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jbres's avatar
jbres
Explorer
Dec 20, 2014

2007 GMC 2500HD HEATER CORE PROBLEMS!! help

My trucks is a 2007 GMC 2500HD with the 6.0 gas job in it. Truck only has 76,000 miles and I have had it a little over a year. I bought the truck because of how pristine and perfect it was kept. Clean as a whistle, and rust is non existent. It is not my daily driver, I usually run it around 1-2 times a week during the offseason, just to keep it flowing and running.
Well today, all of the sudden on the highway, I start getting a terrible coolant smell coming through the vents. Entire truck windows were terribly fogged up, and heat didn't seem to be working as powerful. Made it home, and found coolant leaking through that rubber drain tube which is underneath the A/C compressor. Coolant not leaking anywhere else whatsoever. Is this a heater core problem?

I follow my owners manual step by step and do preventative maintenance per the book exactly.(I am anal about my truck) Coolant was flushed by the local tire discounters one year ago (only went there bc I had a gift card) and they flushed it with Valvoline max life yellow universal coolant, as they highly suggested me getting the "Dex Death" outta there.

So, I was not the original owner of the truck, but is there any extended warranty GMC has on the vehicles with this low of miles? Should I try and fight Tire Discounters on not using the "Dex coolant" which after I researched, I agreed Dex has quite a few problems in itself. (my 03 Tahoe I use DEX in, and in the overflow tank I can literally see where the Dex has gummed up over the year)
Or any other opinion suggestions on what to do? I have heard this repair can cost upwards of $900 bc of labor involved.
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  • BenK's avatar
    BenK
    Explorer
    Dec 21, 2014
    It is because of Deathcool that today's overflow is pressurized

    It is also translucent so that you can check the level without opening it to let in air (O2)

    During the cool down, the acidic globals gel to stick...there...in the core of either or both the main radiator and/or heater core

    Here are some quotes on this from years ago


    benk wrote:

    Posted: 01/13/05 06:15pm
    Very good article, but there is more to it. They left out stuff.

    OATs & HOATs has several blends. Some has organic, others don't in the mix. Then they also play with concentrations (percentages) of the mixture.

    OATs and HOATs also has higher amounts of plasticizers than American Green. Plasticizer means the chemical softens (melts) plastic. With the newer types of gaskets, this has become problematic.

    OATs and HOATs also take thousands of miles for them to plate (the component held in suspension droping out of via osmosis to plate the metal) and they are *MORE* reactive to O2 (air) than American Green (non-organic) and why Dexcool is nick named "DeathCool" because of the highly reactive organics to O2. American Green takes a few hundred miles to plate the innards. This is why there are issues with certain engine configurations where cavitation creates a spot that has the plating explosively removed. Since it takes thousands of miles to plate, the replate of that spot ditto...takes thousands of miles to replate. Why GM went and removed the radiator cap. Can't fill it via the radiator anymore (sure, the heater hose, etc). The over flow is not under pressure and the "radiator cap" is now there. It's no longer an overflow bottle, but a pressurized tank. You don't have to open to check, just look through the plastic and hope it's full.

    Getting O2 into the system will have the plating attacked and expose bare metal to O2. Just changing a water pump creates potential corrosion if the concentration of materials is not high enough. Or having an air bubble trapped in the system, it will prevent plating and once it starts to rust, OATs & HOATs have a tough time recovering, whereas American Green didn't have that problem.

    After market "one fits all" to top off coolant is not settled yet. Arguable and each vendor will say theirs okay. The jury is still out for me. The professionals do top up with any and the final concentration and percentage mixture between the non-organic to OATs ot HOATs has several numbers with no real concensus, yet. Have seen max numbers ranging from 10% to 20% "new" stuff added is okay, but no agreement yet on what is correct. Think never will they agree, as the numbers of OEM blends too many.

    I'm in the middle of research into this for something else and have been reading the site that has info for the folks in the industry. Have posted the links here several times, so do a search. I'll come back tomorrow or the weekend and append this thread (not at home right now).

    Personally recommend switching to American Green after warranty has expired. That stuff was around for about 5 decades with no problems and the real problem is the extended warranties OEMs used as marketing stuff. They don't want it back for a flush until it's past warranty, IMHO.



    Benk wrote:


    Posted: 04/27/13 09:06am
    Coolant these days are very different from American Green days

    OATs (Organic Acid Technology) and HOATs (Hybrid Organic Acid Tech) with American
    Green going away (silica). All have glycol (alcohol) as the base liquid

    Silica based (American Green) took approx 200 miles or so to plate and protect.
    Think of the silica flakes as small roofing tiles that plated the bare metal

    The organic's of today's coolant has built in acid to etch the metal clean before
    it will plate. That now takes several thousand miles whereas silica took a couple
    hundred miles

    Since organic mixed with acid, highly reactive to oxygen...aka air

    Why today's radiator/coolant system has the overflow pressurized. This is to
    keep OUT air.

    You are NOT supposed to open up the system to check and just view the coolant
    level in the pressurized overflow bottle.

    I can't stand to not check and almost lost my big block to globules of acidic
    plugging up the radiator. Coined the term DeathCool for the new GM DexCool
    (OATs) coolant

    The acid reacts with the O2 and forms acidic globules when it solidifies
    and also emulsified (suspended) acidic liquid. Then during a cool down
    inside the radiator, it sticks to the innards of the radiator to plug
    and rot it out. I had mine rodded out (learned of the new plastic
    tanks and how they seal it without soldering)

    After chasing down dead ends, learned of the actual metrics of this new pink
    or orange coolant. Was lied to by several GM folks (from the local
    rep to folks talked to in Detroit). There are tons of info and still
    to this day...many are in denial that this is the case

    Found some articles that commented that Detroit was fighting the 5yr/100K warranty
    from the Japanese, but their system (dealers, etc) did NOT want to do coolant
    flush every other year under warranty.

    So Texaco was commissioned to develop DeathCool...

    Why keeping 'AIR' out of the cooling system a must at all costs. No matter OATs
    or HOATs


  • Kennedy64's avatar
    Kennedy64
    Explorer
    Dec 21, 2014
    Had the heater core go out in my 00 Silverado a few yrs back (at that time approx 370k miles). We used Bars Leak (located in my area BTW), worked for a short period, once we realized it quit working (I had antifreeze poisoning from breathing it for so long) we replaced the heater core....2 months later I had to replace my radiator, 1/2 the radiator was gummed up from Bars Leak and my mechanic said to try to avoid that type of fix if possible.
    May not happen to everyone but thought I'd share.
  • ls1mike's avatar
    ls1mike
    Explorer II
    Dec 21, 2014
    So lets start this way. You truck is LS based. Dex cool does not affect it like it did the 3.1, 3.4, 3800, 4.3, old 5.7.
    You have a pressurized overflow tank.
    If you keep Dex in it you are fine. You have a dry intake no coolant or oil touch it. The problem in the past was low coolant, air and acidity eating the plastic intake gaskets.
    What you see in the overflow tank of you Tahoe no big deal, I have that in all my Dex cars.

    My 00 WS6 has had DEX from day one and it is not pressurized, the LS1 does not suffer the DEX problems.(just a smaller aluminum block 6.0. It does not have a pressurized overflow tank like your truck and mine)
    NOW having said all that. I would find who put the wrong stuff in it and have words. :). That will mess everything up. It will turn Dex to a gel like substance, clogging everything leading to failure in the highest point first...heater core
    My guess is your heater core needs to be replaced. Then you need to flush the system and put the Prestone Dex in it.

    I run the Dex in everything I have (all GM). I had to do the intake gasket on the Grand Prix (s/c 3800) but the updated metal gaskets pretty much solve the problem.

    I too only use my truck to tow so it sit for long periods. I flushed this past spring and put Prestone Dex back in. Just like the Trans Am, clean as a whistle in there.
  • B_O__Plenty's avatar
    B_O__Plenty
    Explorer II
    Dec 21, 2014
    First off the truck is 8 years old...there is not going to be any warranty from GM. It's doubtful that using the wrong anti-freeze contributed to any of this. It has been my experience that any of these services should be done at a GM dealer. They fix cars. Tire shops fix tires...Quite possible they used too much pressure and blew a hole in it but you'll never prove it. Bring it to a GM dealer not some el-cheapo shop, pay the money and get it fixed right and put the correct coolant in it...end of story..

    B.O.
  • BenK's avatar
    BenK
    Explorer
    Dec 20, 2014
    GM is OATs (Organic Acid Technology) and that stuff does NOT do well with any
    air (O2) in there, nor any of the sealers

    Best to have the heater core fixed/replaced and the whole cooling system flushed

    If O2 gets in there, common for it react with the acid to form globules of acidic
    gel to plug and rot out the core of the radiator and heater cores
  • jbres's avatar
    jbres
    Explorer
    Dec 20, 2014
    yea, the truck is only used for rv travel trailer towing trips. So must be a good permanent fix. And ill try the local shops, and hell they can have it until spring when I start towing with it. lol
  • Trackrig's avatar
    Trackrig
    Explorer II
    Dec 20, 2014
    Don't laugh, Bars leak can fix a lot of things. I always carry several cans in my hunting rig because it seems like every stick out there is aiming at my radiator and sometimes they find it.

    Heaters are usually expensive to fix due to time consuming labor to get to them in the tight spaces. If you just drove it around town I'd go with the Bars leak, but if you use it for longer RV trips, then it looks like you'll have to spend the money.

    Sometimes on labor intensive jobs I've found a smaller shop to do it cheaper by telling them they can have the vehicle for two weeks and use it for filler work when things are slow.

    Bill

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