Cleaning the Heater Core

[toyo22r]

I thought i would post what i did to unclog my heater core. In my case the heater was mediocore. It was warm but definitely not HOT like my FJ Cruiser. Then it got to the point where at idle I would get no heat at all. Only when the RPMs where up would i get luke-warm air. Here is what I did with fantastic results. (I had tried a "power flush" from Dobbs Tire first and basically was a waste of $100!)

I removed the heater hoses from the engine, thus isolating the heater core. I used the garden hose to flush out the old coolant and it trickled out the other hose. I bought a gallon of muriatic acid from the local harware store. Using a funnel in one of the hoses I poured the acid in until it started coming out the other hose. Then I flushed with water again and used compressed air to blow everything out. I noticed water flowing through much faster now. Repeated this procedure a second time. Then I filled the heater core with 50/50 mix of coolant unil it started flowing out the other hose, at which point I attached to the engine, continued to fill until the 2nd hose will full and reattached it back onto the engine. Filled the system, burped the air and checked the heat. Winds from Hell are blowing from my dash now. Using an IR thermometer it reads 165 degress from the vents! (My FJ with 30K miles on it measured 160 degrees)

So if your suffering from a weak heater definitely give this a shot before replacing the core!

Paul

[ghettosled]

great write-up! i need to do this at some point, but i will wait until spring when its warmer. i think all winter my fan speed was never below 2 in trying to sustain warm temps in the cabin.

[dz63]

toyo22r - In the end, do you think it was the muriatic acid or the compressed air that solved the problem? Do you know if muriatic acid safe for all heater cores?

[toyo22r]

I think the muriatic acid was the key. Iv'e heard you can use vinegar, but its not as acidic so you would have to leave it "soak" probably overnight. Now it does appear to react with aluminum as when it was coming out dropping on the transmission case i could hear is hissing and could smell the hydrochloric vapors but i just ran the water hose at the same time making sure it what was on the transmission remained diluted.

[96paseo]

Water will neutralize muriatic acid. Muriatic acid is commonly used as a stripper for many types of work. Just don't get it on your skin. Those gas tank restorer kits for motorcycles use it to remove rust. Muriatic acid breaks down oxides very well regardless of metal type. Just don't use it on anything galvanized or with a high zinc content.

[TexanF250]

Water does not neutralize muriatic acid. Water dillutes muriatic acid. Big difference. Muriatic acid is water soluable, hence the dillution. You would need a base of some sort to neutralize it.

Glad it worked out for you. I have to admit that I would not have had the balls to do this.

[Manny1337]

got any pictures?

[Stillrunning]

I think this idea is a good one but I will add the safety considerations below from Wikipedia;

"Hydrochloric acid is the solution of hydrogen chloride (HCl) in water. It is a highly corrosive, strong mineral acid
Historically called muriatic acid or spirits of salt"

"Concentrated hydrochloric acid (fuming hydrochloric acid) forms acidic mists. Both the mist and the solution have a corrosive effect on human tissue, with the potential to damage respiratory organs, eyes, skin, and intestines. Upon mixing hydrochloric acid with common oxidizing chemicals, such as sodium hypochlorite (bleach, NaClO) or permanganate (KMnO4), the toxic gas chlorine is produced. Personal protective equipment such as rubber or PVC gloves, protective eye goggles, and chemical-resistant clothing and shoes are used to minimize risks when handling hydrochloric acid.[1]
The hazards of solutions of hydrochloric acid depend on the concentration."

I would also caution using muriatic acid in the full concentration from the container. Try to use the weakest possible solution.