using vinegar to flush cooling system

[old1]

Ok, so I put a gallon of vinegar in my system, and ran it till it was warmed up fully. That was yesterday, so how long should I leave it in there before draining. I want the max cleaning. Should I run it again? If so how often, and for how long?
This is in the 65 mustang

 

[ragtoplvr]

too agressive, be prepared for leaks. Citric acid or commerical cleaner is best.

 

[Trav]

That is not good, any aluminum parts may be toast already, get it out yesterday. If you are lucky given its age it may not aluminum cores or other cooling system parts.

 

[SpitFire6]

I have used 50% phosphoric acid in an aluminium radiator for 24 Hours +. The solution turned black pretty quick. I put vinegar at higher concentrations on my chips.
Vinegar is quite a weak acid.

 

[ripcord]

It's a 1965 Mustang, so no aluminum radiator... just lots of cast iron, brass and copper. I would take a nice drive today and then pull the thermostat out and do a nice thorough back flush to get all the vinegar out.

 

[JHZR2]

I would have done citric acid myself... Or one of the acid free chelating cleaners if I was concerned.

 

[old1]

Right ripcord, there is no aluminum in this old beast. I think I will wait till tomorrow and back it out of the garage, drive it around the block, and drain and flush it out. Thermostat is already out.

 

[Gebo]

I am at a loss for words.

 

[JohnnyG]

Another word of warning. Some of these cars had transmission coolers in the side tank, for automatics that is. If you have an automatic trans in that thing, watch carefully for any increase in fluid level. If the cooler in the side tank gets a hole in it from the acid (of any kind) strange things can happen to coolant/trans fluid levels, not all of them are predictable. However trans failure is pretty much a given.

 

[JimPghPA]

Vinegar is a mild acid. And trany coolers in the radiator of those years are most likely copper or brass, or a combination of both. I do not see any problem here.

 

[JimPghPA]

BTW, you will NEVER find an aluminum trany cooler in a copper radiator, NEVER.

Aluminum and copper are at opposite ends of the eletro-negativity spectrum. If you put aluminum anything in a copper radiator it will cause major corrosion and leaks in short time. Put aluminum pipe fittings on a copper anything and there will be major leaks from all the corrosion it will cause. Nail up copper gutters with aluminum roofing nails and in a few years the corrosion will cause the copper gutters to fall down. Put copper (or brass, which has a lot of copper in it) pipe fittings for the cooling liquid in an aluminum mold and in a few years the corrosion will cause major leaks and ruin the area where the threads were. For house wiring aluminum was at one time used, and if you connect copper wires to aluminum wires they will corrode very badly. There use to be steel connectors to attach aluminum wires to one side and copper wires to the other to make the electrical connection for connecting the two together electrically without having the copper touch and interact with the aluminum. Because they are on opposite ends of the electro-negativity spectrum you can make a battery with a strip of copper and a strip of aluminum and an electrolyte between them.

There is no way the trany cooler in any copper radiator is made of aluminum.

 

[Trav]

Yes it is mild compared to many other acids but not that mild. I bought an old floor drill press that had some rust (no pitting) on the stand shaft. I wrapped it in a few layers of newspaper and wire tied it to the shaft then soaked the paper with vinegar.
In 12 hrs it was rust free and all the rust in the newspaper.

In this old car its probably not a big issue but if anyone reading this thread is considering using vineger in a more modern system, DO NOT use it, use citric acid, it cleans very well and plays well with mixed metals.

 

[Dave9]

You should have put it in (if you use vinegar at all instead of better options), let it warm up and run another 15 minutes, shut off and then an hour later (really I mean just wait till cool enough to depressurize the system) checked the pH. If it is still nearly as acidic you are done. If it is nearly neutral, you need to repeat with fresh vinegar, leaving reacted away solution in is doing no further good. You can get cheap pH test strips on ebay or Amazon. They're not ideal but "good enough" for this purpose once your coolant is replaced with vinegar and water so what you are checking has a low color density.

If it was really crusty inside, odds are that you will need more than one cycle with fresh vinegar, or any other low ~5%-ish acid solution, that I assume you diluted even more to make up the total cooling system capacity, that you had already flushed it and had 1 gallon vinegar plus water topping it off.

 

[nthach]

At that concentration - food-grade vinegar is 5% acetic acid there might be no harm done. You can buy 20% acetic acid OTC but good luck buying glacial acetic acid. Acids are used to passivate aluminum prior to painting, usually phosphoric acid. If you have access to one, I'd pressure test the cooling system to make sure the vinegar didn't eat up your solder or opened up any leaks.

GM called for oxalic acid to flush out Dex-Sludge on the 4.3/5.7L Vortec engines after an IMG failure - can't find the prescribed stuff(Prestone Heavy Duty Cooling System Cleaner) with the sodium carbonate neutralizer. Oxalic acid is stronger and also poisonous - ingestion leads to kidney failure. That's why rhubarb needs to be cooked - the plant contains it.