Coolant leak under car behind engine

2006 CADILLAC DEVILLE DTS
140,000 MILES • V8 • 4WD • AUTOMATIC
Avatar
ANTHONY A.TRAIN RAMSEY
  • MEMBER
  • 3 POSTS
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.
Jun 8, 2022 at 5:48 PM
Advertisement
Avatar
SQM
  • CERTIFIED EXPERT
  • 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.
Jun 8, 2022 at 10:21 PM
Avatar
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.
Jun 9, 2022 at 5:41 AM
Advertisement
Avatar
SQM
  • CERTIFIED EXPERT
  • 6,383 POSTS
Got it. So, it likely just overheated due to being low on coolant.
Let me know what you find.
Jun 9, 2022 at 8:35 AM
Avatar
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.
Jun 9, 2022 at 2:23 PM
Avatar
STRAILER
  • CERTIFIED EXPERT
  • 53,854 POSTS
Thanks for letting us know, let us know if you need more help.
Feb 10, 2025 at 12:24 PM