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Cummins ISX11.9 CM2250 – Service Manual t00-004   Troubleshooting Overview

Engine Noise Diagnostic Procedures – General Information

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NOTE: When diagnosing engine noise problems, make sure that noises caused by accessories, such as the air compressor and power takeoff, are not mistaken for engine noises. Remove the accessory drive belts to eliminate noise caused by these units. Noise will also travel to other metal parts not related to the problem. The use of a stethoscope can help locate an engine noise.

Engine noises heard at the crankshaft speed, engine rpm, are noises related to the crankshaft, rods, pistons, and piston pins. Noises heard at the camshaft speed, one-half of the engine rpm, are related to the valve train. A handheld digital tachometer can help to determine if the noise is related to components operating at the crankshaft or camshaft speed.

Engine noise can sometimes be isolated by performing a cylinder cutout test. Refer to the Electronic Service Tool Manual. If the volume of the noise decreases or the noise disappears, it is related to that particular engine cylinder.

There is not a definite rule or test that will positively determine the source of a noise complaint.

Engine driven components and accessories, such as gear-driven fan clutches, hydraulic pumps, belt-driven alternators, air-conditioning compressors, and turbochargers can contribute to engine noise. Use the following information as a guide to diagnosing engine noise.

Main Bearing Noise

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(Refer to Engine Noise Excessive – Main Bearing symptom tree)

The noise caused by a loose main bearing is a loud dull knock heard when the engine is pulling a load. If all main bearings are loose, a loud clatter will be heard. The knock is heard regularly every other revolution. The noise is the loudest when the engine is lugging or under heavy load. The knock is duller than a connecting rod noise. Low oil pressure can also accompany this condition.

If the bearing is not loose enough to produce a knock by itself, the bearing can knock if the oil is too thin, or if there is no oil at the bearing.

An irregular noise can indicate worn crankshaft thrust bearings.

An intermittent sharp knock indicates excessive crankshaft end clearance. Repeated clutch disengagements can cause a change in the noise.

Connecting Rod Bearing Noise

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(Refer to Engine Noise Excessive – Connecting Rod symptom tree)

Connecting rods with excessive clearance knock at all engine speeds, and under both idle and load conditions. When the bearings begin to become loose, the noise can be confused with piston slap or loose piston pins. The noise increases in volume with engine speed. Low oil pressure can also accompany this condition.

Piston Noise

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(Refer to Engine Noise Excessive – Piston symptom tree)

It is difficult to tell the difference between piston pin, connecting rod, and piston noise. A loose piston pin causes a loud double knock which is usually heard when the engine is idling. When the injector to this cylinder is cut out, a noticeable change will be heard in the sound of the knocking noise. However, on some engines the knock becomes more noticeable when the vehicle is operated on the road at steady speed condition.

Driveability – General Information

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Driveability is a term which in general describes vehicle performance on the road. Driveability problems for an engine can be caused by several different factors. Some of the factors are engine related and some are not.

Before troubleshooting, it is important to determine the exact complaint and whether the engine has a real driveability problem or if it simply does not meet driver expectations. The Driveability-Low Power Customer Complaint Form is a valuable list of questions that must be used to assist the service technician in determining what type of driveability problem the vehicle is experiencing. Complete the checklist before troubleshooting the problem. The form can be found at the end of this section. If an engine is performing to factory specifications but does not meet the customer’s expectations, it must be explained to the customer that nothing is wrong with the vehicle and why.

The troubleshooting symptom charts have been set up to divide driveability problems into two different symptoms: Engine Power Output Low and Engine Acceleration or Response Poor.

Low power is a term that is used in the field to describe many different performance problems. However, in this manual low power is defined as the inability of the engine to produce the power necessary to move the vehicle at a speed that can be reasonably expected under the given conditions of load, grade, wind, and so on. Low power is usually caused by the lack of fuel flow which can be caused by any of the following factors:

  • Lack of full travel of the throttle pedal
  • Failed boost sensor
  • Excessive fuel inlet, intake, exhaust, or drainline restriction
  • Loose fuel pump suction lines

Low power is not the inability of the vehicle to accelerate satisfactorily from a stop or the bottom of a grade. Refer to the symptom tree Engine Power Output Low for the proper procedures to locate and correct a low power problem. The chart starts off with basic items which can cause lower power. It then breaks off into application specific items that can cause lower power. All of the application specific trees end with a step called “Fuel or air delivery problem”. This step leads to an engine performance check which requires engine measurements. The last section of this chart is titled Performance Measurement. This leads the mechanic through the causes and corrections based on the outcome of the performance check.

Poor acceleration or response is described in this manual as the inability of the vehicle to accelerate satisfactorily from a stop or from the bottom of a grade. It can also be the lag in acceleration during an attempt to pass or overtake another vehicle at conditions less than rated speed and load. Poor acceleration or response is difficult to troubleshoot since it can be caused by factors such as:

  • Engine or pump related factors
  • Driver technique
  • Improper gearing
  • Improper engine application
  • Worn clutch or clutch linkage

Engine related poor acceleration or response can be caused by several different factors such as:

  • Failed boost sensor
  • Excessive drainline restriction
  • Throttle deadband

Refer to the Engine Acceleration or Response Poor symptom tree for the proper procedures to locate and correct a poor acceleration or response complaint. For additional information, see Troubleshooting Driveability Complaints, Bulletin 3387245.

Driveability/Low Power – Customer Complaint Form

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Customer Name/Company __________________________________________________________ Date ________________

  1. How did the problem occur? …. Suddenly ________ Gradually ________
  2. Does the vehicle also experience poor fuel economy? …. Yes ____ No ____
  3. At what hour/mileage did the problem begin? …. Hours ________ Miles ________ Since New ________
  1. After engine repair? …. Yes ____ No ____
  2. After equipment repair? …. Yes _____ No ____
  3. After change in equipment use? …. Yes ____ No ____
  4. After change in selectable programmable parameters? …. Yes ____ No ____
  5. If so, what was repaired and when? …………………………………………………………………………….

Answer questions 4 through 8 using selections (A through F) listed below. Circle the letter or letters that best describes the complaint.

  1. Compared to fleet
  2. Compared to competition
  3. Compared to previous engine
  4. Personal expectation
  5. Won’t pull on hill
  6. Won’t pull on flat
  1. A B C D E F Can the vehicle obtain the expected road speed? …. Yes ____ No ____ What is desired speed? …. rpm/mph ________ What is achieved speed? …. rpm/mph ________ GVW ________________
  2. A B C D Is the vehicle able to pull the load? …. Yes ____ No ____ When? In the hills ________ With a loaded trailer ________ On the flat ________ Other_______IF QUESTION 4 OR 5 WAS ANSWERED NO, FILL OUT THE DRIVEABILITY/LOW POWER/EXCESSIVE FUEL CONSUMPTION CHECKLIST AND GO TO THE LOW POWER SYMPTOM TREE.
  3. A B C D E F Is the vehicle slow to accelerate or respond? …. Yes ____ No ____ From a stop? …. Yes ____ No ____ After a shift? …. Yes ____ No ____ rpm ________ Before a shift? …. Yes ____ No ____ rpm ________ No shift? …. Yes ____ No ____ rpm ________
  4. A B C D Does the vehicle hesitate after periods of long deceleration or coasting? …. Yes ____ No ____ rpm _______IF QUESTION 6 OR 7 WAS ANSWERED YES, FILL OUT THE DRIVEABILITY/LOW POWER/EXCESSIVE FUEL CONSUMPTION CHECKLIST AND GO TO THE POOR ACCELERATION/RESPONSE SYMPTOM TREE.
  5. A B C D E F Additional Comments:

This Page Can Be Copied For Your Convenience.

Driveability/Low Power/Excessive Fuel Consumption – Checklist

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Vehicle/Equipment Specifications
Year/Type/Model:
Wheel Base:
Vehicle Configuration (ex. 6 X 4 – 2S):
Transmission Mfg:
Transmission Model:
Rear Axle Model:
Rear Axle Ratio:
Application:
On Highway:
Off Highway:
Genset:
Marine:
Typical GVW (kg [lbs]):
Trailer Type (Van, round smooth, etc.):
Height:
Width:
Gap between Tractor and Trailer:
Description of Vehicle aerodynamic aids:
General Engine Information
ESN:
CPL:
EPA Certification Year:
ECM Code:
Engine Model:
Engine Rating:
Rated Speed:
Date in Service:
Mpg (average if multiple units):
Engine Brake:
Yes
No
Throttle Type:
Variable Speed
Automotive
Tires
Steer:
Tire Mfg
Tire Model
Rev/Mile
Drive:
Tire Mfg
Tire Model
Rev/Mile
Trailer:
Tire Mfg
Tire Model
Rev/Mile
Fan Type:
Direct Drive
Viscous
Clutch
Est. HP
Auxiliary Devices
Power Steering:
Yes
No
Air Conditioner:
None
Standard
Bus
High Capacity
Alternator:
Amperes@Volts
Road Speeds
Maximum Cruise Control Speed:
Maximum Accelerator Vehicle Speed:
Shift Technique:
Progressive Shift
Governed Speed Shift
Electronic Features
Gear Down Protection – Heavy Load:
mph
Gear Down Protection – Light Load:
mph
Cruise Control Upper Droop:
mph
Cruise Control Lower Droop:
mph
Road Speed Governor Upper Droop:
mph
Road Speed Governor Lower Droop:
mph
Typical Routes
Route:
Interstate
Dump
Rural
Urban
Bus
Grades:
Level 1-2%
Short 1-5%
Long 1-5%
Additional Comments:
Recommended Literature:
Troubleshooting Driveability Complaints, Bulletin 3387137

Fuel Consumption – General Information

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The cause of excessive fuel consumption is hard to diagnose and correct because of the potential number of factors involved. Actual fuel consumption problems can be caused by any of the following factors:

  • Engine factors
  • Vehicle factors and specifications
  • Environmental factors
  • Driver technique and operating practices
  • Fuel system factors
  • Low power/driveability problems

Before troubleshooting, it is important to determine the exact complaint. Is the complaint based on whether the problem is real or perceived, or does not meet driver expectations? The Fuel Consumption – Customer Complaint Form (on the next page) is a valuable list of questions that can be used to assist the service technician in determining the cause of the problem. Complete the form before troubleshooting the complaint. The following are some of the factors that must be considered when troubleshooting fuel consumption complaints.

  1. Result of a Low Power/Driveability Problem: An operator will change his driving style to compensate for a low power/driveability problem. Some things the driver is likely to do are, (a) shift to a higher engine rpm or (b) run on the droop curve in a lower gear instead of upshifting to drive at part throttle conditions. These changes in driving style will increase the amount of fuel used.
  2. Driver Technique and Operating Practices: As a general rule, a 1 mph increase in road speed equals a 0.1 mpg increase in fuel consumption. This means that increasing road speed from 50 to 60 mph will result in a loss of fuel mileage of 1 mpg.
  3. Environmental and Seasonal Weather Changes: As a general rule, there can be as much as a 1 to 1.5 mpg difference in fuel consumption depending on the season and the weather conditions.
  4. Excessive Idling Time: Idling the engine can use from 0.5 to 1.5 gallons per hour depending on the engine idle speed.
  5. Truck Route and Terrain: East/west routes experience almost continual crosswinds and head winds. Less fuel can be used on north/south routes where parts of the trip are not only warmer, but see less wind resistance.
  6. Vehicle Aerodynamics: The largest single power requirement for a truce is the power needed to overcome air resistance. As a general rule, each 10 percent reduction in air resistance results in a 5 percent increase in mpg.
  7. Rolling Resistance: Rolling resistance is the second largest consumer of power on a truck. The type of tire and tread design have a sizeable effect on fuel economy and performance. Changing from a bias ply to a low profile radial tire can reduce rolling resistance by about 36 percent.

Additional vehicle factors, vehicle specifications, and axle alignment can also affect fuel consumption. For additional information on troubleshooting fuel consumption complaints, refer to Troubleshooting Excessive Fuel Consumption, Bulletin 3387245.

Fuel Consumption – Customer Complaint Form

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Customer Name/Company __________________________________________________________ Date ________________

Customer Contact _________________________________________________Customer Phone Number ________________

Describe the issue/complaint in detail, including current fuel economy being achieved:

______________________________________________________________________________________________________

______________________________________________________________________________________________________

Answer the following questions. Some questions require making an X next to the appropriate answer.

  1. What is the expected fuel mileage? _______________
  2. What is the average GVW? _______________
  3. What are the expectations based on?Original mileage ________ Other units in fleet ________ Competitive engines ________Previous engine ________ Expectations only ________ VE/VMS report ________NOTE: If the answer to number 3 is based on comparison (i.e. Other units in fleet, Competitive engines, Previous engine), the Customer Complaint Form and the Driveability/Low Power/Excessive Fuel Consumption – Checklist must be filled out for the comparison unit(s) in order to properly troubleshoot the complaint.
  4. When did the problem occur?Since New ________ Suddenly ________ Gradually ________
  5. Did the problem start after a repair? Yes ________ No ________If so, what was repaired and why? ____________________________________________________________
  6. Is the vehicle also experiencing a Driveability problem (Low Power orPoor Acceleration/Response)? Yes ________ No ________If number 6 is answered Yes, fill out the Driveability/Low Power/Excessive Fuel Consumption Checklist.
  7. Is the problem seasonal? Yes ________ No ________
  8. Weather conditions during fuel consumption check?Rain _____ Snow _____ Windy _____ Hot Temperatures _____ Cold Temperatures _____
  9. How is the fuel usage measured?Tank _____ Trip _____ Month _____ Year _____Road Relay _____ ECM _____ Inspec _____
  10. If number 9 is answered Road Relay, ECM, or Inspec, how do these fuel numbers compare to actual?Percent Difference ________
  11. If tractor pulls a refrigerated trailer, are fuel tickets kept separate for tractor and trailer fuel?Yes ________ No ________
  12. How is the distance measured?Hub _____ Odometer _____ Road Relay _____ ECM _____ Inspec _____ Map Miles _____ Dispatch/Paid Miles _____
  13. If number 12 is answered Road Relay, ECM, Inspec, Map, or Dispatch/Paid, how do these distance numbers compare to actual?Percent Difference ___________
  14. Are accurate records kept of fuel added on the road? Yes ________ No ________
  15. Do routes vary between compared vehicles? Yes ________ No ________
  16. Have routes changed for the engine being checked? Yes ________ No ________
  17. Has driver changed for the engine being checked? Yes ________ No ________
  18. Has typical load changed for the engine being checked? Yes ________ No ________
  19. Has the fuel source changed? Yes ________ No ________
  20. What are the loads hauled, compared to comparison unit? GVW _______________Heavier ________ Lighter ________
  21. At what altitude is the truck operating?Below 10,000 feet ________ Above 10,000 feet ________
  22. According to the driver, how many hours per day is the truck idling? Hours/day __________The Service Location should fill out the remaining sectionDistributor Name __________________________________________ Date __________________Distributor Contact _________________________________________ Distributor Phone Number __________________
  23. Record the following parameters from Trip Information in INSITE™:Version of INSITE™ used ______________Percent Time in Top Gear ______________%Percent Time One Gear Down ______________%Percent Time in Cruise Control ______________%Percent Time at Idle ______________%PTO Time ______________hrsTrip Distance ______________mi/kmTrip Fuel Used ______________gal/LTrip Gear Down Distance ______________mi/kmTrip Top Gear Distance ______________mi/kmCruise Control Distance ______________mi/kmVehicle Overspeed 1 Distance ______________mi/kmVehicle Overspeed 1 Threshold ______________mph/kphVehicle Overspeed 1 Time ______________hrsVehicle Overspeed 2 Distance ______________mi/kmVehicle Overspeed 2 Threshold ______________mph/kphVehicle Overspeed 2 Time ______________hrs
  24. Is the driver technique or operating practices affecting fuel economy?Incorrect shift rpm? Yes ________ No ________Rpm at cruise control speed? Yes ________ No ________Is customer compensating for low power? Yes ________ No ________
  25. Have fuel tank vents been verified to be working properly? Yes ________ No ________
  26. Has vehicle been checked for brake drag? Yes ________ No ________
  27. Has vehicle been checked for tractor and trailer alignment? Yes ________ No ________
  28. Has vehicle been checked for fuel leaks? Yes ________ No ________
  29. Does vehicle have either a fuel heater or cooler? Yes ________ No ________
  30. Is customer using proper fuel for ambient conditions? Yes ________ No ________
  31. Are all charge air cooler clamps present and tight? Yes ________ No ________

IF AFTER FILLING OUT THIS FORM IT APPEARS THAT THE PROBLEM IS NOT CAUSED BY VEHICLE FACTORS, ENVIRONMENTAL FACTORS, OR DRIVER TECHNIQUE, FILL OUT THE DRIVEABILITY/LOW POWER/EXCESSIVE FUEL CONSUMPTION CHECKLIST.

Oil Consumption

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In addition to the information that follows, a service publication is available titled Technical Overview of Oil Consumption, Bulletin 3379214.

SMALL | MEDIUM | LARGE

Engine Lubricating Oil Consumption Report
Owner’s Name
Engine Serial Number
Engine Model and Horsepower
Date of Delivery
Month
Day
Year
Address
Equipment Manufacturer
City
State/Province
Equipment Serial Number
Fuel Pump Serial Number
Engine Application (describe)
Oil and Filter Change Interval
Complaint Originally Registered
Oil
Filters
Date
Miles/Hours/Kilometers
Lubricating Oil Added 
Date Added Oil
Engine Operation
Miles/Hours/Kilometers
Oil Added
Liters/Quarts
Oil Used
Brand/Viscosity
Start Test
     
       
       
       
       
       
       
       
       
       
Last Mileage/Hours/Kilometers
Equals Test Mileage/Hours/Kilometers
Equals
Minus Start Mileage/Hours/Kilometers
Divided by Oil Added
Usage Rate
Customer Signature
Cummins® Dealer
Cummins® Distributor
Cummins Inc. Form 4755

Coolant Loss Pre-Troubleshooting Guide

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Before troubleshooting, it is critical to know where the coolant is being lost. It is not always obvious where the missing coolant has gone.

Before troubleshooting, it is important to determine the exact complaint by interviewing the driver, looking at the service history and looking at the ECM information.

Driver Interview Questions

Driver’s Name:

ESN:

What is your complaint?

How is this engine used?

What sort of load factors?

Where is the vehicle driven?

  1. How often do you add coolant?
  1. How do you fill the radiator?
  2. Do you fill to the High or Low mark when the engine is cold (less than 60°C [140°F])?
  3. What type of coolant do you add?
  4. Have you seen any coolant on the ground under your truck?
  5. Have you seen green or white streaks on the engine or near the coolant overflow hose?
  1. Is there any specific condition when you get indications of coolant loss (weather, altitude or load)?
  2. Does the engine ever overheat?
  3. Does the warning light flash?
  4. Under what condition?
  5. What temperature does the coolant run at normally?
  6. Does the cooling fan operate correctly (fan on at 99°C [210°F])?
  1. Have you seen any white smoke at operating temperature, or has anyone told you that white smoke is coming out of the exhaust?
  2. Do you have oil analysis performed as part of your maintenance?
  3. Are there elevated levels of sodium or potassium?
  4. Have you noticed any increase in moisture condensation on the dipstick or oil fill cap, or moisture in the blowby?
  5. Have you noticed a milky appearance in your lube oil that might indicate coolant is present?
  1. What other comments do you have that might help us make the right repair?

Service History Review

Repeat cylinder head or cylinder head gasket repairs can indicate the problem is likely not the cylinder head or cylinder head gasket. Repeat problems can indicate a deeper problem in the engine. Keep this information in mind while going through the troubleshooting procedure.

Look at this engine’s warranty claims history: who worked on the engine last and what did they do? How many miles/kilometers are on this engine? Has a cylinder head or cylinder head gasket been replaced before? At how many miles were the repairs made?

ECM Data Review

Print out an INSITE™ Image Report from the ECM. Look for high temperature alarms or low coolant level alarms. Either indication confirms a complaint of loosing coolant.

Are any fault codes logged in the Engine Protection Fault History?

  • ECM Fault Code 235 – Low Coolant (how many times)?
  • ECM Fault Code 151 – High Coolant Temperature (how many times)?

At this point, do you know where the coolant is going? If not and the coolant loss is not severe, suggest mounting a catch bottle on the radiator overflow tube to catch any overflow that can possibly be blowing out and becoming lost while at speed. Send the vehicle out to collect more data about where the coolant is or is not going. If the catch bottle has some coolant in it, refer back to the Coolant Loss External (out the overflow) interview questions.

Last Modified:  25-Jun-2010