Tried it, it works. Be careful tho, it builds up pressure from the reaction. Not sure if letting it sit over night is a good idea due to this. It bubbles, and bubbles, even after the car has cooled down, as if the water was still at 220F. I used about 1.5lbs of citric acid and dissolved in water, then poured in, making sure the solution was completely dissolved. I'm going to keep experimenting with this, may try some Thermocure next and see what comes of that. May tell me how good the citric acid worked. The beauty of the citric acid is it is dirt cheap.

BTW - got the idea from this guy: https://www.bobistheoilguy.com/forum...tric_Acid_Flus

Mercedez Benz - https://www.eeuroparts.com/Parts/531...-000989102511/

 

Interesting, Ive got a partially plugged heater core in my s10 that i cant unclog even with straight CLR.Where did you buy the citric acid?

 

Amazon. can get 20 lbs for $22. I started with 2lbs just to test. I am still flushing with fresh water, only draining thru the petcock cause I'm too lazy to take other stuff apart. if you try it, just be careful. I flushed yesterday, and went back today to flush some more and there was still some pressure build up. be ready to stay on top of it.

 

Also, I've read reports of guys doing this and then they get leaks. most attribute this to some stuff that was clogging a hole, and once dissolved, you got problems. be ready for that too

 

I saw that in the link you provided.What makes it work, heat or pressure or both/neither?.Maybe i could just fill the heater core, thats really where my issue is.

 

chemical reaction. I assume the byproduct is some sort of gas, O2 or something. that is why you need to be careful. will build up pressure. Or, you could just try Thermocure - they have amazing products.

 

I just got done cleaning and flushing my home heating system (HW baseboards) with ZEP's version of CLR. It is strong!
Ingredients:
INGREDIENT Water (Solvent); Carbonyl Diamine (Descaler); Hydrochloric Acid (ph Adjuster); Sulfamic Acid (Descaler); C9-11 Alcohols Ethoxylated 4-6EO (Surfactant – Emulsifying Agent); Glycolic Acid (pH Adjuster); Citric Acid (Preservative); Quaternary ammonium compounds, coco alkylbis(hydroxyethyl)methyl, ethoxylated, chlorides" (Corrosion Inhibitor); Ethanolamine (Solvent); Isopropanol (Solvent); Propargyl alcohol (Corrosion Inhibitor); Acid Yellow 17 (Colorant)

 

you can do a search on what chemicals are safe for aluminum. hcl may not be one of them

 

update on this, finally got around to flushing the remaining out yesterday. man, either this stuff really works or I just had some really dirty coolant passages. I'd like to take apart one of my hoses and see how clean they are, but that is for another day.

This time I decided to just keep the radiator drain open and be on stand by with hose to keep refilling while engine was running. started/stopped engine a lost letting the dirty water pump back into radiator until it stopped flowing, shut off engine, tossed dirty water, filled back up started engine, rinse and repeat. did this for about 30-45 minutes. it was a process until finally clear water started coming thru.

The solution was first flushed (not very well) back in mid-late may and has been brewing ever since while I was replacing headliner. at least 2 weeks. over all, I'm happy with results but wondering if I used too much citric acid. I must have flushed with at least 30 gallons of water to clear everything out, that would be a low ball park estimate.

 

You have to flush so many times because the fluid that is in the block only gets diluted by the new flush.
Where the water pump bolts to the block leaves, what, about 4-5" ? of liquid left in the block.
Pull the low 1/4" NPT plugs on the sides of the block to completely drain.
One is at the back of the starter, and the one on the drivers side might have a knock sensor in it.
Did you have the heater ON while doing the flush to clean the heater core?
I'm glad it finally flushed clean for you.

When you are finally satisfied, use distilled water along with your new coolant. Tap water = corrosion.