68715 Mercruiser GASKET,EXHAUST MANIFOLD TO HEAD

Table 1
J1939 Code and Description CDL Code and Description Comments
173–16
Engine Exhaust Gas Temperature: High - moderates severity (2) E194 (2)
High Exhaust Temperature The exhaust gas temperature is higher than expected for the engine operating conditions.
173-31
Engine Exhaust Gas Temperature E21(1)
Engine Exhaust Gas Temperature Engine protection derate due to high exhaust temperatures. Note: Certain operating conditions may cause the calculated exhaust temperature to increase to a level that may damage engine components. If a high exhaust temperature occurs, the ECM derates the engine to reduce the calculated exhaust temperature. The engine is derated only to a level that allows the calculated exhaust temperature to return to an acceptable level.High intake manifold air temperature, high altitude operation, and high engine loads can cause the exhaust temperature to increase to a level that may damage the components of the exhaust system. When this occurs, the ECM derates the engine to reduce the exhaust temperature. This protects the components of the exhaust system from damage.Probable Causes
Inlet air temperature is high
Inlet air is restricted
Engine overload
Exhaust restriction
Heavy buildup of deposits in the cylinder or internal oil leaksRecommended Actions
Note: The procedures have been listed in order of probability. Complete the procedures in the order of the listed test steps.
Table 2
Troubleshooting Test Step Value Result
1. Check for High Inlet Air Temperature
Refer to Troubleshooting, "Inlet Air Temperature Is High".
A one degree increase in the inlet manifold temperature will increase the exhaust temperature by approximately three degrees.
Temperature
Result: The inlet air temperature is OK.
Proceed to the next step.
Result: The inlet air temperature is NOT OK.
Repair: Determine the cause of the high inlet air temperature and correct the problem.
If the problem is not resolved, proceed to the next step.
2. Check for Inlet Air Restriction
Refer to Troubleshooting, "Inlet Air Is Restricted".
Note: Inlet air restriction can cause uneven exhaust port temperatures. For example, the cylinders at the front half of the engine may have exhaust port temperatures that are 10 to 20 °C (18 to 36 °F) higher than the exhaust port temperatures that are for the cylinders at the rear half of the engine. If this condition occurs, measure the inlet air restriction for each turbocharger. Make repairs in order to equalize the inlet air restriction for each of the turbochargers.
Setting
Result: The inlet air is not restricted.
Proceed to the next step.
Result: The inlet air is restricted.
Repair: Determine the reason for high inlet air restriction and repair.
If the problem is not resolved, proceed to the next step.
3. Check for Engine Overload
When the load that is applied to the engine is too large, the engine will run in the lug condition. When the engine is running in the lug condition, engine rpm does not increase with an increase of fuel.
Load
Result: The engine is not being overloaded.
Proceed to the next step.
Result: The engine is being overloaded.
Repair: Reduce engine load to an acceptable limit.
If the problem is not resolved, proceed to the next step.
4. Check for Exhaust Restriction
A restriction of the exhaust can cause high cylinder temperatures.
A. Measure the exhaust restriction during engine operation with a load.
Restriction
Result: The exhaust restriction measures OK.
Proceed to the next step.
Result: The exhaust restriction measurement is NOT OK.
Repair: Determine the reason for high exhaust restriction and repair.
If the problem is not resolved, proceed to the next step.
5. Check for Heavy Buildup of Deposits in the Cylinder or Internal Oil Leaks
A. Use a borescope to inspect the cylinders. Look for the following conditions:
- Deposits on the valve seats
- Deposits on the valve faces
- Deposits on the cylinder walls that are above the upper limit of the piston stroke
- Signs of internal oil leaks
Deposits
Result: The cylinder check is NOT OK.
Repair: Determine the cause of the condition. Perform the necessary repairs.
If the procedure did not correct the issue, contact your Cat dealer Technical Communicator (TC). For further assistance, your TC can confer with the Dealer Solutions Network (DSN).