EGR Cooler

This procedure covers the removal and replacement of the EGR cooler on the 5.9L Cummins diesel engine, including exhaust system disconnection and coolant system service.

Warnings

Tools required

Parts

• EGR cooler assembly × 1 — Use OEM specification
• EGR cooler gaskets × 1 — Included with OEM cooler kit
• Exhaust flange gaskets × 2 — Use OEM specification
• Coolant hose clamps × 2 — As needed for damaged clamps
• EGR valve gasket × 1 — Use OEM specification

Fluids

• Ethylene glycol 50/50 (green conventional early, HOAT later) — 4 qt

Preparation

1. Ensure engine is completely cold to the touch (minimum 2 hours after operation)
2. Park vehicle on level surface and engage parking brake
3. Disconnect both battery terminals, negative first
4. Raise front of vehicle and secure on jack stands if additional clearance is needed
5. Place coolant drain pan under lower radiator hose connection
6. Apply penetrating oil to all exhaust flange bolts and manifold connections, allow 15-30 minutes to penetrate

Procedure

1. 1

   Drain cooling system
   Open radiator drain petcock or remove lower radiator hose to drain coolant into collection pan. Drain until coolant level is below EGR cooler connections (a significant portion of the ~5-6 gallon system will drain). Remove coolant reservoir cap to improve drainage flow.
2. 2

   Remove intake air components
   Remove intake air tube from turbocharger inlet to air filter housing. Disconnect any sensors or vacuum lines attached to intake tubing. Remove air filter housing if additional access is required. Set components aside in clean area.
3. 3

   Disconnect EGR valve
   Note: Most 1994-2007 5.9L Cummins engines were NOT equipped with a factory EGR system. Verify this specific vehicle actually has an EGR cooler before proceeding. If equipped (late-emissions models only), locate EGR valve, disconnect its electrical connector, remove mounting bolts securing it to the manifold, disconnect from EGR cooler outlet, and remove and discard the gasket.
4. 4

   Disconnect coolant lines from EGR cooler
   Using hose clamp pliers or screwdriver, loosen clamps on coolant inlet and outlet hoses at EGR cooler. Have shop towels ready to catch residual coolant. Carefully twist and pull hoses off EGR cooler connections. Inspect hoses for damage or deterioration.
   ⚠Residual coolant will drain from hoses and cooler. Position drain pan to catch spillage.
5. 5

   Remove upstream O2 sensor
   This step does not apply to the 5.9L Cummins diesel. The engine does not use an oxygen (O2) sensor in the exhaust. Skip this step and proceed to disconnecting the exhaust connections.
   Torque spec

   O2 Sensor45 Nm (33 lb-ft)
6. 6

   Disconnect exhaust inlet connection
   Remove exhaust flange bolts connecting EGR cooler to exhaust manifold or turbocharger outlet pipe. Separate flange and remove gasket. If bolts are severely corroded, use heat or additional penetrating oil as needed. Inspect studs for damage.
   ⚠Exhaust studs may break during removal on high-mileage vehicles. Have replacement studs available if needed.
   Torque spec

   Exhaust Flange Bolt45 Nm (33 lb-ft)
7. 7

   Disconnect exhaust outlet connection
   Remove exhaust flange bolts connecting EGR cooler outlet to downstream exhaust pipe. Separate flange and remove gasket. Support exhaust pipe to prevent strain on remaining connections.
8. 8

   Remove EGR cooler support brackets
   Remove any support brackets, hangers, or heat shields securing EGR cooler to engine block or frame. Remove mounting bolts and hanger bolts as applicable. Note bracket positions and orientation for reinstallation.
   Torque spec

   Hanger Bolts20 Nm (15 lb-ft)

   Heat Shield Bolts10 Nm (7 lb-ft)
9. 9

   Remove EGR cooler assembly
   With all connections and supports removed, carefully maneuver EGR cooler assembly out of engine bay. Assembly may require rotation or angling to clear surrounding components. Inspect mounting surfaces for carbon buildup or damage.
10. 10

    Clean mounting surfaces
    Using wire brush and gasket scraper, thoroughly clean all mating surfaces on exhaust flanges, EGR valve mounting surface, and coolant connections. Remove all carbon deposits, old gasket material, and corrosion. Ensure surfaces are flat and smooth for proper sealing.
11. 11

    Install new EGR cooler
    Position new EGR cooler assembly into engine bay, reversing removal process. Align exhaust flanges and loosely install new gaskets. Install all support brackets and hangers finger-tight. Ensure coolant connections are accessible and properly oriented before final tightening.
12. 12

    Torque exhaust connections
    Apply anti-seize compound to exhaust flange bolt threads. Install and torque exhaust flange bolts in cross-pattern to specification. Start with inlet flange to manifold/turbo, then torque outlet flange to exhaust pipe. Verify gaskets remain properly seated.
    Torque spec

    Exhaust Flange Bolt45 Nm (33 lb-ft)
13. 13

    Secure support brackets and sensors
    Torque all mounting bolts, hanger bolts, and heat shield bolts to specification.
    Torque spec

    Hanger Bolts20 Nm (15 lb-ft)

    Heat Shield Bolts10 Nm (7 lb-ft)

    O2 Sensor45 Nm (33 lb-ft)
14. 14

    Reconnect EGR valve and coolant lines
    Install new EGR valve gasket and mount EGR valve to intake manifold, torque mounting bolts to specification. Reconnect EGR valve electrical connector. Install coolant hoses onto EGR cooler connections and secure with new clamps, positioned away from previous clamp locations.
15. 15

    Refill and bleed cooling system
    Close radiator drain petcock or reinstall lower radiator hose. Add coolant mixture through radiator fill neck or reservoir until system is full. Start engine and run at idle with heater on maximum. Monitor coolant level and add as air purges from system. Check for leaks at all EGR cooler connections. When engine reaches operating temperature, verify proper coolant circulation and recheck level after engine cools.

Reassembly

1. Reinstall intake air components and verify all clamps are secure
2. Reconnect battery terminals, positive first then negative
3. Remove jack stands and lower vehicle if raised
4. Dispose of old coolant according to local environmental regulations

Verification

• Start engine and verify no coolant leaks at EGR cooler connections while cold and after reaching operating temperature
• Check for exhaust leaks at all flange connections using visual inspection and listening for hissing sounds
• Verify EGR system operation using scan tool to monitor EGR valve position and operation
• Monitor coolant level over next several days and top off as needed after complete air purge
• Inspect for white smoke from exhaust (indicates coolant contamination) during initial operation
• Verify no unusual exhaust odors in cabin with heater operating (indicates exhaust-to-coolant leak)

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