Tech Tip: Leak Preventative Additives

2011-2017 Chevrolet Volt; 2014-2016 Chevrolet Spark EV, Cadillac ELR; 2016 Chevrolet Malibu Hybrid

The cooling systems in these models use very small orifices in multiple areas (heater core filter, heater core, thermostat, radiators, heater plates in the HV battery cells, etc.) for the cooling systems. Leak preventative products or other additives used in the cooling systems will clog the small orifices and reduce the flow of coolant. Disruptions to the cooling systems can result in multiple part replacements including the entire HV battery. 

The flushing process described in the appropriate Service Information is for maintenance and part replacements only. It does not provide an adequate flushing procedure to remove the leak preventative product from the small orifices throughout the two cooling systems.
If a leak preventative product or additive has been used in the:
  • Passenger compartment heater system – the heater core, heater core outlet filter (if equipped), thermostat and coolant must be replaced. The entire passenger compartment heater system must be removed to thoroughly flush/clean the leak product/additive.
  • Hybrid/EV battery pack cooling system – the coolant and Hybrid/EV battery pack may have to be replaced due to Diagnostic Trouble Codes set for clogged orifices, overheating, and/or isolation faults. Once the HV battery is replaced, the entire HV battery coolant system has to be removed to thoroughly flush/clean the leak product/ additive.
  • Hybrid electronics cooling system – the electronic control modules may have to be replaced. The entire hybrid electronics cooling system must be removed to thoroughly flush/clean the stop leak/additive.

If the leak product/additive cannot be properly flushed/ cleaned or it can’t be determined if the product was completely removed, then the part(s) must be replaced. If any of the leak product/additive is left behind, the vehicle may experience a repeat issue when the system is filled with coolant.

The passenger compartment heater, Hybrid/EV battery pack cooling, and hybrid electronics cooling systems require a 50/50 mix of GM DEX-COOL® and de-ionized water. This mixture is available in a pre-mix with bitterant. Do not use tap water or distilled water.

Need assistance? Contact one of our Technical Assistance Centre agents at 1-800-263-3526 prompt 2.