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I got the idea from this article, where it suggests cleaning your washing machine using chlorine bleach and then vinegar. I have successfully used this method to clean my household washing machine more than once.

Would it be all right if I use chlorine bleach and then vinegar to clean my car radiator interior (coolant system ducts)? Or is there any chance of any damage?

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I've read that mixing vinegar and bleach can release toxic chlorine gas. If you really want to use both, you might want to flush with water in between. – RedGrittyBrick Aug 1 '14 at 16:09
@RedGrittyBrick Yes, definitely. If you please take a look at the referred article on cleaning washing machine, you will notice that they use chlorine, flush the machine and then use vinegar. But see the answer below. – Masroor Aug 1 '14 at 17:18
up vote 11 down vote accepted

I would definitely not intentionally put sodium hypchlorite bleach in my radiator. Vinegar is one thing, but the sodium hypochlorite will attack anything aluminum in your radiator, intake manifold, block, or head. It'll also attack (vigorously) any rubberized gaskets that're in contact with coolant. Even disregarding outright measurable damage, it'll release gobs of aluminum ions & migrate them around inside the cooling system where they're not wanted.

I can't think of any good reason to use bleach - there's nothing in there that would call for the stuff. No organics building up, no discoloration you care about. Now, the vinegar would help alleviate any problems you might have introduced by not using distilled water to mix your antifreeze - the vinegar will tend to relieve the mineral deposits you may have gotten from your tap water. Bleach? No such purpose.

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I would not use that solution to clean my radiator. Remember that a radiator itself is primarily made of fairly thin aluminum. The bleach/vinegar could very easily damage the structure and weaken it. A washing machine is made of (in most cases) a steel drum coated with porcelain, or stainless steel, both of which are very sturdy and are made to last a long time through a lot of abuse. Your car radiators only jobs are to maintain internal pressure, keep sealed, and allow the transfer of heat from your coolant.

A much better idea is to utilize one of the many products on the market which will safely clean your radiator for you, such as Gunk, Prestone, or Bar's Stop Leak flushes (there are many more, these are just examples). Following their directions here will save you not only time, but money as well. Using the above cleaning agents may, or may not, have adverse affects, but why chance it when you can utilize a product which is specifically designed to clean your entire cooling system and will not harm it in the process.

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I will search the local shops to find out what is available in this part of the world. Definitely I will be able to find something when I ask for a radiator cleaning fluid. – Masroor Aug 1 '14 at 14:35
I'm sure there is something in Bangladesh. If you can get anti-freeze, you should be able to get flush. If, as a last resort, go to a dealership and ask them if you can purchase a flush. There must be some type of auto parts store near where you live. You might find good results in just draining your current coolant, replacing it with straight water, running it to temp, letting it cool, then draining this. Do this about 3 or 4 times and your cooling system should be fairly clean. On the last one, drain as completely as possible, then refill with the standard 50/50 mix of water/anti-freeze. – Pᴀᴜʟsᴛᴇʀ2 Aug 1 '14 at 14:49

A big fat NO. I'm a corrosion engineer, trust me you don't have to play with the PH of solution and alter (generally increase) the corrosion rate of your radiator. Corrosion rates can raise up to like your radiator vanishing in 6-8 months.

PH highly influences corrosion of copper that's why the coolant has a inhibitor (chemical specie) that controls the PH according to conditions of pressure, temperature, and PH of fluid. It keeps it in the favor of radiator material, ie: copper, etc.

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Welcome to the site and thank you for answering. Links and references are appreciated when answering questions. Also, Internet etiquet suggests one should refrain from using all CAPS when corresponding ... It's no different here. Thanks! – Pᴀᴜʟsᴛᴇʀ2 Mar 14 '15 at 10:48

'Cleaning' radiators is very much a thing of the past. Modern rads are made of alloys and plastics which are no longer cleaned internally. Introducing any sort of caustic cleaner into your cooling system has the very real ability of destroying seals and gaskets and bearings in the system as well. Introducing products like a leak stopping formula only goes to block the passages of your system, especially the heater matrix. Blocked rad means a new rad.

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Your advice will come in handy when I get my next car. For my present one, cleaning is applicable. – Masroor Aug 2 '14 at 13:33

If you must use household products, the least aggressive I've found is good old baking soda. It's just gritty enough to "sand" off the buildup inside the radiator and, unlike vinegar, when mixed with water, baking soda increases in volume to get into all the voids.

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