Generac — Coolant Draining and Adding
Maintenance · Cooling system
From a Generac service manual covering: CAC478, CAC480, SQR480. Check it applies to your exact model before use.
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Before you start
- Do not remove the radiator pressure cap while the engine is hot or serious burns from boiling liquid or steam could result.
- Ethylene glycol base antifreeze is poisonous; do not siphon with your mouth.
Procedure
- Remove the pressure cap of the expansion tank.
- Connect a container under the radiator; remove the radiator outlet hose or open the radiator drain plug.
- Before adding coolant, check the radiator drain plug is closed and pipelines are connected and tight.
- Remove the pressure cap and add coolant slowly by the expansion tank filler.
- Keep adding coolant until the level reaches the maximum line and install the filler cover.
- Start the engine and idle until normal working temperature; add coolant if the level drops quickly.
- Stop the engine and let it cool completely; remove the pressure cap, check and fill coolant to the maximum line.
Tools required
- Container Amazon
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Source: Generac service manual. Steps and values are as documented; always cross-check against the official manual and any later revisions for your exact serial number before servicing.