Coolant leak under car behind engine

Tiny
ANTHONY A.TRAIN RAMSEY
  • MEMBER
  • 2006 CADILLAC DEVILLE DTS
  • V8
  • 4WD
  • AUTOMATIC
  • 140,000 MILES
Just started up this DTS after sitting for almost a year. After letting it run for a while, I came outside and saw white smoke coming from it and hissing. Turned the car off and saw that it overheated, and there was coolant pouring from under the car and from behind the engine. The radiator is new, the front hoses look good, and it felt like coolant was running through the hoses to and from the radiator. Does anyone know if it's a hose or something bigger? Any help would be great.
Wednesday, June 8th, 2022 AT 5:48 PM

5 Replies

Tiny
SQM
  • MECHANIC
  • 6,383 POSTS
Hello,

Did the white smoke come out of the tailpipe or was it under the hood?

If the white smoke is out of the tailpipe, then it could be due to a blown head gasket. With a blown or leaking head gasket the coolant will mix with oil and that will create white smoke out of the tailpipe. A blown head gasket can also make the oil milky white in color.

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

As for the leak, you will have to do an inspection and see if you are able to find it. If the leak is from the back of the engine bay, then it could be one of the bypass hoses.

https://www.2carpros.com/articles/car-is-leaking-coolant

Please let me know a little more details of what you have been experiencing.

Thank you.
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Wednesday, June 8th, 2022 AT 10:21 PM
Tiny
ANTHONY A.TRAIN RAMSEY
  • MEMBER
  • 3 POSTS
It was from under the hood. I had filled the reservoir and let the car run for a while and when I came out it had smoke coming from under the hood, hissing sounds and the car overheating. When I looked under the car coolant was running out. When I opened the hood, white smoke was coming from the back of the engine. I'll check the bypass hoses and see what I find. Thanks.
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Thursday, June 9th, 2022 AT 5:41 AM
Tiny
SQM
  • MECHANIC
  • 6,383 POSTS
Got it. So, it likely just overheated due to being low on coolant.
Let me know what you find.
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Thursday, June 9th, 2022 AT 8:35 AM
Tiny
ANTHONY A.TRAIN RAMSEY
  • MEMBER
  • 3 POSTS
Just got done inspecting the hoses and it's definitely the coolant reservoir hose that runs from the bottom of the coolant reservoir tank to the T that connects to the heater core hose. It has a hole in it. I just have to figure out how to get it out to replace it.
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Thursday, June 9th, 2022 AT 2:23 PM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 50,622 POSTS
Thanks for letting us know, let us know if you need more help.
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Monday, February 10th, 2025 AT 12:24 PM

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