Coolant leak from valley

NickInMN

Member
Aug 30, 2021
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My lbz swapped Hummer has had a coolant leak for a while now. I thought it was coming from the oil cooler elbow so I replaced the gaskets. It still leaked so I put the fleece adapter in and it still leaks. I was doing some maintenance on it today and I noticed this leak. It is coolant and it looks like it is coming from the valley. The weird thing is it looks wetter below the valley than what's coming from the valley. I'm guessing the turbo coolant line is leaking but could it be anything else?
 

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NickInMN

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Aug 30, 2021
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Turbo coolant line would be my first guess.
I went out there today to take a look and I don't think it is the turbo coolant line. It is dry by that. Any other ideas?

EDIT: Doing some more reading it looks like it could be the rear engine cover. For now I think I'm going to clean everything up and drive it for a while to see if that helps locate the leak.
 

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Last edited:

1FastBrick

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Dec 1, 2016
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I don't have any experience there. But I would assume it would get worse with time. There is an O-ring as well as sealant so if its leaking past that, I would think it has to be pretty significant and that it's not going to just be ok. You might even be contaminating the oil which is a really bad thing...

That takes out bearings and other components...
 

NickInMN

Member
Aug 30, 2021
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I don't have any experience there. But I would assume it would get worse with time. There is an O-ring as well as sealant so if its leaking past that, I would think it has to be pretty significant and that it's not going to just be ok. You might even be contaminating the oil which is a really bad thing...

That takes out bearings and other components...
It looks like that shouldn't be an issue, according to this image in AllData showing where the sealant goes. That's definitely food for thought though, I appreciate it.

1747684603738.png
 

NickInMN

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Aug 30, 2021
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What about the coolant line on the other side of the turbo?
I think what you're referring to are in the two pictures in my second post. The first picture are the two coolant lines going into the turbo on the driver's side. The second one is the little rubber bend in front of the turbo. Both areas looked dry. Is there a line I'm missing somewhere?
 

SoCalMike

Active member
Dec 12, 2010
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I think what you're referring to are in the two pictures in my second post. The first picture are the two coolant lines going into the turbo on the driver's side. The second one is the little rubber bend in front of the turbo. Both areas looked dry. Is there a line I'm missing somewhere?
Copy. I had to relook at the picture. Did you check the EGR coolant hose from thermostat to egr? I just did my head gaskets and the only places that have coolant on top of the engine are the thermostat, turbo coolant lines, cooling hose going to the radiator. Not much else. Did you check the turbo thermostat? its connected to the hard pipe coming off of the thermostat.

1747836511971.png
 

NickInMN

Member
Aug 30, 2021
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Copy. I had to relook at the picture. Did you check the EGR coolant hose from thermostat to egr? I just did my head gaskets and the only places that have coolant on top of the engine are the thermostat, turbo coolant lines, cooling hose going to the radiator. Not much else. Did you check the turbo thermostat? its connected to the hard pipe coming off of the thermostat.

View attachment 130680
The EGR was deleted when I bought the truck. Everything is dry at the front of the engine. I think it has to be the orings on the back cover.