Westerbeke 90A FOUR — Changing Coolant

Maintenance · Cooling System

For the Westerbeke 90A FOUR, from the Westerbeke operator's manual.

Procedure

1. Drain the engine coolant by loosening the drain plug on the engine block and opening the manifold pressure cap.
2. Use the drain petcock on the heat exchanger to help drain engine coolant.
3. Flush the system with fresh water.
4. Replace the engine block drain plug and close the heat exchanger's coolant petcock.
5. Run the engine at idle and slowly pour clean, premixed coolant into the manifold.
6. Open the air-bleed petcock on the heat exchanger; close it when a steady flow of coolant appears.
7. Fill the manifold to the filler neck and install the manifold pressure cap.
8. Fill the coolant recovery tank to halfway between LOW and MAX and replace the cap.
9. Run the engine, check for leaks, stop and allow to cool; add coolant to the recovery tank if needed.

Source: Westerbeke operator's 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.

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