Transmission fluid as coolant...

[Externet]

Hello all, am new here.
As titled; long ago I got comments about it but with no solid rationale against; perhaps some knowledgeable members here can shine some open mind extra light.

As replacement of water based coolant in ICE engines, transmission fluid can:
- Eliminate rust progress or prevent it,
- Eliminate boiling at operating temperatures,
- Eliminate pressurized circuits,
- Eliminate specialized orange, green, whatever coolants,
- Increase efficiency with hotter combustion if wanted by thermostat choice,
- Even used transmission oil at $0 is good enough,
- Better heat transfer wettability
- No more blown head gaskets perhaps ?
- What else ?

The thermal conductivity properties of thin oils as transmission fluid are near the same as water, cooling is what mostly does in a transmission, which can run much hotter than an engine.
Its viscosity is not far from water based coolant.
Some other light oils are meant for cooling (transformer oil as an alternative)

Now, the considerations to take care are
- Hoses should be oil resistant, not the kind meant for just hot water, obviously.
- There is some rubber inside engines; there is rubber inside transmissions too.
- What else ?

Has anyone done it ?
In events were the transmission fluid has leaked into the radiator, what engine harm was proven to an engine with its 'normal' type of rubber parts ?

Thanks,
Miguel

 

[d00df00d]

How do you define "near the same" and "not far"?

Small deficiencies in performance, if there are several, can add up fast...

 

[Paul56]

Originally Posted By: Externet

In events were the transmission fluid has leaked into the radiator, what engine harm was proven to an engine with its 'normal' type of rubber parts ?


The problem is more severe the other way around... coolant getting into the transmission.

 

[Chris71]

If that tranny fluid leaked onto a hot engine, you could have a heck of an under-hood fire. Ever see an old drag photo of when an automatic car blows the tranny and that fluid hits those hot headers? FIRE!

 

[onion]

I've wondered about the same thing, myself. Not sure how well a water pump impeller will move ATF... nor how well ATF conducts heat.

And, yes, there's the rubber issue. Oil resistant radiator hoses are going to be hard to come by. But you could probably make some silicon hose work. It's pretty expensive... but oil resistant.

And you'd need to be pretty familiar with the engine in question to be sure that you've replaced any rubber seals with something that's oil resistant.

Yep... it could be done if you wanted to spend the time and money. And I'd be interested to hear about the results.

But personally, I'll just stick with G-05.

 

[Externet]

Hello and thanks.
The 'not far' viscosity for transmission fluid searches show 3.5 centiStokes; 15000cP-Brookfield; 0.028Pa
The 'near same' thermal conductivity figure for it was hard to find a while ago, but remember something around 90% of water; when I can confirm this data buried in another hard drive, I will post.

Can an expert give an opinion if those figures would be acceptable ?

Edited-added:
Another goodie forgotten on the original post is
-No freezing

 

[d00df00d]

Those numbers certainly look good on paper, but I would think that the slight increase in viscosity and decrease in thermal conductivity are enough to incur significant additional pumping losses and higher pressures.

Also, as we have begun to point out, ATF is much less friendly in many ways than coolant when leaked.

 

[Kestas]

Thermal transfer depends on more than viscosity and thermal conductivity. It also depends on heat capacity of the fluid.

Intuitively, I find it hard to believe that ATF and traditional coolant have the same viscosity. Anybody who has drained each of these fluids can attest to that.

Conversely, if someone designed a system that was cooled by ATF, I believe they would have found it a godsend to switch to water-based coolant.

 

[onion]

I think ATF may be a little thick.

Maybe you should try diesel fuel.

 

[edhackett]

Indeed, water has over twice the heat capacity of light oil. About 4.2 vs 2. Half is not "near the same" and "not far" in my book.

http://www.engineeringtoolbox.com/specific-heat-fluids-d_151.html

Ed

 

[Externet]

Correct-
Comparative data at page 7 here:

http://www.lawrencepumps.com/documents/buffer and barrier fluids.pdf

Shows the transmission fluid not as promising as I thought.

An engine and its cooling system would have to be redesigned to use oily coolant.

Thanks

 

[edhackett]

Actually, your idea is not totally without merit. It has been done. Now, the size of the system would have to be too large to be practical.

The Rumley Oil Pull is an example from the early 1900's. Notice the large exhaust stack/radiator. The exhaust is routed into the top part of the stack, which by venturi effect pulls cool air in the bottom and through the bottom mounted radiator.

http://www.youtube.com/watch?v=qoUgUTyfiWU&feature=related

Some BMW and Suzuki motorcycles use a combination of air and oil cooling.

Ed