Many people think that all cooling system antifreeze products are the same, except some are methanol based and some are glycol based. Not so! In newer automotive applications, silicates are needed to protect aluminum engine parts and radiators from corrosion, and are used in virtually all antifreeze mixtures in varying forms and amounts.
Eventually, silicates are supposed to drop out of the coolant mix, and as long as they do so at a controlled rate, they work quite well. However, over time, the “soup” of chemicals, impurities, and corrosion by-products in a cooling system can start to behave in ways difficult to analyze or predict. When silicates begin to drop out too rapidly, they build up and form a gel.
A number of things can start this process: high silicate levels from incorrect antifreeze concentrations or improper use of coolant additives, impurities in very hard water, and severe engine temperature swings.
The main effects of the formation of this silicate gel are clogging of radiator and heater cores, and engine overheating. Silicate gel buildup greatly reduces heat transfer from the engine castings to the coolant. When the gel coats the temperature sender, engine overheating can take place without notice. Silicate gel also carriers abrasive particles to the water pump, where it wears away pump seals causing leakage and failure.
Unfortunately, there are few effective methods for cleaning the gel from an already-clogged system. Radiators must be removed and sent out for a thorough cleaning. The engine must be flushed with a caustic solution. The gel is not water soluble, so flushing with water alone will not work.
John Deere offers a Low Silicate Antifreeze, part number TY26575, designed for use in heavy-duty engine applications that will avoid the gel problem.