MBE 900 – Section 15.9 Excessive Exhaust Smoke (Black or Gray)

Section 15.9
Excessive Exhaust Smoke (Black or Gray)

There are many causes for excessive black or gray exhaust smoke. These probable causes are:‪

• Restricted Air Cleaner Element
• Restricted or Cracked Charge Air Cooler
• Faulty Air Intake Manifold Gasket
• Faulty Exhaust Manifold Gasket
• Aerated Fuel
• Faulty Fuel Nozzle
• Defective Turbocharger
• Improper Grade of Fuel
• Faulty EGR valve
• Incorrectly Adjusted Exhaust Brake
• Faulty Exhaust Brake Valve
• Faulty Exhaust Brake Cylinder
• Faulty Constant Throttle Valve
• Incorrect Valve Clearance
• Low Compression

Section 15.9.1
Troubleshooting Procedure for Restricted Air Cleaner Element

To determine if a restrictive air cleaner element is causing excessive black or gray smoke, perform the following:‪

1. Remove the air filter element from the air cleaner container; refer to OEM guidelines.
2. Visually inspect the air cleaner element for damage or clogging.
   1. If no damage or clogging is found, check the charge air cooler; refer to "15.9.3 Troubleshooting Procedure for a Restricted or Cracked Charge Air Cooler" .
   2. If damage or clogging is found, refer to "15.9.2 Air Filter Element Replacement" .

Section 15.9.2
Air Filter Element Replacement

Perform the following to replace the air filter element:‪

1. Remove and replace the damaged or clogged air filter element; refer to OEM guidelines.
2. Verify that replacing the air filter element eliminated the excessive exhaust smoke; refer to "15.9.2.1 Test the Engine with Replaced Air Filter Element" .

Section 15.9.2.1
Test the Engine with Replaced Air Filter Element

Perform the following to determine if the new filter element resolved excessive exhaust smoke:‪

PERSONAL INJURY ‪
To avoid injury before starting and running the engine, ensure the vehicle is parked on a level surface, parking brake is set, and the wheels are blocked. ‪

1. Start and run the engine.
2. Run the engine at idle with a no-load condition for approximately five minutes, allowing the engine coolant to reach normal operating range, approximately 88-96°C (190-205°F).
3. Visually inspect exhaust for excessive smoke.
   1. If the engine exhaust emission appears normal, no further troubleshooting is required. Shut down the engine.
   2. If the engine exhaust emission is excessively black or gray, shut down the engine. Check the charge air cooler; refer to "15.9.3 Troubleshooting Procedure for a Restricted or Cracked Charge Air Cooler" .

Section 15.9.3
Troubleshooting Procedure for a Restricted or Cracked Charge Air Cooler

To determine if a charge air cooler is causing excessive exhaust smoke, perform the following:‪

NOTICE:
To avoid engine damage, follow the installation instructions provided with the air-to-air charge air cooler test kit.‪

1. Visually inspect the core, tanks, and welds for cracks and holes. If charge air cooler fails visual inspection replace the charge air cooler. Refer to "15.9.4 Charge Air Cooler Replacement" .
2. Pressure test the charge air cooler;refer to "15.9.3.1 Pressure Testing the Charge Air Cooler" .
3. Evaluate the results from pressure testing the charge air cooler.
   1. If the pressure drop is 34 kPa (5 psi) or less in 15 seconds the cooler is good. Check for faulty air intake manifold. Refer to "15.9.5 Troubleshooting Procedure for a Faulty Air Intake Manifold Gasket" .
   2. If the pressure drop is greater than 34 kPa (5 psi) in 15 seconds, replace the charge air cooler. Refer to "15.9.4 Charge Air Cooler Replacement" .

Section 15.9.3.1
Pressure Testing the Charge Air Cooler

Perform the following to pressure test the charge air cooler:‪

1. Use the charge air cooler tester (J-41473) to test cooler for leaks. See Figure for component parts.
   

   1. Gauge Coupler‪	6. Gauge‪
   2. Bleed-off Coupler‪	7. Pressure Relief Valve‪
   3. Bleed Valve‪	8. Air Regulator Valve‪
   4. Safety Straps‪	9. Air Shutoff Valve‪
   5. Quick Disconnect‪	10. Quick Disconnect Fitting‪

   Figure 1. Charge Air Cooler Tester J-41473

2. Disconnect the air inlet and outlet piping connecting the charge air cooler to the engine.
3. Install the charge air cooler test gauge coupler into the inlet hose (hot side) of the charge air cooler coming from the turbocharger compressor. Secure hose and coupler with clamp removed and torque the clamp to 5.6-6.78 N·m (50-60 lb·in.). See Figure .
   

   1. Gauge/Regulator Assembly‪	6. Bleed-off Coupler‪
   2. Quick Disconnect Fitting‪	7. Charge Air Cooler Hose (Cold Side)‪
   3. Gauge Coupler‪	8. Clamp‪
   4. Charge Air Cooler Hose (Hot Side)‪	9. Charge Air Cooler‪
   5. Safety Strap‪

   Figure 2. Charge Air Cooler and Tester J-41473

4. Attach the gauge/regulator assembly to the quick disconnect fitting on the gauge coupler.
5. Use the clamp removed to attach the bleed-off coupler to the outlet hose (cold side) of the charge air cooler. Torque the clamp to 5.6-6.78 N·m (50-60 lb·in.).
6. Connect the safety straps on the couplers to any convenient screw on the radiator mounting bracket.

   PRESSURIZED AIR AND FLYING PARTICLES ‪
   To avoid injury to eye or face, wear a face shield or goggles when conducting a pressure test.‪

7. Attach an air pressure line, with filtered air, to the air shutoff valve and gradually pressurize the charge air cooler to a pressure of 205 kPa (30 psi). If necessary, perform the following steps to adjust the air regulator until the gauge reads 205 kPa (30 psi):
   1. Pull regulator knob outward to unlock.
   2. Turn knob to adjust pressure to 205 kPa (30 psi).
   3. Push the regulator knob back into locked position.
8. Close the air shutoff valve and monitor the gauge with a stop watch for 15 seconds. Note any decrease in air pressure.
9. Repeat test at least three times to verify results.
   1. In pressure drop is 34 kPa (5 psi) or less in 15 seconds the cooler is good.
   2. If the pressure drop is greater than 34 kPa (5 psi) in 15 seconds, replace the charge air cooler. Refer to "15.9.4 Charge Air Cooler Replacement" .
10. Slowly release pressure with the charge air cooler by opening the valve in the bleed-off coupler.
11. Remove all charge air cooler tester pieces and reconnect charge air cooler piping to the engine.
12. Reconnect air inlet and outlet piping to engine. Torque hose clamps to 5.6 - 6.78 N·m (50 - 60 lb·in.).

Section 15.9.4
Charge Air Cooler Replacement

Perform the following steps to replace the charge air cooler:‪

1. Replace the charge air cooler; refer to OEM guidelines.
2. Verify that the replacement of the charge air cooler eliminated the excessive exhaust smoke; refer to "15.9.5.1 Test the Engine with a Replaced Charge Air Cooler or Air Intake Manifold Gasket Replacement" .

Section 15.9.5
Troubleshooting Procedure for a Faulty Air Intake Manifold Gasket

Perform the following steps to troubleshoot the air intake manifold:‪

1. Remove the air intake manifold; refer to "6.2.1 Intake Manifold Removal" .
2. Inspect the air intake manifold and gaskets.
3. Install the air intake manifold with new gaskets; refer to "6.2.2 Intake Manifold Installation" .
4. Verify repair of the air intake manifold; refer to "15.9.5.1 Test the Engine with a Replaced Charge Air Cooler or Air Intake Manifold Gasket Replacement" .

Section 15.9.5.1
Test the Engine with a Replaced Charge Air Cooler or Air Intake Manifold Gasket Replacement

To determine if the replaced charge air cooler or air intake manifold gasket resolved the excessive exhaust smoke condition, perform the following:‪

PERSONAL INJURY ‪
To avoid injury before starting and running the engine, ensure the vehicle is parked on a level surface, parking brake is set, and the wheels are blocked. ‪

1. Start and run the engine.
2. Run the engine at idle with a no-load condition for approximately five minutes, allowing the engine coolant to reach normal operating range, approximately 88-96°C (190-205°F).
3. Visually inspect exhaust for excessive black or gray smoke.
   1. If the engine exhaust emission appears normal, no further troubleshooting is required. Shut down the engine.
   2. If the engine exhaust emission is excessively black or gray, shut down the engine. Check for a faulty exhaust system; refer to "15.9.6 Troubleshooting Procedure for a Faulty Exhaust System" .

Section 15.9.6
Troubleshooting Procedure for a Faulty Exhaust System

To determine if a faulty exhaust system is causing excessive black or gray exhaust smoke, perform the following:‪

1. Drill an 11/32 in. hole in the exhaust pipe, 125 - 305 mm (5 - 12 in.) from the turbocharger exhaust outlet.

   Note: The tapped hole must be in a comparatively straight section of the turbocharger exhaust outlet.

2. Tap the hole to accommodate a 1/8 in. pipe plug.
3. Connect a manometer calibrated to read pressure in kPa or inches of Hg to the tapped hole.

   PERSONAL INJURY ‪
   To avoid injury before starting and running the engine, ensure the vehicle is parked on a level surface, parking brake is set, and the wheels are blocked. ‪

4. Start and run the engine.
5. Run the engine at idle with a no-load condition for approximately five minutes, allowing the engine coolant to reach normal operating range, approximately 88-96°C (190-205°F).
6. Run the engine speed to full load.
   1. If the exhaust back pressure at full load is less than 12 kPa (3.5 in. Hg), check the fuel injectors and nozzles; refer to "15.9.10 Troubleshooting Procedure for a Faulty Fuel Nozzle" . Shut down the engine.
   2. If the exhaust back pressure at full load is 12 kPa (3.5 in. Hg) or greater, refer to "15.9.7 Engine Exhaust System Resolution" . Shut down the engine.

Section 15.9.7
Engine Exhaust System Resolution

Perform the following steps to resolve the engine exhaust system concern:‪

1. Visually inspect the engine exhaust system: refer to OEM guidelines.
2. Repair and replace defective exhaust system components; refer to OEM guidelines
3. Verify exhaust system resolutionrefer to "15.9.7.1 Test the Engine with Replaced Exhaust System" .

Section 15.9.7.1
Test the Engine with Replaced Exhaust System

Perform the following steps to determine if replaced engine exhaust manifold has resolved the excessive black or gray exhaust smoke condition:‪

PERSONAL INJURY ‪
To avoid injury before starting and running the engine, ensure the vehicle is parked on a level surface, parking brake is set, and the wheels are blocked. ‪

1. Start and run the engine.
2. Run the engine at idle with a no-load condition for approximately five minutes, allowing the engine coolant to reach normal operating range, approximately 88-96°C (190-205°F).
3. Visually inspect exhaust for excessive smoke.
   1. If the engine exhaust emission appears normal, no further troubleshooting is required. Shut down the engine.
   2. If the engine exhaust emission is excessively black or gray, shut down the engine. Check the fuel nozzles; refer to "15.9.8 Troubleshooting Procedure for Aerated Fuel" .

Section 15.9.8
Troubleshooting Procedure for Aerated Fuel

To determine if aerated fuel is causing excessive exhaust smoke, perform the following steps:‪

1. Disconnect the fuel line return hose from the fitting located at the fuel tank; refer to OEM guidelines.
2. Place the opened end of the fuel line into a suitable container.

   PERSONAL INJURY ‪
   To avoid injury before starting and running the engine, ensure the vehicle is parked on a level surface, parking brake is set, and the wheels are blocked. ‪

3. Start the engine.
4. Run the engine at 1000 rpm.
5. Visually check to see if air bubbles are rising to the surface of the fuel within the container.
   1. If air bubbles are present, repair is necessary; refer to "15.9.9 Aerated Fuel Resolution" .
   2. If air bubbles are not present, check for a low compression. Shut down the engine; refer to "15.9.10 Troubleshooting Procedure for a Faulty Fuel Nozzle" .

Section 15.9.9
Aerated Fuel Resolution

Perform the following steps for aerated fuel resolution:‪

1. Shut down the engine.
2. Tighten all fuel line connections between fuel tank and fuel pump; refer to OEM guidelines.
3. Visually inspect all fuel lines between fuel tank and fuel pump for leaks.
4. Replace damaged components as required.
5. Verify aerated fuel resolution corrected the excessive exhaust smoke condition; refer to "15.9.9.1 Test Engine with Aerated Fuel Resolution" .

Section 15.9.9.1
Test Engine with Aerated Fuel Resolution

To determine if aerated fuel resolution resolved the excessive exhaust smoke concern, perform the following steps:‪

PERSONAL INJURY ‪
To avoid injury before starting and running the engine, ensure the vehicle is parked on a level surface, parking brake is set, and the wheels are blocked. ‪

1. Attempt to start and run the engine, if the engine starts and runs with no exhaust smoke, no further troubleshooting is required. Shut down the engine.
2. If the engine still has excessive exhaust smoke, check for faulty fuel nozzle; refer to "15.9.20 Troubleshooting Procedure for Low Compression" .

Section 15.9.10
Troubleshooting Procedure for a Faulty Fuel Nozzle

To troubleshoot the fuel nozzle, refer to "15.3 Fuel Injection Troubleshooting" on Fuel Injection Troubleshooting. After completing fuel injection troubleshooting, verify that repairs made corrected the excessive exhaust smoke. Refer to "15.9.10.1 Test the Engine with Replaced Fuel Nozzle" .‪

Section 15.9.10.1
Test the Engine with Replaced Fuel Nozzle

Perform the following steps to determine if replaced fuel nozzle has resolved the excessive black or gray exhaust smoke condition:‪

PERSONAL INJURY ‪
To avoid injury before starting and running the engine, ensure the vehicle is parked on a level surface, parking brake is set, and the wheels are blocked. ‪

1. Start and run the engine.
2. Run the engine at idle with a no-load condition for approximately five minutes, allowing the engine coolant to reach normal operating range, approximately 88-96°C (190-205°F).
3. Visually inspect exhaust for excessive smoke.
   1. If the engine exhaust emission appears normal, no further troubleshooting is required. Shut down the engine.
   2. If the engine exhaust emission is excessively black or gray, shut down the engine. Check the turbocharger; refer to "15.9.11 Troubleshooting Procedure for a Defective Turbocharger" .

Section 15.9.11
Troubleshooting Procedure for a Defective Turbocharger

To determine if a defective turbocharge is causing excessive exhaust smoke, perform the following:‪

1. Remove the turbocharger oil drain outlet line connected to the crankcase and place the drain line into a suitable container; refer to "6.4.2 Turbocharger Removal" .
2. Rotate turbine wheel to check for free movement. If wheel does not move freely, replace turbocharger; refer to "6.4.3 Turbocharger Installation" .
3. Verify that replacing the turbocharger corrected the excessive smoke problem; refer to "15.9.11.1 Test Engine with a Replaced Turbocharger" .
4. Perform a crankcase pressure test; refer to "15.4.10.1 Crankcase Pressure Test" .
   1. If the engine crankcase pressure is less than 0.62 kPa (2.5 in. H₂ O), shut down the engine and replace the turbocharger; refer to "6.4.3 Turbocharger Installation" . Verify replaced turbocharger corrected the excessive smoke problem; refer to "15.9.11.1 Test Engine with a Replaced Turbocharger" .
   2. If the engine crankcase pressure is greater than 0.62 kPa (2.5 in. H₂ O), shut down the engine. Connect the oil drain outlet line to the turbocharger and call the Detroit Diesel Customer Support Center at 313-592-5800.

Section 15.9.11.1
Test Engine with a Replaced Turbocharger

Perform the following steps to determine if a replaced turbocharger has resolved the excessive exhaust smoke condition:‪

PERSONAL INJURY ‪
To avoid injury before starting and running the engine, ensure the vehicle is parked on a level surface, parking brake is set, and the wheels are blocked. ‪

1. Start the engine.
2. Run the engine speed to full load.
3. Visually inspect the exhaust for excessive black or gray smoke.
   1. If the engine exhaust emission appears normal, no further troubleshooting is required. Shut down the engine.
   2. If the engine exhaust emission is excessive, shut down the engine, check for improper grade of fuel. Refer to "15.9.12 Troubleshooting Procedure for Improper Grade of Fuel" .

Section 15.9.12
Troubleshooting Procedure for Improper Grade of Fuel

To determine if an improper grade of fuel is causing excessive black or gray smoke, perform the following:‪

1. Acquire a fuel sample from the vehicle fuel tank(s).
2. Submit fuel sample for an ASTM test analysis.
   1. If the fuel meets specifications, check for a faulty EGR valve; refer to "15.9.14 Troubleshooting Procedure for a Faulty EGR  Valve" .
   2. If the fuel did not meet specifications, resolve improper grade of fuel; refer to "15.9.13 Improper Grade of Fuel Resolution" and DDC publication Lubricating Oil, Fuel, and Filters (7SE270).

Section 15.9.13
Improper Grade of Fuel Resolution

Perform the following steps to resolve the improper grade of fuel:‪

1. Drain the fuel tanks, refer to OEM guidelines, and dispose of fuel properly.
2. Refill the fuel tanks with new fuel having a cetane number greater than 45 and cetane index greater than 40.
3. Verify fuel resolution eliminated the excessive exhaust smoke condition; refer to "15.9.13.1 Test the Engine with New Fuel" .

Section 15.9.13.1
Test the Engine with New Fuel

Perform the following steps to determine if the fuel refill resolved the excessive exhaust smoke condition:‪

PERSONAL INJURY ‪
To avoid injury before starting and running the engine, ensure the vehicle is parked on a level surface, parking brake is set, and the wheels are blocked. ‪

1. Start and run the engine.
2. Run the engine at idle under no-load conditions for approximately five minutes, allowing the engine coolant to reach normal operating range, approximately 88-96°C (190-205°F).
3. Visually inspect exhaust for excessive smoke.
   1. If the engine smoke emission appears normal, no further troubleshooting is required. Shut down the engine.
   2. If the engine exhaust smoke is excessively black or gray, shut down the engine. Check the EGR valve; refer to "15.9.14 Troubleshooting Procedure for a Faulty EGR  Valve" .

Section 15.9.14
Troubleshooting Procedure for a Faulty EGR  Valve

To determine if a faulty EGR valve is causing excessive black or gray smoke, perform the following:‪

1. Remove the EGR valve; refer to "10.6.1 EGR Rotary Valve Removal" .
2. Inspect the EGR valve flap for freedom of movement.
   1. If freedom of movement is restricted remove soot and clean deposits as required.
   2. If movement of valve is still not free, replace the EGR valve. Refer to "10.6.2 EGR Rotary Valve Installation" . Verify the replacement of the EGR valve corrected the excessive exhaust smoke concern; refer to "15.9.14.1 Test the Engine with Replaced EGR Valve"
3. Perform a PV2 activation test to verify flap valve functionality. Call Detroit Diesel Customer Support Center at 313-592-5800 for instructions.

Section 15.9.14.1
Test the Engine with Replaced EGR Valve

Perform the following steps to determine if the replaced EGR valve resolved the excessive exhaust smoke condition:‪

PERSONAL INJURY ‪
To avoid injury before starting and running the engine, ensure the vehicle is parked on a level surface, parking brake is set, and the wheels are blocked. ‪

1. Start and run the engine.
2. Run the engine at idle under no-load conditions for approximately five minutes, allowing the engine coolant to reach normal operating range, approximately 88-96°C (190-205°F).
3. Visually inspect exhaust for excessive smoke.
   1. If the engine smoke emission appears normal, no further troubleshooting is required. Shut down the engine.
   2. If the engine exhaust smoke is excessively black or gray, shut down the engine. Check the exhaust brake valve; refer to "15.9.16 Troubleshooting Procedure for a Faulty Exhaust Brake Valve" .

Section 15.9.15
Troubleshooting Procedure for a Incorrectly Adjusted Exhaust Brake Valve

To determine if a misadjusted exhaust brake valve is causing excessive black or gray smoke, perform the following:‪

1. Readjust the exhaust brake valve; refer to "7.2.3 Exhaust Brake Assembly, 6-Cylinder Engine" for a 6-cylinder engine or refer to "7.2.5 Exhaust Brake Assembly, 4-Cylinder Engine" for a 4-cylinder engine.
2. Verify the adjustment on the exhaust brake valve; refer to "15.9.15.1 Test Engine After Adjusting the Exhaust Brake Valve"

Section 15.9.15.1
Test Engine After Adjusting the Exhaust Brake Valve

Perform the following steps to determine if the exhaust brake adjustment resolved the excessive exhaust smoke condition:‪

PERSONAL INJURY ‪
To avoid injury before starting and running the engine, ensure the vehicle is parked on a level surface, parking brake is set, and the wheels are blocked. ‪

1. Start and run the engine.
2. Run the engine at idle under no-load conditions for approximately five minutes, allowing the engine coolant to reach normal operating range, approximately 88-96°C (190-205°F).
3. Visually inspect exhaust for excessive smoke.
   1. If the engine smoke emission appears normal, no further troubleshooting is required. Shut down the engine.
   2. If the engine exhaust smoke is excessively black or gray, shut down the engine. Check the exhaust brake valve; refer to "15.9.16 Troubleshooting Procedure for a Faulty Exhaust Brake Valve" .

Section 15.9.16
Troubleshooting Procedure for a Faulty Exhaust Brake Valve

To determine if a faulty exhaust brake valve is causing excessive black or gray smoke, check exhaust brake valve for freedom of movement.‪

1. If movement is not free, replace exhaust brake valve; refer to "7.2 Exhaust Brake Assembly" . Verify replacement of the exhaust brake valve; refer to "15.9.16.1 Test Engine for Replaced Exhaust Brake Valve" .
2. If movement is free, check the exhaust brake cylinder; refer to "15.9.17 Troubleshooting Procedure for a Faulty Exhaust Brake Cylinder" .

Section 15.9.16.1
Test Engine for Replaced Exhaust Brake Valve

Perform the following steps to determine if the replaced exhaust brake valve resolved the excessive exhaust smoke condition:‪

PERSONAL INJURY ‪
To avoid injury before starting and running the engine, ensure the vehicle is parked on a level surface, parking brake is set, and the wheels are blocked. ‪

1. Start and run the engine.
2. Run the engine at idle under no-load conditions for approximately five minutes, allowing the engine coolant to reach normal operating range, approximately 88-96°C (190-205°F).
3. Visually inspect exhaust for excessive smoke.
   1. If the engine smoke emission appears normal, no further troubleshooting is required. Shut down the engine.
   2. If the engine exhaust smoke is excessively black or gray, shut down the engine. Check the exhaust brake cylinder; refer to "15.9.17 Troubleshooting Procedure for a Faulty Exhaust Brake Cylinder" .

Section 15.9.17
Troubleshooting Procedure for a Faulty Exhaust Brake Cylinder

To determine if a faulty exhaust brake cylinder is causing excessive black or gray smoke, check exhaust brake cylinder for full movement of travel by applying regulated air to cylinder.‪

1. If movement of travel is not full, replace the exhaust brake cylinder; refer to "7.2.1 Exhaust Brake Assembly Removal" . Verify replacement of exhaust brake cylinder corrected the excessive exhaust smoke concern; refer to "15.9.17.1 Test Engine for Replaced Engine Brake Cylinder" .
2. If full movement of travel is obtained, refer to "15.9.18 Troubleshooting Procedure for a Faulty Constant Throttle Valve" .

Section 15.9.17.1
Test Engine for Replaced Engine Brake Cylinder

Perform the following steps to determine if the replaced engine brake cylinder resolved the excessive exhaust smoke condition:‪

PERSONAL INJURY ‪
To avoid injury before starting and running the engine, ensure the vehicle is parked on a level surface, parking brake is set, and the wheels are blocked. ‪

1. Start and run the engine.
2. Run the engine at idle under no-load conditions for approximately five minutes, allowing the engine coolant to reach normal operating range, approximately 88-96°C (190-205°F).
3. Visually inspect exhaust for excessive smoke.
   1. If the engine smoke emission appears normal, no further troubleshooting is required. Shut down the engine.
   2. If the engine exhaust smoke is excessively black or gray, shut down the engine. Check the constant throttle valve; refer to "15.9.18 Troubleshooting Procedure for a Faulty Constant Throttle Valve" .

Section 15.9.18
Troubleshooting Procedure for a Faulty Constant Throttle Valve

To determine if a faulty constant throttle valve is causing excessive black or gray smoke, measure the resistance between wire 52 in the 55-pin connector and vehicle ground.‪

1. If the resistance is greater than 30 kΩ, replace the constant throttle valve; refer to "3.8.9 CTV Control Valve Removal" . Verify the replacement of the constant throttle valve; refer to "15.9.18.1 Test Engine for Replaced Constant Throttle Valve" .
2. If the resistance is less than 30 kΩ, refer to "15.9.19 Troubleshooting Procedure for Improper Valve Clearance, Worn or Damaged Camshaft Lobes and Rollers" .

Section 15.9.18.1
Test Engine for Replaced Constant Throttle Valve

Perform the following steps to determine if the replaced constant throttle valve resolved the excessive exhaust smoke condition:‪

PERSONAL INJURY ‪
To avoid injury before starting and running the engine, ensure the vehicle is parked on a level surface, parking brake is set, and the wheels are blocked. ‪

1. Start and run the engine.
2. Run the engine at idle under no-load conditions for approximately five minutes, allowing the engine coolant to reach normal operating range, approximately 88-96°C (190-205°F).
3. Visually inspect exhaust for excessive smoke.
   1. If the engine smoke emission appears normal, no further troubleshooting is required. Shut down the engine.
   2. If the engine exhaust smoke is excessively black or gray, shut down the engine. Refer to "15.9.19 Troubleshooting Procedure for Improper Valve Clearance, Worn or Damaged Camshaft Lobes and Rollers" .

Section 15.9.19
Troubleshooting Procedure for Improper Valve Clearance, Worn or Damaged Camshaft Lobes and Rollers

To determine if an improper valve clearance, worn or damaged camshaft lobes or rollers are causing excessive exhaust smoke, perform the following:‪

1. Check for improper valve clearance, and worn or damaged camshaft lobes and rollers. Repair as required. Refer to "1.17.2 Checking Valve Lash" and section "1.20.1.1 Camshaft Inspection" .
2. Verify valve clearance, worn or damaged camshaft lobes and rollers repair corrected the excessive exhaust smoke concern; refer to "15.9.19.1 Test Engine with Corrected Valve Clearance, Worn or Damaged Camshaft Lobes and Rollers" .

Section 15.9.19.1
Test Engine with Corrected Valve Clearance, Worn or Damaged Camshaft Lobes and Rollers

Perform the following steps to determine if the valve clearance, worn or damaged camshaft lobes and rollers repair has resolved excessive exhaust smoke condition:‪

PERSONAL INJURY ‪
To avoid injury before starting and running the engine, ensure the vehicle is parked on a level surface, parking brake is set, and the wheels are blocked. ‪

1. Start and run the engine.
2. Run the engine at idle with a no-load condition for approximately five minutes, allowing the engine coolant to reach normal operating range.
3. Visually inspect exhaust for excessive exhaust smoke.
   1. If the engine exhaust smoke emission appears normal, no further troubleshooting is required. Shut down the engine.
   2. If the engine exhaust smoke emission is excessive, shut down the engine. Check for low compression; refer to "15.9.20 Troubleshooting Procedure for Low Compression" .

Section 15.9.20
Troubleshooting Procedure for Low Compression

To determine if low compression is causing excessive exhaust smoke, perform the following steps:‪

1. Perform a cylinder compression test; refer to "1.2.2.2 Compression Testing" .
2. Compare cylinder compression test results to specifications as listed in Table "Compression Testing Specifications" .

   Description‪	Pressure in kPa (psi)‪
   Compression Pressure at Starter Speed‪	2800 (406)‪
   Permissible Difference between Individual Cylinders‪	400 (58)‪

   Table 20. Compression Testing Specifications
   1. If cylinder pressure is below specifications, refer to "15.9.21 Low Compression Repair" .
   2. If cylinder pressure is within specifications, call Detroit Diesel Customer Support Center at 313-592-5800.

Section 15.9.21
Low Compression Repair

Perform the following steps for low compression repair.‪

1. Remove cylinder head; refer to "1.2.1 Cylinder Head Removal" .
2. Inspect the cylinder head for worn or damaged valves; refer to "1.17 Valves" .
3. Replace damaged valves; refer to "1.17.5 Valve Removal" .
4. Inspect the cylinder kit components for worn or damaged liners, pistons; or piston rings.
5. Verify repairs made to cylinder head valve(s) or cylinder kit components have corrected the excessive exhaust smoke concern; refer to "15.9.21.1 Test Engine with Repaired Cylinder Head Valve(s), and Cylinder Kit" .

Section 15.9.21.1
Test Engine with Repaired Cylinder Head Valve(s), and Cylinder Kit

To determine if the cylinder head valve and cylinder kit repair resolved excessive exhaust smoke, perform the following steps:‪

PERSONAL INJURY ‪
To avoid injury before starting and running the engine, ensure the vehicle is parked on a level surface, parking brake is set, and the wheels are blocked. ‪

1. Attempt to start and run the engine, if the engine starts and runs without excessive exhaust smoke, no further troubleshooting is required. Shut down the engine.
2. If the engine continues to have excessive exhaust smoke, call the Detroit Diesel Customer Support Center at 313-592-5800.