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Discussion Starter · #1 ·
Long story short, had my water pump replaced and when I got the truck back it had the green antifreeze instead of the orange stuff then one night about a month and half ago, I replaced the two thermostats because I was freezing my ass off and when the time came to refill the coolant I lost when replacing the thermostats, I had a galon of dexcool and I added it to the green stuff, it was my mistake I was just so desperate to get out of the cold and I didn't pay attention.

Before I did that, I had very little pressure on the upper radiator hose, after having the truck sit overnight, now the upper radiator hose is Hard as a rock and it's puking coolant, I have flushed the system myself following instructions I found in the forum, it didn't work, then just to make sure I took it to jiffy lube and they vacuum the system and added new dexcool, still the hose is hard as a rock and today, I installed a blocking plate for the EGR and , I think is even worse, does it sound like a headgasket for sure or is there anything else I can check before admitting that I need new headgaskets?.

I bought the truck about 3 and a half months ago, and I don't think I have 3k miles on it, it's an 05 lly and it has the original head gaskets and 230k miles on it.
 

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Im subbed my sisters dmax they switched from dex to generic and they also have odd problems and coolant tank is always under pressure even if it sits for a couple days
 

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Sounds like head gaskets, could be just a coincidence that they went about the same time the water pump did. I wouldn't mix Dex with other coolants and vice versa, regardless of what the label on the green stuff says.
 

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With 230k on the clock headgaskets could be a possibility. I dont know much about mixing the dex with other stuff, but it could still be HGs and be unrelated to your coolant issue. Any other symptoms of HGs? Having to add any coolant?
 

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It is a really good, cheap and accurate test for how simple, that you have a HG issue with a hard upper hose after truck has sat over night. I am not sure it would be the green coolants fault, it just might of been time for the HG to let go. Lack of warn heater is a sign too!

Its possible to be an egr thing, or cap, but unlikely from what your describing

With out looking at it, but going by what your say, its possible HG issue. Have the system pressure tested.
 

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If for some reason unknown to me it happens to be an EGR issue, i have a good (but dirty) EGR cooler i took off mine that id be willing to give away lol.
 
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Discussion Starter · #7 ·
It might be that my headgaskets were just starting to go when I bought the truck, and messing around with the coolant accelerated the problem, when I bought the truck, I checked the hose everyday and it was to the point I could still press it with one hand, but when I removed the cap I could hear a little bit of air coming out, then when I got it back from the shop with the green stuff, the hose was a little bit harder in the morning, but when I added a full galon of Dex-cool, the hose was hard as a rock the next day.

I also replaced the Cap for a new one same problem and to be sure it wasn't the EGR I used a blocking plate, I don't see any white smoke, the heat works fine and the truck runs pretty good and I get the low coolant warning after it pukes a couple of bottles worth of coolant.
 

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Does sound bad head gaskets-- the EGR cooler will not retain the pressure like the bad head gaskets do. Mixing coolant can cause problems-- but it takes months for that to happen. Most guys are in "Headgasket" Denial when it happens to them.
 

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I do know if you mix other coolants with dexcool it will cause your coolant to become sludgy and plug stuff had to replace a few radiators because of it but id think if it was flushed first youd be fine
 

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I've read of others that have had their water pumps replaced only to have HG issues later. I'm thinking the anti freeze has a place to drip from with a bad pump. Button up the system and the pressure causes a hard hose and puking. Am I wrong?
 

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I do know if you mix other coolants with dexcool it will cause your coolant to become sludgy and plug stuff had to replace a few radiators because of it but id think if it was flushed first youd be fine
X 2.... That makes a nasty mess
when u mix coolants.




I've read of others that have had their water pumps replaced only to have HG issues later. I'm thinking the anti freeze has a place to drip from with a bad pump. Button up the system and the pressure causes a hard hose and puking. Am I wrong?
Yep my waterpump started leaking out the weaphole, that's the first thing I had noticed when I started having hg issues.
 

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It might be that my headgaskets were just starting to go when I bought the truck, and messing around with the coolant accelerated the problem, when I bought the truck, I checked the hose everyday and it was to the point I could still press it with one hand, but when I removed the cap I could hear a little bit of air coming out, then when I got it back from the shop with the green stuff, the hose was a little bit harder in the morning, but when I added a full galon of Dex-cool, the hose was hard as a rock the next day.

I also replaced the Cap for a new one same problem and to be sure it wasn't the EGR I used a blocking plate, I don't see any white smoke, the heat works fine and the truck runs pretty good and I get the low coolant warning after it pukes a couple of bottles worth of coolant.
Bad EGR cooler just leaks coolant, it won't cause a hose erection. Also, you have to bypass the coolant lines on the EGR to leakproof it, the blocker plate just blocks the gas recirculation.
 

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Discussion Starter · #13 · (Edited)
I'm passed the stage of Headgasket denial, I been watching every video I can and reading up on it, because a headgasket job goes for about 7000$ in my area, I think I'm going to tackle the job myself with a friend, when the weather gets better.
 

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Discussion Starter · #14 ·
Bad EGR cooler just leaks coolant, it won't cause a hose erection. Also, you have to bypass the coolant lines on the EGR to leakproof it, the blocker plate just blocks the gas recirculation.

I"m going to do that in the next couple days, I was going to do it yesterday but just my luck one of the screws got rounded and I couldn't get the EGR tight and I got a very small air leak where the plate goes.
 

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Discussion Starter · #15 ·
I've read of others that have had their water pumps replaced only to have HG issues later. I'm thinking the anti freeze has a place to drip from with a bad pump. Button up the system and the pressure causes a hard hose and puking. Am I wrong?

That sounds like what happened to me, Because after replacing the water pump, I started having issues with the hard radiator hose, I took the truck to a guy that's not a diesel guy (this is my first diesel) and I have been thinking it was his fault for switching from dexcool to the green stuff probably without flushing all dexcool and then me adding the dexcool back when I had the green stuff, that probably didn't help either.
 

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Discussion Starter · #16 ·
Bad EGR cooler just leaks coolant, it won't cause a hose erection. Also, you have to bypass the coolant lines on the EGR to leakproof it, the blocker plate just blocks the gas recirculation.

What happens if you drive around with a loose radiator cap? I tried it today and it stopped puking coolant and there is no pressure on the upper radiator hose, would driving like that be more harmful than driving with all that pressure on the cooling system?
 

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Head gasket or EGR?

Hello I'm james I'm having similar issues. I also mixed a gallon of regular coolant a long while ago. Then also after a water pump replacement it started with the hard hose and puking coolant. I took the o ring out of the cap. Is there any other answer than a bad head gasket?
 

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Discussion Starter · #18 ·
Hello I'm james I'm having similar issues. I also mixed a gallon of regular coolant a long while ago. Then also after a water pump replacement it started with the hard hose and puking coolant. I took the o ring out of the cap. Is there any other answer than a bad head gasket?

In my case, all things do point to bad headgaskets, I still have to do bypass the EGR, but am not very hopeful, what do you mean you took the ring out of the cap? did it help?
 

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What happens if you drive around with a loose radiator cap? I tried it today and it stopped puking coolant and there is no pressure on the upper radiator hose, would driving like that be more harmful than driving with all that pressure on the cooling system?
IMO I would not drive with the cap loose. The cap is designed to maintain the cooling system at 15psi when it is at operating temp. This raises the boiling point of the coolant in the system. If there is no pressure on the cooling system you may be at risk of boiling and evaporating your coolant. I'm fairly new to the Duramax myself, but maybe someone here with more experience with these motors can explain better....
 

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I've never mixed anything into the Dexcool, but I did notice that after I recently flushed and renewed the six year old Dexcool the upper hose is noticeably softer in the morning. It wasn't hard before, but it had a little resistance, and now it can be squeezed shut with two fingers.

This is a low mileage Lb7 BTW, and I don't have any reason to suspect a HG problem.
 
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