Determine 50/50 Mix or Straight Coolant?

[asinor]

I'd like to see this rating in some factory literature. Yes, running higher pressure allows the heat to increase before boiling. That is the point of it. Most people prefer to have a hot, running engine over one with most of the coolant boiled out of it on the side of the road.

I run a 20 psi cap and have yet to damage any factory cooling system parts.

Agreed. As long as it is not boiling, it is still absorbing heat.
Parts don't break/warp when the metal gets to 212 degrees, they warp when the water boils and there is zero cooling in a specific location. That location is usually at the top of the system where the vapor gathers and the metal is not being cooled by the liquid (IE the heads). Head gaskets blow because the pressure increases rapidly when the water transitions from liquid to gas.

 

[toddz69]

About measuring the galvanic voltage, click this & read the caption:

Similar to the instructions that Ron Davis sends with their aluminum radiators - although they specify 0.3V as the upper limit.

Todd Z.

 

[Steve83]

I run a 20 psi cap and have yet to damage any factory cooling system parts.

If his cooling system is as well-maintained as yours, it'll probably be fine. But what are the chances? 13psi works, and is much safer for a 40-y.o. vehicle.

As long as it is not boiling, it is still absorbing heat.

If it IS boiling, it's absorbing heat even faster.

Parts...warp when the water boils and there is zero cooling in a specific location.

Actually, they warp when they're heated above their eutectic point & then cooled unevenly. I've driven my truck with no coolant for hundreds of miles and didn't hurt it (but it's an I6, and it was a cool night, and I was cruising on the highway).

Head gaskets blow because the pressure increases rapidly when the water transitions from liquid to gas.

That's totally wrong. It's not like gunpowder or C4 - it's just boiling water, which does NOT create a significant/sudden pressure rise. The cap vents it. It may take a second or 2 for it to vent enough to get back down to its rated pressure, but it doesn't shoot high enough to blow a steel-reinforced gasket in that brief time. The gaskets blow from rust (due to poor coolant maintenance), warped head/block, or head bolt problems.

 

[Timmy390]

50/50 Prestone "any make any model" Freeze point -34F boil point 265F
70/30 prestone "any make any model" Freeze point -84F boil point 276F

Choose how cold it gets in your area and mix accordingly.

Tim

 

[Jeff10]

Hi Steve,

13psi is what the heater core & other cooling system parts are rated for, and running a higher-pressure cap just lets the engine run hotter before the coolant boils (which makes overheating more likely). So think again about running the higher pressure.

There are plenty of special coolants, but if you change normal coolant on the recommended schedule (like almost NOBODY does), it's fine for Al radiators.

About measuring the galvanic voltage, click this & read the caption:

Thanks for the information.

I am going back to correct my recent post... the article referenced DC voltage, not resistance. My bad.

I may consider a lower pressure cap; but, that depends on the effectiveness of this new radiator and the other changes that I have made. If the Bronco is still running hotter than I'd like (above 220 F), I will take my chances with a lower rated cap. If I can get relief from the higher operating temperatures, I will give a lower rated cap a try.

I don't recall seeing special coolant for an aluminum radiator in my trips to the auto parts store... so I thought I would ask.

Thanks

Jeff

 

[Jeff10]

Hey Guys,

Thanks for all the input.

I'll report back on the voltage reading once I correct the leaking thermostat housing.

Take Care

Jeff

 

[asinor]

If it IS boiling, it's absorbing heat even faster.

True , But only If there is water there to boil off that hot part
If its a metal part exposed only to water vapor but not liquid water, its going to get very hot very fast. Water vapor is less dense than water and does not have the ability to transfer heat as well as the same volume of water. Each molecule can absorb the same amount, there are just far fewer of them in contact with the metal and each other.

Actually, they warp when they're heated above their eutectic point & then cooled unevenly. I've driven my truck with no coolant for hundreds of miles and didn't hurt it (but it's an I6, and it was a cool night, and I was cruising on the highway).

Again no where near 100 C, closer to 550. Not really hard to do when the combustion temperature is higher than the melting point of cast iron.

That's totally wrong. It's not like gunpowder or C4 - it's just boiling water, which does NOT create a significant/sudden pressure rise.

You are right, I misspoke. Its not a sudden rise in pressure like an explosion, its the lack of direct liquid cooling of the head which causes the metal to heat rapidly, warping of the head and/or compromising the head gasket, then it leaks due to the pressure caused by the water vapor trying to take up 1700 times the space as the same amount of water and having a new path of least resistance.

 

[69red]

and always use distilled water or demineralised water if you are mixing it yourself. never use tap water in an Al rad.

hard water will rot or plug up that sweet new Al rad

 

[Steve83]

I don't recall seeing special coolant for an aluminum radiator in my trips to the auto parts store.

The cheapo parts stores may not carry them - they're mostly for VERY new imports, like blue BMW coolant (also used in some Land Rovers), and several other types. Their cost doesn't justify their performance unless you're putting it into an expensive vehicle with a warranty, which is why they're not common in parts stores yet (and may NEVER be).

True , But only If there is water there to boil...

Of course, it can only boil if there's water there to be boiled. %) But coolant doesn't hit cast iron that's at 550C - it hits cast iron at 230-250F, boils, and the steam vapor almost immediately condenses back into scalding-hot water. It has to boil for a while before the block/heads can get significantly hotter. But boiling actually cools them much faster than flowing coolant does. The journals just aren't designed for it to work that way in steady-state, which is why you can't drive for long with boiling coolant.