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Duramax and the case of the disappearing coolant!!!!

22K views 23 replies 16 participants last post by  thedeatons 
#1 ·
I have a 2006 Duramax LLY that has been fairly good to me so far. Here is the current problem: I fill the coolant up to the line with coolant, either Dexcool or the Prestone equivalent, and then with a couple days (or a nice long hill towing a big load) I get the Low Coolant Level alarm on the dash. I check the coolant, and sure enough it is below the seam in the coolant reservoir.

When I initially fill it up some coolant pours out of the overflow for some reason. I have seen it dripping from the overflow when the engine is hot too....

What could this be? I am tired of having to carry extra coolant with me on every trip. The engine simply does not get that hot, just enough to turn the fan on at times, but nothing out of the ordinary.... Any ideas?
 
#3 ·
That was the quickest response ever... Okay, now give me an answer that means less money.....???? Any OTHER ideas that it could be MAYBE?
 
#4 ·
Wouldn't I see coolant in the oil or a milkshake in the oil then? My oil looks perfect...
 
#5 ·
The coolant desn't always end up in the oil, I would say have the cooling system pressure checked, If it passes I would say you may be onto more expensive options. I have been there man, it is a brutal feeling when these issues start up

Scott
 
#7 ·
its pry a head gasket, it could be a cracked head, warped head, warped block etc.
 
#8 ·
thedeatons;2049053; said:
That was the quickest response ever... Okay, now give me an answer that means less money.....???? Any OTHER ideas that it could be MAYBE?
Since I doubt you're over 100K mi, take it to the dealer and have them fix it. Your Dmax has a 100K, $100 deductible warranty that covers every engine component.

I also agree to the head gasket. Is the surge tank bulging when the engine is running or does it have a black residue in it? Coolant will not usually show up in large quantities in the oil (only detectable by oil analysis) when a forced induction engine blows a head gasket. Most of it will blow out the overflow.
 
#9 ·
are you maybe filling it to much,and maybe you have a bad coolent sensor?,your only sopossed to fill the coolent up to the full line hot ,theres some room for expansion,also you can pressure test the colling system ,,how many miles/kilm's are on your truck?
 
#10 ·
pressure test and you will see. the head gasket can cause the coolant to go in several places. It could also cause your coolant to blow out the resevoir. do your tests and see what it is. be ready though, if you don't see coolant anywhere on the ground or on the block. how many miles on your truck?
 
#11 ·
It has about 85k miles on it. I have a desert trip in two weeks, so I am going to take it in after that... I will just take the usual bottle of Dexcool with me. I guess I will remove my Edge Evolution for the dealer trip. What do you guys propose I do about the EGT sensor? Do you think it wil be alright if that stays there? OR should I remove the sensor and try to plug the hole I tapped in the manifold? I did it on the underside of the driver's side manifold. Thanks for the help so far guys! James
 
#12 ·
Out of site, out of mind. I removed mine in about 10 minutes and installed a 1/8" NPT plug that you can pick up for under $2. It would be different if you had a gauge, but they will see the wire that is hooked to nothing and may be suspicious. Better safe than sorry. If they see the plug, you can say that you had a piller pod mounted pyrometer then decided you didn't like it and removed it.
 
#13 ·
not always head gasket. i was losing coolant in my truck and did not see anything. after multiple times to the dealer and then getting my friend to help me check it i was loosing about 1 gallon of coolant ever 300 miles out the side of the water pump. the hole was too small for low RPM and idle leeking but as soon as you put pressure on it it would go over everywhere.

I suggest that you go get a pressure tester or find a friend with one. put it up and see if you can find the leek. you dont want to get suck in the desert with that.
 
#14 ·
saratoga;2049636; said:
Since I doubt you're over 100K mi, take it to the dealer and have them fix it. Your Dmax has a 100K, $100 deductible warranty that covers every engine component.

I also agree to the head gasket. Is the surge tank bulging when the engine is running or does it have a black residue in it? Coolant will not usually show up in large quantities in the oil (only detectable by oil analysis) when a forced induction engine blows a head gasket. Most of it will blow out the overflow.
... except the turbo :(
 
#15 ·
Okay, I will try to find a pressure tester somewhere... sigh... when it rains it pours!
 
#18 ·
sorry man i have gone thru the same thing you are doing i had my oil tested and confirmed it was a headgasket and the constant lower coolant i think did my water pump in at the same time got lucky and got all my parts cheap but it was still an expensive job to do make sure you find a good dealer and ask questions if they haven't done any then go to the next one trust me you want some one with some experince working on your truck you don't want to be a guinie pig
 
#20 ·
Coolant Leak 06 Dmax

hey guys i'm a newby but not a newby to the duramax. check the outside of your cylinderhead where it meets the block in the front of the motor this is where i have found the disapearing coolant it is the head gaskets bad disighn that year . this leak is located at eitherside of the block in the front of the block. what sucks is this not small job but is covered under warrenty . oh yeah one more thing keep those fuel filters clean 6000to 9000miles max i've seen plugged up at 5000 many times if you feel like your losin power first thig -change the fuel filter. any more questions let me know -later my nicke name is GRIZ.
 
#21 ·
Thanks guys... I am going to have to systematically test things here...
 
#22 ·
I was losing coolant in my last truck and could not find the leak for a year. I finally tracked it down to the water pump. I also experienced the same issue with mu Yukon, but I knew what to look for.
 
#23 ·
Dang it guys, I was hoping there WASN'T a thread on this. Thought the coolant looked a little low the other day, and sure enough the low coolant light came on. The problem is - I don't remember whether it was any higher than it was. Heck, it took me some looking to find the full coolant mark on the tank!!

I know my Tahoe sometimes does something with the coolant (about once a year), but it has never been found (not the normal places the 5.3 puts it).
 
#24 ·
The dealer confirmed it was a head gasket, they also saw the plug in the exhaust menifold from where my EGT probe was. They asked if I had a tuner on it, I was honest and told them I had an Edge Evolution on it for a while (I took it off to go to the dealer). They said no warranty because of tuner. So, I need to find out whether my VIN is blacklisted. If not I am going to take it to the other GMC dealer and not be so honest, in an effort to score a head gasket replacement. The truck only has 92k miles on it.

If this doesn't work I will be doing the head gaskets myself. Can anyone email the service guide pages to me on the head gasket replacement and also offer some advice on what I am up against, the most difficult part of the process, etc? I am not new to doing this stuff, just haven't done it on a turbo diesel before.... Neither Napa nor Auto Zone carry the head gaskets for it, so it looks like the dealer will get my money for those. Anything else I should get to do the job, assuming I have to do it? Thanks for all the help so far guys.....
 
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