2007 GMC 2500HD HEATER CORE PROBLEMS!! help

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