Sludge in radiator with bubbling water sound in heater

Tiny
VERTIMUSMAXIMUS
  • MEMBER
  • 2005 CHEVROLET MONTE CARLO
  • 3.4L
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 133,000 MILES
When I filled up the radiator to full the reservoir drained and after driving a block I noticed a sound of water in the dash. When I accelerated from. A stop is sounded like water and bubbles rushing back against the dash. The heater had a smell strange at first unless I got used to the smell. Then the heat started filling the car with fog. The window fogged up. Next day I figured I'd check the radiator again and it was caked with a brown sludge under the cap. Lots of it. Reading online saying it could be bad Dex coolant gone bad and turned to sludge. I have heard it can be a head gasket. A cracked block. I have heard it could be coolant leaking into the transmission cooler. I don't. Transmission fluid in the radiator. Doesn't overheat. Took it to the dealer and he said hes going to have his mechanic look at it but i'm lost as to what to do.
Tuesday, September 1st, 2020 AT 5:57 PM

4 Replies

Tiny
KASEKENNY
  • MECHANIC
  • 18,907 POSTS
Sounds like you could have two issues. The first of the noise, smell, and fogging of the windows is a leak in the heater core. Basically you have coolant in the HVAC system and when you have the air on, it is blowing steam from the coolant into the inside of the vehicle.

As fro the sludge under the cap, can you get a picture of it? You are correct that it is most likely a cooler issue or a head issue. Here is a guide on how to check the head gasket:

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

Once we rule this out and get a picture of it we can get on a possible cooler issue. However, we need to go step by step so let us know what you find. Thanks
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Tuesday, September 1st, 2020 AT 6:18 PM
Tiny
VERTIMUSMAXIMUS
  • MEMBER
  • 4 POSTS
Here is a photo of the radiator. There was more then this. The entire mouth was clogged into the cap like clay or gel.
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Tuesday, September 1st, 2020 AT 6:51 PM
Tiny
VERTIMUSMAXIMUS
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  • 4 POSTS
Here is another from a mechanic from another country, but it's hard to understand what he says so I was really lost after we spoke. His accent was hard for me. I could tell he was having a hard time hearing me too. He would stare at me when I spoke to him like he didn't understand me.
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Tuesday, September 1st, 2020 AT 6:54 PM
Tiny
KASEKENNY
  • MECHANIC
  • 18,907 POSTS
This is oil. We need to do the head gasket test from above. Let's start with that and go from there. Let me know if you have questions. Thanks.
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Tuesday, September 1st, 2020 AT 7:33 PM

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