Overheating, I have replaced the water pump, thermostat, and radiator cap

2005 HONDA CIVIC
199,850 MILES • 1.7L • 4 CYL • 2WD • AUTOMATIC
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JAS0822
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  • 74 POSTS
So, I have replaced the water pump, thermostat, and radiator cap. The cooling system pressure drops maybe a pound after 5 minutes, no visible leaks, but it's losing coolant. Like I run my car for 20 minutes in idle, let it cool down, take the cap off, I can’t see anything. I don’t know if I’m supposed to be able to see anything. The reservoir sounds like something’s in it, but the plastic is too cloudy for me to see. Any ideas?
Jun 28, 2022 at 1:19 PM
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STRAILER
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When the engine is overheating can you hear the cooling fans running? It sounds like you may have a blown head gasket, this guide should be able to help you confirm the failure:

https://www.2carpros.com/articles/head-gasket-blown-test

and

https://www.2carpros.com/articles/engine-overheating-or-running-hot

Please remove the oil fill cap to see if there is any whitish grey sludge on the underside of the oil cap. Please run down these guides and report back.
Jun 29, 2022 at 10:32 AM
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JAS0822
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  • 74 POSTS
Oil looks fine, and I did a radiator compression test and it came back perfect, so I don’t think it’s the head gasket.
Jun 29, 2022 at 10:39 AM
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JAS0822
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  • 74 POSTS
I also just got my cylinder compression tested, and all of them came back within spec.
Jun 30, 2022 at 8:13 AM
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STRAILER
  • ✓Experienced Mechanic
  • 55,273 POSTS
Is the cooling fan on when the engine is hot? Also, we need to do a chemical check for the head gasket, you can rent the kit at the parts store for cheap. Here is the kit on Amazon for $36.00:

https://amzn.to/3OxU2DA

Check out the diagrams (below). Please let us know what happens.

Jul 1, 2022 at 3:02 AM
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