Alco 636 Demonstrators

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  • Member since
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Alco 636 Demonstrators
Posted by cessna 310 on Saturday, January 4, 2020 1:36 PM

I was reading in the latest issue of "Trains & Railroads of the Past" about an incedent that happened to one of these units when it was on the NYS&W in the early part of the decade. The article sated that the automatic water drain failed when the engine shut down and the engine block subsequently froze and serious damage was done to the cooling system and radiator.

My question is this: Why wasn't the cooling system equiped with anti-freeze?

 

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Posted by Overmod on Saturday, January 4, 2020 3:59 PM

cessna 310
My question is this: Why wasn't the cooling system equiped with anti-freeze?

These large engines often weren't equipped with glycol or other antifreeze, although there were, sometimes, additives in the water.

On an EMD 2-stroke(567/645/710), which uses scavenge air, little leaks can produce bad consequences over time, so restricting the contaminants in the cooling water is desirable.   A railroad might standardize its cooling requirements to whatever chemistry the radiators best 'see' with respect to plugging or corrosion, and simply size the radiators to have adequate capacity without azeotropes or excessive pressurization of the coolant to suppress nucleate boiling.

There is also a considerable cost involved in 'that much antifreeze' per engine, which has made it less likely until comparatively recently that higher-performance coolant would be used or even specified.

Some railroads used circulating water heaters to keep engines warm in cold temperatures; others used timed or continuous idling when that was politically permissible.  The coolant-water dump represents a lowest-cost safe alternative and you see it implemented on a very wide range of locomotives (Centennial 6936 very prominently has warning indicators for the 'dump' system with the engine controls.)  Note that on a modern engine that does use antifreeze mix, you no longer have the option to dump even a small amount, as any intentional spillage is no longer tolerated by the EPA. 

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Posted by cessna 310 on Sunday, January 5, 2020 12:36 PM
Thank you for taking the time to reply, the information was enlightening. Sky King
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Posted by beaulieu on Wednesday, January 8, 2020 5:12 PM

Also larger diesel engines like those used on railroad locomotives have significant thermal expansion. When the engine is shut down parts cool at different rates creating coolant leaks into the cylinders and the oil pan. Antifreeze products tend to destroy the lubricating qualities of motor oil which will quickly lead to bearing failures, and expensive repairs. 

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