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Cummins ISM & QSM 11 Information+
We make the process of ordering parts for the Cummins ISM or QSM easy by separating by engine type. If you are unsure which type of engine you have, or for general information about your engine, locate the dataplate.
The dataplate will be located on the same side of the engine as the fuel pump. The far left column will show the model and serial number. The ISM will have the model number followed by a number, which is the advertised brakepower. For the QSM, the model will be followed by 11 (signifying the engine is 11 liters) followed by a dash and then the application (M for marine, C for construction, G for generator and A for agriculture) followed by a number, such as 335, which is the brake horsepower.
If you are experiencing problems with your QSM or ISM Cummins engine, the following can be used as a general guide for troubleshooting. As a reminder, be sure to only perform procedures which you feel comfortable with, and always trust an experienced Diesel mechanic for any major repairs or installations.
White smoke seen in exhaust
Use this as a guide for diagnosing excessive white smoke coming from the exhaust.
• This can be caused by an internal coolant leak. Check the fuel heater, if one is equipped. Then check the air compressor cylinder head, EGR and turbochager for any signs of leaking coolant. If these seem fine, check the cylinder liner for any cracks or signs of corrosion. Next, check the cylinder head gasket and the head itself for signs of coolant loss.
• If the engine is not using coolant then check the turbocharger to make sure the fins are not damaged. Check for any signs of air leaks around the turbocharger.
• If these areas seem fine, then each injector should be checked for leaks, or as a cause of the problem.
Excessive Vibration (Non-marine engines)
If your QSX or ISX Cummins engine is experiencing vibration that seems to be above normal, then this can be used as a guide to help find the cause of the problem.
• First check to make sure it is the main engine. Make sure the accessories are off, such as air-conditioning or PTO.
• Check the engine at idle. If it shuts off or runs rough, check the following areas. If it does not, go on to the next step. Check the sight glass on the fuel pump for any air bubbles. If there is, locate the source of the air leak in the system. Check all of the fuel lines to make sure they are not restricted or clogged. Check all sources of air intake to make sure they are working and not blocked, including the exhaust.
• Next check the engine mounts. If they show signs of shorting against the mounts then they need to be replaced. If they appear fine, proceed to the next step.
• Check the components, and make sure they are not touching the frame or body, including the clamps, exhaust, air intake piping and so on. If none can be found, slowly increase the RPM to see where the vibration is greatest and go on to the next step.
• Is the vibration is noticed only between 300 to 400 RPM? The likely problem is a structural component or a rotating component is out of balance.
• Does the vibration occur under the 300 to 400 RPM range? This can be corrected by disabling the PTO and other accessories to make sure they are not applying excessive strain and correctly installed. If they are, then check the drive belts for any signs of damage. Run the engine (briefly, careful not to overheat) without the belts and check to see if they were the source. If these are fine, check any structural modifications and disconnect, such as snow plows, bumpers, etc. If none of these alleviate the vibration, check or replace the engine mount isolators, engine mount brackets or engine mount isolators.
• Does the vibration occur above 400 RPM but under 1050 RPM? In addition to checking the belts and mounts, also check the vibration damper to make sure it does not show any signs of warping. If it appears fine, then check the air compressor to make sure it is working correctly. If these seem fine, check the hydraulic pump and compressor, especially any gear driven components for being the cause. If this is not the cause, check the PTO by disconnecting it and monitoring to see if the vibration stops. If this is not the cause, try engaging and disengaging the clutch to see if the clutch is causing the problem. If the vibration is still present, check the flywheel for any damage or signs of being unbalanced. If it appears fine, and the engine has always had the problem (since it was new or after replacing the crankshaft) then turn off the engine and remove the lubricating oil pan. The crankshaft may be unbalanced and should be replaced.
• Does the vibration occur above 1050 RPM only? Start with a road test to see where the vibration starts and place the transmission in neutral. If it is not present in neutral, then check the engine mount isolators for wear, and the engine mount brackets for proper alignment. If it is only present when the transmission is in neutral, then it could be a problem with the drive train.
• Is the vibration occurring in a marine engine? Check the gear ratio and the propeller to make sure it is correctly matched. If they are, check the engine mounts and isolators for any signs of wear or damage. If they are fine, next check the exhaust system to make sure it is working correctly and able to draw the exhaust away from the engine. Next, check the accessories, but do NOT operate without the sea water pump connected. If the vibration cannot be isolated to a certain accessory, then proceed to check the propeller shaft to make sure it is straight. Run the engine without the drive shaft attached to the coupler to check. If the vibration still persists, check the strut cutlass bearing to see if it is misaligned or stiff. Next, check the v-angle on the v-strut to make sure it matches the angle of the propeller's blade. Then, check that the propeller tunnels and torsional coupling are the correct size and not showing any signs of wear.
When to rebuild your engine
For the ISM or QSM Cummins engine, a periodic rebuild is necessary with long-term use. Listed here are some signs to look for when the engine is disassembled.
• The connecting rod bearing or their saddles have pits, flakes or other signs of corrosion. Some wear is normal, which will expose the copper lining underneath. If this happens when the engine has less than 150,000 miles or 3750 hours, then it needs to be replaced. For the bearing, the minimum thickness is 0.0957 inch, and should be replaced if below this value.
• The bearing shell has deep scratches, nicks or other signs of irreparable damage. The minimum thickness is 0.1533 inches.
• Main bearing shell shows signs of fretting, which gives it the appearance of being frosted, or the texture of an orange peel.
• The cylinder liners have cracks on the inside that are deep enough to catch a fingernail on. If the outside diameter has corrosion, or pits that are deeper than 0.060 inches deep.
• The o-rings show any sign of leaking or damage.
• The piston crown, or skirt, is loose or has cracks.
Fixing Air in the Fuel
For the Cummins ISM and QSM, air in the fuel system can cause many problems. These include slow deceleration to poor performance. Air can cause the fuel to have a milky appearance. If you suspect you have this condition in your engine, use the following as a guide to repair:
• If you are unsure and would like to perform a test, first remove the gear pump cooling drain line, and attach a hose to it. Plug the fuel pump suction line. Place the other end of the hose in a container that has fuel in it, such as a clear glass. This will push fuel from the system into the cup. Run the engine at high idle with no load. If you do not see bubbles then the system is fine, if you do, then air is entering the system somewhere.
• First, tighten the fuel supply pump inlet fitting. Then, tighten the cooling plate inlet and outlet fittings.
• Then, tighten the fuel filter and the hose connections. Locate the drop tube in the fuel tank and make sure it is not damaged. Then, if you attached a hose to test the system, remove the plug and reattach the drain.
General Information and Specifications
Listed here are the Cummins ISM specifications, along with some general info, for your reference.
Displacement: 10.8 liters.
Minimum fuel pressure during cranking: 25 psi.
Minimum fuel pressure at 1200 RPM: 120 psi.
Oil pressure minimum at idle (automotive): 30 psi.
Oil pressure minimum at 1200 RPM (automotive): 30 psi.
Oil capacity (automotive): 7 to 9 gallons.
Oil capacity (transit bus): 8 to 9 gallons.
Coolant capacity: 10-12.4 quarts.
Coolant pressure, minimum at 1800 RPM with a closed thermostat: 20 psi.
Coolant pressure, maximum with closed thermostat: 40 psi.
Coolant temperature (minimum/maximum): 160 to 212 degrees F.
Cummins QSM Marine Specs and Information
Listed below are the general specifications for the marine parts.
Maximum fuel inlet temperature: 160 degrees F.
Oil pressure minimum at idle: 10 psi.
Oil pressure range: 30 to 65 psi.
Oil pressure minimum at 1200 RPM: 30 psi.
Oil capacity: 7-8 gallons.
Coolant capacity (with heat exchanger): 8 gallons.
Maximum coolant temperature: 205 degrees F.
Maximum angularity of oil pan (front down): 30 degrees for the rear sump, 45 degrees for the front sump.
Maximum angularity of oil pan (rear down): 25 degrees for the rear sump, 27 degrees for the front sump.
Maximum angularity of oil pan (side to side): 30 degrees for the rear sump, 42 degrees for the front sump.
Cummins QSM11 Parts +
What are the general specs of the Cummins QSM11?
This engine has a bore of 4.92 inches, a stroke of 5.79 inches and a displacement of 10.8 liters.
What is the maximum allowable radial load (angle) on the crankshaft?
At 0 degrees: 192 lb.
At 90 degrees: 90 lb.
At 180 degrees: 1106 lb.
At 270 degrees: 192 lb.
What is the engine pitch angle for steady state operation during vessel operation?
Proper engine angles can prevent the unnecessary wear and tear (or malfunction) of many vital engine parts and operations.
Front up from horizontal:
-15 degrees minimum / 31 degrees maximum.
What is the engine pitch angle for intermittent vessel operation?
When viewed from flywheel side of engine - From right/left:
45 degrees maximum right or 37 degrees left (roll angle).
What are the Cummins QSM11 fuel system specs?
Max allowable restriction to the fuel pump: is 6 in Hg / 10 in Hg (clean filter / dirty filter.)
Return line pressure: 6.5 in Hg maximum.
Static pressure at fuel pump: 6 in Hg.
Fuel pump height, above fuel pump: 2.47 m or 8.1 feet.
What are the exhaust system specs for the QSM11?
Problems with the exhaust system can cause many parts to malfunction on a Cummins QSM11. Be sure to always check if you are experiencing performance issues.
3 in Hg - Maximum allowable back pressure
20 lb maximum incremental direct load at the turbine outlet mounting flange.
What are the air intake specs for the QSM11?
Correctly identifying air intake problems can help you identify which parts need to be replaced, and is recommended for any major engine overhauls.
The maximum air cleaner inlet tmperature rise over the ambient temperature is 30 degrees F.
The maximum air intake restriction with a clean filter is 10 in H2O with a clean filter and 25 in H2O for a dirty filter.