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Color change of engine coolant

Tiny
EMAD1964
  • MEMBER
  • 2007 HYUNDAI MATRIX
  • 1.6L
  • 4 CYL
  • 2WD
  • MANUAL
  • 95,000 MILES
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?
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Tuesday, March 29th, 2022 AT 6:09 AM

12 Replies

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,867 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
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Tuesday, March 29th, 2022 AT 7:00 PM
Tiny
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.
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Wednesday, March 30th, 2022 AT 11:03 AM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,867 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
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Wednesday, March 30th, 2022 AT 7:57 PM
Tiny
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?
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Thursday, March 31st, 2022 AT 5:03 AM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,867 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

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Thursday, March 31st, 2022 AT 1:35 PM
Tiny
EMAD1964
  • MEMBER
  • 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.
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Friday, April 1st, 2022 AT 7:31 AM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,867 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
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Friday, April 1st, 2022 AT 1:57 PM
Tiny
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.
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Friday, April 1st, 2022 AT 5:49 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,867 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
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Friday, April 1st, 2022 AT 8:19 PM
Tiny
EMAD1964
  • MEMBER
  • 17 POSTS
Thanks a lot Joe.
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Saturday, April 2nd, 2022 AT 6:57 AM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,867 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
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Saturday, April 2nd, 2022 AT 8:39 PM
Tiny
EMAD1964
  • MEMBER
  • 17 POSTS
I'd be happy to communicate with you any time later.
Thank you so much, Joe.
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Sunday, April 3rd, 2022 AT 1:46 PM

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