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Discussion Starter #1
Hey. I don't believe I have updated my signature so my ride is a 2015.5? LML with around 94k miles.

While periodically checking fluids, I noticed that the overflow side of my tank was up to the seam while the reservoir side was slightly above the seam. At the time the engine was warm and the upper radiator hose was hard. I let it cool over night and checked it again. Coolant is in the same spot as in the picture below and I could squeeze the upper radiator hose easily.

I'm guessing the surge tank cap is not regulating the flow correctly? Is my guess correct? Also how do I remove the coolant from the overflow side?

Any help would be appreciated!
 

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Try taking the cap off and soaking it in hot soapy water overnight, or replace. Usually if the cap is stuck the upper rad hose will be collapsed. If you want to get some of the coolant out of the overflow you can drain a bit of the coolant with the cap still on, and it will act as a vacuum and suck the coolant from the overflow into the reservoir side. The overflow should be about 1/3 full of coolant when the levels are correct
 

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Discussion Starter #3
So remove the hose on the top side of the surge tank and pull a vacuum on the surge tank there with the cap on? Or is there a different way that you are recommending? Can I drive it as it is and eventually it will correct the levels?
 

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Leave everything hooked up to the surge tank and pop open the lower rad hose where you would normally drain the coolant. This will pull the coolant from the overflow into the reservoir side.

I wouldn't worry about it honestly. As long as you aren't getting excess pressure in the system or losing coolant you should be fine. Try cleaning or replacing the cap and keep an eye on the levels.
 

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Discussion Starter #5
So my coolant level hasn't changed after putting a new cap on. I checked my coolant after driving it tonight and it looks like coolant is coming out from the overflow side.

Is the section of the tank I circled in red a pressure relief valve or is it where the overflow pukes coolant from?

I guess what I'm trying to ask is do I have a bad surge tank or do I potentially have a head gasket issue?
 

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Discussion Starter #6
My truck sat for 9hrs last night and this morning I checked the upper radiator hose and couldn't squeeze it very much. I checked the oil and my oil level is fine and does not look milky. I opened the cap on the surge tank and it hissed as as pressure was relieved. With the cap off I saw some white scum in the surge tank.

From the little bit of searching the forum, it seems like it may be an EGR cooler leak.

Does this conclusion seem correct? How to I verify that there is an EGR cooler leak?
 

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My truck sat for 9hrs last night and this morning I checked the upper radiator hose and couldn't squeeze it very much. I checked the oil and my oil level is fine and does not look milky. I opened the cap on the surge tank and it hissed as as pressure was relieved. With the cap off I saw some white scum in the surge tank.

From the little bit of searching the forum, it seems like it may be an EGR cooler leak.

Does this conclusion seem correct? How to I verify that there is an EGR cooler leak?
Sounds like head gaskets to me with the radiator hose staying that hard for that long.
 

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I had an egr cooler leak and it was noticed because the coolant level was lower after pulling my trailer. I didn't notice a change after driving in town, though it may have occurred. I looked and looked for a leak, couldn't find one. Discussed my observation with local garage and he said he thought it was EGR cooler leaking. GREAT - how do you test to be sure that's the problem? I asked. No test - they leak while hot and underload, no bench testing shows the leak. I was skeptical, but he is a good mechanic so trusted his judgement. He was correct. So, if you are loosing coolant, and there is no other leak detected, it MAY be a leaky EGR cooler.
 

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Block the exhaust flow and then bypass the coolant flow thru the cooler.....takes the EGR pressure out of the loop for testing.
 

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Discussion Starter #10
Thank you for all of your responses. My head gaskets are leaking and I am taking advantage of my service contract for the repair.
 
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