HVAC heat blows warm/hot on drivers side, cool/cold passenger side (warranty issue)

[Daox]

I've emailed Peak, Valvoline, and Pentosin to see if they have any recommendations.

[MetroMPG]

If it's literally like vaseline, then it's petroleum based. Gasoline should make quick work of it.

Maybe not what people want to be flushing their heater cores with, though!

[Cobrajet]

I am sure something will dissolve this stuff. But if that is true, why is Mitsubishi replacing heater cores under warranty instead doing some kind of less expensive chemical flush? I assume it's because they know the core will just sludge back up AGAIN??

It almost has to be a defect with the cores themselves...but what? Did they use some kind of defective aluminum? Does the design of the core result in hot/cold spots or air bubbles that cause this kind of emulsion? Is the goop in the heater core the result of some kind of 'sedimentation' of a semi-solid substance caused by a chemical reaction between the engine and coolant that may be occurring somewhere else in the cooling system, and the heater core is just where it collects? This is a weird problem.

Haven't we had a few people randomly need to replace radiators? I would love to 'autopsy' one as Daox did with this core. I'd love to know if this sh!t is found anywhere else in the cooling system.

[Top_Fuel]

Remember the Dexcool mess? Some of Dexcool's issues were supposedly caused by exposure to air. The manufacturer of Dexcool was very specific about making sure the cooling system was properly bled when filled. Maybe something similar is going on here?

I can see a scenario where our cars weren't properly bled at the factory...then they sit for weeks/months in transport and on a dealer lot before they are driven on a regular basis...and an air pocket in the heater core finally makes its way out.

There is a TSB for how to flush Dexcool systems that have sludged up. It mentions a specific part number for the flush/cleaner...GM Part Number 12346500 (Heavy Duty Cooling System Cleaner). This is not the liquid "Super-Flush" stuff you buy at the parts store. It's much stronger. This stuff came in a POWDER form in a yellow Prestone container (like a Pringles chip can). It contained 2 materials:

9 dry oz of Oxalic Acid (acid/cleaner)
2 dry oz of Sodium Carbonate (neutralizer)

Prestone made it for GM...but has since been discontinued.

Supposedly the following 2 materials can be used to duplicate Prestone's product:

Acid/cleaner: Wood bleach
Neutralizer: Arm & Hammer Super Washing Soda

[Daox]

No answers back yet from the coolant guys. I'm thinking they forgot about me. The Peak guys went back and forth a little bit. The rest I just haven't heard from.

Anyways, I was in the garage this weekend and I took another look at the heater core and end tank. This is what the stuff looks like after its had a few days to dry out.

[01-7700]

looks waxy - another removal medium to try... boiling hot water

[tytotheler92]

That's gotta be something from the assembly of the engine. How weird.

[Top_Fuel]

Remind me not to drink the water if I ever travel to Thailand.

If we do figure out how to clean this stuff out of the heater core...it makes you wonder what the radiator looks like.

[Daox]

Well, thankfully the radiator has larger passages, so its way less likely to be an issue. I think we've heard of one radiator being replaced? I know mine doesn't have any issues cooling, and I run a pretty big grill block. Only the upper mail slot is open on the front of my car.

[01-7700]

It will be interesting to see if those cores that have been replaced develop any issues.