No worries about using the tap water if that's what your past practice has always been - think of all the years that people have been doing that - and it has worked well enough as is!   But.....the lime coating you find in many of the old systems we open up.......it got there by virtue of that (common) service practice. Heat transfer must be somewhat reduced by the coating - but how much? Who knows? Can't be too terribly bad, all of the motors I've torn down over the years had it to varying degrees.....everybody else will attest to the same. And a lot of those old motors went a zillion miles.

If you want to do something good for your system - get some of those "litmus paper"  check strips and be darned sure the mixture doesn't check out to be too acid (pH of 7.0 or under).

Here in Tucson - our city water system delivers a product that is very nearly stone on a good day - and woe be to the guy that washes his car in the stuff!!!! Motors that spent their whole life here must look somewhat like a cavern inside the water passages. They are telling us that as the water supply drops out here - the amount of "entrained solids" is going to double in the next five years.

.   

 
 Steve Metzger       Tucson, Arizona

We use regular tap water here at the shop for new radiators. I have heard of using distilled water. BUT, I hope I didn't boo boo here too badly! I used tap water and mixed it with antifreeze.

Sorry, I should have typed "DE-ionized water".

I'm in a bit over my head here (slept through high school chemistry, teacher's father owned the gas station I lived next to and passed me anyway), but I think pure H2O (zero Total Dissolved Solids) is PH neutral. But, just like nature abhors a vacuum, it doesn't like pure water either. It will suck metallic ions out of any metal it comes in contact with, and then it's PH would likely depend on whether those ions were base or acid, I suppose. Typically, softened water contains considerable sodium (likely not good for iron engine blocks), and is usually still much higher in minerals than distilled/de-ionized water. I suspect the distilling process produces water chemically different in some way from that made by a de-ionizing method, but from there on I'm largely at sea.

6 VOLTS/POS. GRD. NW INDIANA

I guess I've never seen any "mineral hungry/ionized water" - especially if it was specifically treated to be neutral Ph......

Seriously - all of the truck fleet maintenance radiator check strips I've had my hands on over the years - turned out to be litmus paper. The fleet management people simply wanted to regularly check and adjust the acid/base level of the radiator coolant mixture. I've read some material that suggested pushing the Ph a bit deeper into the "base" numbers if you were running aluminum cylinder heads - and that would probably be a very good idea. The premixed coolant for my old Z28 (aluminum LS1 motor and aluminum radiator) came premixed from GM as a base solution. I'd have to hunt down the tech spec's  - but I think it was maybe two steps into the "base" scale. 

Does your RO filter result in "soft" water? If you can boil away a pan of it and leave no scale - its probably free enough of mineral content to subsitute for distilled water in a radiator. I used to know the right number to ask for at the NAPA store - to get the litmus test strips used on truck radiators - but can't find it tonight. The lab method of suppressing the "carbonic acid" (made by exposing the water to carbon dioxide) - adding a drop of ammonia per gallon might apply to the filtered water as well. 

Apparently a lot of the newer diesel technology revolves around "anticavitation" additives - a complexity we really don't use on the gas engines. This ad is  for some of the 'old fashioned" testing strips.... http://www.cooltrak.com/

 
 Steve Metzger       Tucson, Arizona

Steve,



What's your take on the mineral-hungry/ionized water subject? I have an RO filter for drinking water, and have always wondered if it's worth buying distilled at the store when my free RO supply is nearly zero TDS? Would the addition of numerous aluminum cooling system components be significant (dissimilar metals/electrolysis/etc.)?

6 VOLTS/POS. GRD. NW INDIANA

Just two more cents.....use the 7 lb. cap. Until the system signals otherwise - by puking a lot of water and steam - there is little reason to crank up the system pressure. Are you going to add an overflow tank? or use the "traditional" mid-fifties Ford volume control which is not filling the upper radiator tank completely full? Early trials at this may (obviously) cause some amount of expansion overflow - but you will find a comfy level that works for everyday use.

Use store bought distilled water to mix up your coolant - its cheap and doesn't leave lime deposits. While it should be Ph neutral (which is what you want) - it is often found to be (very) slightly acidic due to absorbtion of atmospheric carbon dioxide. Professional labs fix this by adding one drop of household ammonia per gallon - which works for radiator water too.

If you don't use anti-freeze in your coolant - use one of the over-the-counter additive packages to provide corrosion and pump seal protection. 

 
 Steve Metzger       Tucson, Arizona

If you run a good coolant year round, you don't need the extra pressure to raise the boiling point. When these things were new, it was common to run anti freeze in the winter and clear water in the summer.

Kenneth

Fredricksburg, Texas

Each pound of pressure raises the boiling point of the coolant by 3 degrees F.With a 7 pound cap it would be 21 degrees.with the 13 lb cap it would be 39 degrees.With your new rad you could go to 13 pound cap safely BUT it may cause leaks in the heater core as it is weaker due to age.Go with the 7 as most of the other members seem to do.

  

Thanks for the reply! This is a brand new radiator, 3 core. So, would a 7 lb be ok with it? Is there any advantage to using a 13 lb cap? OR just be safe an dstick with a lower pressure one?

Thread dealing with cap pressure.

http://www.y-blocksforever.com/forums/Topic48649-3-1.aspx?Highlight=cap+pressure

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