Using the GE-52079 Coolant System Fill Tool

The supercharged 6.2L V8 engine (RPO LT5) in the 2019 Corvette ZR1 uses five charge air cooling radiators. Behind the front fascia, there are three charge air cooling radiators; one in the center and one in each corner. There are two more within the supercharger assembly (Fig. 6). Two on-vehicle electric pumps are used to pump coolant to the driver-side port and the passenger-side port of the supercharger.

Fig. 6

The coolant is drained by disconnecting the hoses at the respective charge air cooling radiators. The coolant is filled via quick connect tee fittings at the inlet ports of the supercharger. The LT5 charge air cooling system does not have a remote reservoir, surge tank, or drain plug.

Any time that the supercharger’s cooling system is serviced, it must be properly drained and filled using the following special tools:

  • GE-26568 Coolant and Battery Fluid Tester
  • GE-47716 Vac-N-Fill Coolant Refill Tool
  • GE-52079 Coolant System Fill Tool
  • GE-52079-10 Coolant System Fill Tool Adapter

The GE-52079 Coolant System Fill Tool (Fig. 7) and GE-52079-10 Coolant System Fill Tool Adapter (Fig. 8) are required to fill the charge air cooling system on the Corvette ZR1 (LT5) and Z06 (LT4). The Vac-N-Fill machine must be used in conjunction with these tools.

Fig. 7


Fig. 8

The GE-52079 Coolant System Fill Tool (Fig. 9, #1) is designed to purge all air from the system after service, which will achieve a complete fill. This is very important because any air left in the system will have detrimental effects on vehicle performance (i.e., loss of horsepower).


Filling the System

The GE 52079-10 adapter (Fig. 9, #2) plugs into the coolant system quick connect fill port tee. It does not matter which of the fill port tees are used; however, the arrow on the adaptor must point out and away from the engine (Fig. 9, #3).

Fig. 9

The GE-47716 Vac-N-Fill Tool is required to pull the system into a vacuum and serves as the method for adding coolant into the GE-52079 Coolant System Fill Tool. The GE-47716 Vac-N-Fill Tool should be filled with the proper mixture of coolant and clean, drinkable water (refer to the appropriate Service Information procedure).

After the system is initially filled using the Vac-N-Fill method, it is necessary to cycle the auxiliary coolant pumps. The coolant is circulated using the auxiliary coolant pumps by commanding the pumps on using the GDS 2 diagnostic scan tool (be sure to connect a battery charger). As the pumps begin to circulate coolant, the GE-52079-10 adapter diverts a large quantity of coolant into the GE-52079 clear reservoir. Air bubbles are released from the coolant and exit at the top of the reservoir through the loosened fill plug.

During the de-aerating procedure, if coolant flow has stopped, it is because the charge air cooler coolant pumps have shut off. Both coolant pumps will shut off if they start to draw air (sensed by pump RPM). If this occurs, repeat the Vac-N-Fill procedure to pull the system into a vacuum to remove air, followed by allowing the pumps to push coolant into the GE-52079 reservoir.

Coolant will continue to enter the GE-52079 reservoir and de-aerate the vehicle’s cooling system. The measurement gauge on the side of the GE-52079 reservoir can be used to monitor the decreasing level of the coolant inside the reservoir. When the system has stabilized at a specific level within the reservoir and no more air bubbles are visible, the system is considered full. (Fig. 10)

Fig. 10

After the system is considered full, shut down the pumps and close the valves on the GE-52079 hoses to prepare the tool to be disconnected from the vehicle. The shut-off valves on each hose and on the tool reservoir help avoid leaking any residual coolant remaining in the reservoir after service is completed.

– Thanks to Chuck Berecz, Tracy Lucas, Austin Leopold and Christopher Semanisin

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  1. A note from GM Service Engineering regarding the proper fill procedure:

    It is critical that the vehicle specific service procedure for each vehicle be followed as written in the Service Information to ensure that there is no remaining air pockets within the cooling system. For Charge Air Cooling (CAC) systems without an overflow/surge tank, there is no feasible way to determine if air is in the system without the service tool’s translucent tank visually indicating the lack of air. Even a small amount of air can have a major impact on performance. Furthermore, CAC systems with or without an overflow/surge tank need to use the Vac-N-Fill method prior to any further filling/bleeding. Bench and on-vehicle testing has proven that static filling is not feasible on these systems given the complexity of the hose routing and cooler designs. Our service engineering department is constantly working with product engineering to ensure we have an efficient and accurate cooling system fill process for dealers. Thank you for your feedback.

  2. Sean Fitzgerald says:

    Thank you for a Very timely article. I currently have A 2019 Z06 in from our body shop that had hit a Deer. Our Body shop had refilled cooling system but were unaware that supercharger had separate cooling system. Upon inspection found it empty, looked for these special tools to refill and found we did not have them. I have found that a DEF funnel works great on a coolant jug and fits the inlet perfectly so used it to refill system. Thanks again for this information.

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