When I first walked into a foundry in the late 60's and watched them doing core assemblies, I thought, "This is simple, I can master this S*** in a week. Oh really? I still learn something new every time I walk into a foundry, and I have now done foundry engineering and tooling for 40 odd years. Nothin' to it. Mummert got a REAL lesson with the heads, but then i wish  I could understand what he knows about airflow. 

Frank/Rebop

Bristol, In ( by Elkhart) 

I too am personally beginning to think that the "pH" variance of the coolant - and the incidence of what is called "electrolysis" are one and the same problem. Just as battery acid induces current flow by "stripping electrons" from the battery plates - low pH coolant starts stripping its containment (engine block, radiator, exposed aluminum ....). The tech suggestions to make the solution base (pH 7.0+) just keeps the acid at bay. The suggested upper limitation of pH (10.5) avoids the situation where the alkaline solution starts slipping over the edge toward caustic - which can really get after the aluminum.

Using a radiator cap with a sacrificial anode would give you a visual indication that something was up. But erosion of the anode would also indicate that you need to do something - not just change the cap.

One tech source suggested use of a digital volt meter to test for "electrolysis" conditions. Suggested: run engine to temp with radiator cap off. With the negative probe on the lowest ground (battery post in most cases) and the positive probe immersed in the hot radiator fluid (not touching anything but fluid), check for DC voltage. If the voltage is as high as .3 vdc  - it suggested draining, flushing and refilling with new coolant. Which usually would cause the coolant solution to go to neutral pH (distilled water for instance) or above (to 10.5) for pure antifreeze.   

 
 Steve Metzger       Tucson, Arizona

There's a company, can't remember the name, that advertises Radiator Caps that have an Anode suspended from them. Would that be beneficial in reducing electrolysis?

Paul

Steve,

        I'm sure the pH levels were concocted based on the use of some form of anti-freeze. I don't run anti-freeze in the F code car, it never goes out when the temp is much below 40. Also race tracks have a dim view of Glycol on their racing surfaces. I had not thought about the relationship of pH to conductivity, somebody will have to explain that to me. This conversation started out based on electrolysis, and wound up discussing erosion from acidic or alkaline based coolant. You may be on to something, but I'm not sure what. Aluminum does not like alkaline contact, but it absolutely hates acidic conditions. Maybe much of what we THINK is electrolysis is actually deterioration from reactions to the coolant. To me it makes no sense to run a pH that alkaline with either cast or aluminum, I'm going to ask some people some questions and see if I can come up with an answer.  

Frank/Rebop

Bristol, In ( by Elkhart) 

Steve,



While straight water/additive may well be the most efficient coolant, the boiling point is pretty low. I have gone to 70% Amsoil propylene, as I am running zero pressure these days (leaky head gaskets). Unlike standard antifreeze, it won't ruin your bearings if it gets into the oil, it has self-sealing properties, and the overflow puddle won't poison my cat. Pricey though.



Anyway, the 70% runs as cool as any other mix I have ever used, so I don't miss the pressure. If it wasn't for my open-air conditions, it would be as close to "permanent" as possible. I read where some diesels run 100% and never have to change/flush in a closed system.

6 VOLTS/POS. GRD. NW INDIANA

steve

after i posted i remembered acid rain something we dont think a lot about here but we do get it every now & then.

moz. geelong victoria australia.

graduate 1980, bus, truck, car, hot rod, boat, submarine, hovercraft, hydrafoil, firetruck, mobile home, jet, helicopter, cruise ship, motorcycle, bicycle, santa's sleigh, clock, alloy bullbar, alloy fuel tank, lens, dr who's tardis, matter - anti matter warp drive buffer & y-block lover

Frank -

Nearly all of the coolant tech specs you can find are based on the required protection of diesel engines in fleet vehicles. The items they are trying to protect are exactly the same as we wish to protect in our gas engines. Iron blocks - pump seals - aluminum housings - copper or aluminum radiators ...... They never mention electolysis - only control of solution pH.

Virtually every tech source I found recommended that the finished coolant package be alkaline - not neutral. In fact, the numbers were pH on the order of 9.5 to as much as 10.5. This would make the solution somewhat naturally resistant to low level electrolysis correct?

Every tech source also recommended the use of distilled water (pH 7.0/7.2) to minmize the entrance of any extraneous elements that produce scale and also "start" the solution at neutral pH.

The use of tap water (with chlorine) was discouraged because it interacts with glycol antifreeze and becomes acidic (creates chloride compounds). It also contains solution elements that leave scale.

50/50 was the preferred mixture of antifreeze to water - but glycol antifreeze apparently has a pH of 10.5. When used at this ratio with distilled water the pH of the solution only reaches 8.75 - not up to the recommended 9.5/10.5. I don't have a chart at hand but 50/50 might not completely do the trick in wintertime Canada (lower than -34°F). 

Nitrite/nitrate additive packages were recommended - the NAPA coolant test strips showed 1200 ppm as a preferred level. This additive apparently resists rusting of iron in particular when subjected to high doses of sonic vibration.  

My bird has its cooling system filled with distilled water and a Prestone additive (no antifreeze) ph is 7.0 - just as you were thinking - so was I. But the testing kit I bought from NAPA indicates that the nitrate level is low (by about 50%) and the pH is low as well. A second bottle of the additive will probably fix the nitrate level OK - but what can be used to raise the pH of the solution? (short of going to an antifreeze mixture). 

 
 Steve Metzger       Tucson, Arizona

AZ,

     A ph of 7 or 7.2 is basically neutral. That's what I would shoot for. Are you confusing acidity or Alkalinity with electrolysis? I'm pretty certain if we simply follow the recomendations of the newer Aluminum headed vehicles we'll have no problems. I would suggest a rust inhibitor be used on your 50 year old cast iron block after it's flushed thoroughly. 

             

Frank/Rebop

Bristol, In ( by Elkhart) 

Hey Moz - We yanks have to look out for "acid rain" over here - eastern US has been getting some pretty low pH numbers according to the USGS.

Found other web references to the pH of radiator coolant late last eve - one stated that the "coolant should be a mixture of distilled water (pH 7.0/7.2) and a glycol based antifreeze (pH 10.5). With a 50/50 mix this nets an unadjusted pH value of approximately 8.75. This is low as the optimum value should be in the neighborhood of 9.2/10.2 ......." and after this grand revelation, they never suggested any method (or chemical components) of "adjusting " the mixture. I think we need to know what this adjusting chemical is - ideas or personal knowledge anyone???

Later I found some comments about a simple concoction used specifically for an aluminum headed small chebbie: 5% distilled water and 95% antifreeze - with interesting reasoning applied. First - the aluminum heads are much more efficient at transfer of heat and can successfully be used with the nearly straight antifreeze - whose molecules don't absorb heat as well as water. Second - the concoction has just about exactly the right optimum pH to avoid corrosion difficulties. This set-up will protect the heads and aluminum parts OK I'm sure - but freezing might be a different issue as straight antifreeze isn't as good at low temp protection as a water mix.

 
 Steve Metzger       Tucson, Arizona

you could use rain water as well i know a few people that swear by it & wont use anything else ive used it in the cooling system on my rotary engine.

moz. geelong victoria australia.

graduate 1980, bus, truck, car, hot rod, boat, submarine, hovercraft, hydrafoil, firetruck, mobile home, jet, helicopter, cruise ship, motorcycle, bicycle, santa's sleigh, clock, alloy bullbar, alloy fuel tank, lens, dr who's tardis, matter - anti matter warp drive buffer & y-block lover