Integra - Coolant issues and questions...

I have an Integra 94 and live in Los Angeles area. When I was on vacation, I let my nephew used it for a few weeks. On my return, he told me that the radiator had developed a leak, but he had been
refilling it using just water (not coolant). The car was running fine and no overheating was observed (other than losing about 1/2 Qt of coolant every 50 miles). My question is what exactly does the coolant do, other than keeping the boiling point higher than water and freezing point lower (hence the anti-freeze function)? Does it also prevent the engine from rusting? I have heard that Integra has an aluminium engine. What does the coolant do in this case? Would a few weeks running with greatly diluted coolant harm the engine?
Thanks. Need to know
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If he was using distilled water you're probably in pretty good shape. The water pump lubricants and corrosion inhibiters should have carried you over just fine for this short time.
If he was using tap water, you want to get that out of there right away. The minerals in tap water will deposit themselves in the radiator and will corrode the alloy parts, in spite of the remaining antifreeze. A few weeks is no big deal but you don't want to stretch it into a few months.
Mike
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Coolant: the water Antifreeze/corrosion inhibitor: the stuff you add to the water.
If the coolant level has been allowed to get low (as in your case), you can have localized overheating of head and the top of the cylinders. This can contribute to early head gasket failure. Localized overheating will not manifest itself on the temperature gauge.
Antifreezes LOWER the boiling point of water. Pure water absorbs heat better than that with antifreeze added. The RAD CAP has the job of controlling boiling, not the antifreeze. Cars in warm climates can run plain distilled water with just an anti-corrosion additive.
The Integra's block and head (as well as many other parts) are all- aluminum, and WILL corrode in the absence of corrosion inhibitors. Your cylinders are iron, of course. Heat, and the oxygen in the water, are the instigators of corrosion. Antifreeze contains anti-corrosion inhibitors. These inhibitors coat the surfaces inside the passages where the coolant flows, thus keeping oxygen away from them and preventing corrosion. With time, these coatings erode, and the chemicals in the fluid can even become corrosive themselves, which is why you need to change your coolant every few years.
In your case, there should have been sufficient residual corrosion protection that corrosion should not be an issue. Yet.
As Mike Pardee says, if you've been using tap water to top the rad up, that's a bad thing if done for longer than a stop-gap measure. With the leak fixed, you need to get ALL the old stuff out of there, and replace it with Genuine Honda premix, or a compatible Long Life antifreeze and DISTILLED water. Honda premix is the very best you can use. And don't forget to open the heater control valve and remove the block drain when performing the fluid replacement.
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TeGGeR

The Unofficial Honda/Acura FAQ
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Thanks for the advice, Tegger and Mike. Appreciate it. I have been thinking about doing the replacement myself. I can find a "new" replacement (brand Koyo), but the book that I read advised me to just try to take it out to the repair shop to see if they can repair (weld, glue, whatever) my original Showa radiator first. It said that my "repaired" Showa should be even better than the new replacement. What are you guys' opinion?
Any particular place on the web that would have a good price on a new replacement?
Thanks. Synergy
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Forget repair. It's not worth the risk.
For $20 you can get a decent aftermarket aluminum dual-core at your local NAPA.
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Read: "About $200"! NOT "$20".

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You can try suppliers listed here, who offer both OEM and aftermarket: http://www.tegger.com/hondafaq/online-parts.html
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TeGGeR

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