mixed with the transmission fluid.

Take care,

Joe

Mar 30, 2022 at 7:57 PM

EMAD1964

MEMBER
17 POSTS

Until I get the pics, I think also as long as the coolant level is constant in the coolant reservoir tank and the radiator as well that means no leak between both coolant and any other fluid. Is that correct?

Mar 31, 2022 at 5:03 AM

JACOBANDNICKOLAS

CERTIFIED EXPERT
110,175 POSTS

Hi,

That is correct. I have a feeling the best thing to do is flush the system. Although I can't understand how the cooling system could be corroded based on maintenance, anything is possible.

Let me know what I can do to help. Also, here is a link that explains how to flush the system:

https://www.2carpros.com/articles/coolant-flush-and-refill-all-cars

I will watch for your reply.

Joe

Mar 31, 2022 at 1:35 PM

EMAD1964

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17 POSTS

Knowing that my car was subjected to high temperature a year and half ago, but without harm to engine components. Yet, there were remaining residual corrosion particles on radiator internal surface.

Image (Click to enlarge)

Apr 1, 2022 at 7:31 AM

JACOBANDNICKOLAS

CERTIFIED EXPERT
110,175 POSTS

Hi,

That appears to be rust. Is the fluid itself that color? If it is, I would suggest flushing the system.

Let me know.

Joe

Apr 1, 2022 at 1:57 PM

EMAD1964

MEMBER
17 POSTS

Hi,

No, the fluid color is green.
I have a syringe full of it. I filled this syringe from the radiator now.

Image (Click to enlarge)

Apr 1, 2022 at 5:49 PM

JACOBANDNICKOLAS

CERTIFIED EXPERT
110,175 POSTS

Hi,

That actually looks really good. I would leave it alone. The next time you plan to change the fluid, simply follow the link I attached above for flushing the system.

If you have questions, let me know.

Take care,

Joe

Apr 1, 2022 at 8:19 PM

EMAD1964

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17 POSTS

Thanks a lot Joe.

Apr 2, 2022 at 6:57 AM

JACOBANDNICKOLAS

CERTIFIED EXPERT
110,175 POSTS

You are very welcome. Also, please feel free to come back anytime in the future. You are always welcome here.

Take care of yourself,

Joe

Apr 2, 2022 at 8:39 PM

EMAD1964

MEMBER
17 POSTS

I'd be happy to communicate with you any time later.
Thank you so much, Joe.

Apr 3, 2022 at 1:46 PM