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Discussion Starter · #1 ·
Alright...So I think my HG are going bad... :'( Temp gauge will dance all over the place...from 160 to 210 to 185 to 210 to 160..etc... I have replaced the thermos and bled it...cleaned the cap. If it sits idling for more than 5 min after being driven, coolant will surge out the coolant tank. I noticed a very small leak on the lower rad hose where the little hose T's into it...thinking that may be causing it but I have been also get horrible mileage lately too and can smell antifreeze while my truck is running but i cant smell it coming out the exhaust... I'm going to try a new cap and replacing the lower hose this weekend...hoping that fixes it.

Any thoughts?
 

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After you fix the lower hose and cap, do the upper rad hose squeeze test after it sits overnight.

Does the plastic coolant tank have a black film in it?
 

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Discussion Starter · #3 ·
Will do.

No black film that I notice...

I hoping that the hose or cap is the issue...Could a faulty water pump be causing issues like this? When I looked up underneath at it I couldn't really tell if it was leaking because coolant spilled down the front of the motor when i changed the stats...
 

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Faulty water pump could definantly be your culprit. Replace it, your lower radiator hose, and your radiator cap and see if that fixes it. If not it's probably head gaskets.
 

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Discussion Starter · #5 ·
Alrighty. Question about the water pump...is it a PITA to change like the LLY's or LB7s? gottta take the harmonic balance off and what not?
 

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Discussion Starter · #6 ·
Faulty water pump could definantly be your culprit. Replace it, your lower radiator hose, and your radiator cap and see if that fixes it. If not it's probably head gaskets.
Off topic but do you got any pics of your truck? I'm wanting to go to 20x10 or12s...your setup seems pretty dang close to what i'm picturing in my head

-Lance
 

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Yeah man go to my profile and theres a couple pics on there. Their kinda outdated and were taken before my tow mirrors were put on but you'll be able to see the wheels and tires!
 

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And yeah the water pump is definantly still a PITA to get to haha!!
 

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Discussion Starter · #9 ·
i see very little pic of it haha.

yea i just found the DIY for the water pump...yeehawww!!!
 

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Discussion Starter · #10 ·
Heres another ??? if it was leaking into my EGR would it be smoking in the exhaust?
 

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Discussion Starter · #11 ·
So she warmed up this morning to around 185 on the gauge before I left for work...after about 10 min of driving the temp dropped down to nothing...and I have brand new thermos in and put them in the same way the old ones came out...any ideas why she does this? She did start to "heat" back up on the gauge until I pulled a big hill...once she started to "heat" up she went to the 3/4 mark on the gauge just past 210...so I pulled over.. shut her down and the coolant tank was full...I let it settle, got a new cap, topped her back off (I opened the bleeder on the stats while doing this) and then drove to work with good heat...

I just don't know...Going to change the lower hose this weekend in hopes that it fixes the problem...I'm thinking maybe because of the small leak on that hose that is the culprit... :/ ahhhh I LOVE MY DMAX!!
 

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Discussion Starter · #12 ·
Well had another issue this morning...she got up to 185 no higher...driving to work...temp drops to nothing...going up a hill she starts to climb back up...pegs out at 260 ENGINE OVERHEATING/ COOLANT OVERHEATING comes on...I pull over she blowing coolant back into the tank out the overflow and chugging hard back into the coolant tank...now I got this black crap in the tank, I didn't get a pic of it on my fingers but got one of what it looks like from the outside of the tank...a fellow duramax'er passing by stopped (hes got a built LB7) and said that looks like carbon from your EGR...so could my issue be the egr is leaking?? what causes that? what are the fixes? I'm about ready to run my truck into a tree...haven't even put 5k on it and I've been babying it...:help:help:help
 

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Discussion Starter · #13 ·
And if this is EGR would doing the blocker plate eliminate the issues or should I do the whole EGR delete kit?
 

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Discussion Starter · #14 ·

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I think you would want to also bypass the coolant line. Directly from the heater core to the thermostat housing.


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There plenty of options through our vendors on this site, and they great to do business with


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Discussion Starter · #17 ·
I think you would want to also bypass the coolant line. Directly from the heater core to the thermostat housing.


So doing that I wouldn't have any heat right?? No bueno with -20 weather we been getting up here haha.

but I do have to get this figured out ahh Thanks for the reply man.
 

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Discussion Starter · #18 ·

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Discussion Starter · #19 ·
and if I do this delete will I have to re-tune my truck?
 

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Block the egr and bypass the egr cooler hose as mentioned by mwar410 then report back. Even if egr is not the problem your truck will be happier.
 
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