Detroit Diesel — Draining and Flushing the Cooling System
Maintenance
From a Detroit Diesel service manual — check it applies to your exact model before use.
Before you start
- HOT COOLANT: never remove the cooling system pressure cap while the engine is at operating temperature.
- Do not apply more than 140 kPa (20 psi) air pressure when flushing.
Procedure
- Open the cap on the surge tank slowly to allow excess pressure to escape.
- Open the water regulating valve for the heating system.
- Place a receptacle under the coolant drain plug and open the drain plug on the radiator bottom.
- Attach a flushing gun nozzle to the radiator outlet and run water in until full.
- Apply no more than 140 kPa (20 psi) air pressure intermittently to dislodge sediment.
- Drain and flush the radiator until clean water flows; remove the flushing gun.
- Install the coolant drain plug; tighten to 30 N·m (22 lb·ft).
- Add coolant in the specified concentration up to the maximum fill level on the surge tank.
- Start the engine and run about one minute at varying speeds to release air pockets.
- Check hoses at radiator, coolant pump, and surge tank for leaks; check coolant level.
- Shut down the engine and close and tighten the cap on the surge tank.
Tools required
- Flushing gun Amazon
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- Coolant drain plug 30 N·m (22 lb·ft)
- Maximum flushing air pressure 140 kPa (20 psi)
- Engine coolant capacity 30.0 L (31.7 qts)
Source: Detroit Diesel 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.