Coolant pressure high

Tiny
ALI HOTEIT
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  • 1997 MERCEDES BENZ E280
  • 2.8L
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 180,000 MILES
The water hose pressure is very high also when the car cooled.
This pressure affects the water reservoir (changed) some water hoses changed because of leak.
Thursday, November 7th, 2019 AT 5:10 AM

10 Replies

Tiny
JACOBANDNICKOLAS
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HI:

It is normal for the cooling system to pressurize when it is at operating temp. The radiator cap is designed to release pressure at a specific point. Have you had it checked or replaced it?

Let me know.

Joe
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Friday, November 8th, 2019 AT 4:19 PM
Tiny
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Yes, I replaced it the same problem.
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Saturday, November 9th, 2019 AT 5:12 AM
Tiny
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The pressure remains high also when the car is cold (at morning).
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Saturday, November 9th, 2019 AT 5:14 AM
Tiny
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Hi:

It should release slowly as the temperature drops. Have you tried a new cap? Also, is there any chance of a bad head gasket allowing compressed air to enter the cooling system?

Here is a link that explains how to check for a head gasket issue. If you page down, it shows how to check the cooling system for evidence.

Let me know.

Joe
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Saturday, November 9th, 2019 AT 9:52 PM
Tiny
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I tried to search if it is a head gasket issue, there is no symptoms.
I uploaded the video what is happening.
Note: that this video is at very morning after a stop all night.
*I have changed most of the hoses and a side of the radiator and the cap.
Thanks for your reply
Video (Click to make bigger)
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Tuesday, November 19th, 2019 AT 5:03 AM
Tiny
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That doesn't make sense. You are certain the engine isn't building pressure via a head gasket? I ask because coolant expands when it gets hot. That is what pressurizes the system. If it exceeds a specific pressure, it is released via the cap. Now, the cap will maintain pressure below its threshold; however, under normal conditions, pressure is gone when the coolant cools and is no longer expanded. That leaves one thing. Air is getting into the system. If you remove the radiator cap when the engine is cold and start it, is there any evidence of bubbles? If you start the engine, does coolant want to come out?

I forgot to include this link in the last post.

https://www.2carpros.com/articles/head-gasket-blown-test
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Tuesday, November 19th, 2019 AT 5:33 PM
Tiny
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Thank you very much.
I will search for bubbles next morning.
In vase there is no bubbles can I use a coolant system leak repair as shown in the picture or will harm the engine?
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Wednesday, November 20th, 2019 AT 6:31 AM
Tiny
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Hi,

I never recommend using these products unless it's an emergency. Also, the problem isn't a leak but the opposite, pressure isn't releasing. Is coolant leaking at some point?

Joe
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Wednesday, November 20th, 2019 AT 2:49 PM
Tiny
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Now yes at very high pressure it is leaking from the other side of the radiator.
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Thursday, November 21st, 2019 AT 4:53 AM
Tiny
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It sounds like the radiator should be replaced. If there is a larger leak, these things won't help. Also, that really makes no sense now. If there is a high pressure leaking from the radiator, how it is staying pressurized or is this something new?
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Thursday, November 21st, 2019 AT 1:56 PM

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