Cummins Engine "D" Maintenance Checks

We have talked about Cummins NT series diesel engine maintenance checks of “A”, “B” and “C” in previous article. In this article, you will learn “D” maintenance checks of Cummins engine. If you are looking for the knowledge, why not take a few time to read it?

At each “D” Maintenance Checks, perform all “A”, “B” and “C” checks in addition to those following. Most of these checks should be performed by a Cummins Distributor or Dealer and where Cummins Shop Manuals are available for complete instructions.

Clean and Calibrate Injectors

Clean and calibrate the injectors regularly to prevent restriction of fuel delivery to the combustion chambers. Because of the special tools required for calibration, most owners and fleets find it more economical to let a Cummins Distributor do the cleaning and calibration operations.

To clean and calibrate the injectors from Engines for cleaning the seal seat should be removed from the injector (1, Fig.2-22) or injector “well” for cleaning, examination and or replacement as necessary.

Caution: There must be only one seal seat used in each injector “well”. Use of more than one seal seat per injector will change the injector protrusion and cause combustion inefficiency.

Clean and Calibrate Fuel Pump

Check the fuel pump calibration on the engine if required.

Inspect Water Pump, Fan Hub and Idler Pulley

Inspect the water pump shaft, fan buh and idler for wobble and evidence of grease leakage. Refer to the engine shop manual for rebuild and lubricating procedure for these assemblies.

Inspect Turbocharger

Check Turbocharger Bearing Clearance

Check bearing clearances. This can be done without removing the turbocharger from the engine, by using a dial indicator to indicate the end-play of the rotor shaft and a feeler gauge to indicate the radial clearance. Fig. 2-23.

Fig.2-23. Check turbocharger bearing end clearance.

Checking Procedure

1. Removing the exhaust and intake piping from the turbocharger to expose the ends of the rotor assembly.

2. Remove one capscrew from the front plate (compressor wheel end) and replace it with a long capscrew. Attach an indicator to the long capscrew and register the indicator point on the end of the rotor shaft. Push the shaft from end-to-end making note of the total indicator reading. On HT3B the end clearance should be 0.0020 to 0.0070 inch [0.051 to 0.178 mm].

a. Push the wheel toward the side of the bore.

b. Using a feeler gauge, check the distance between the tip of the wheel vanes and the bore. On HT3B the clearance should be 0.00150 to 0.00230 inch [0.381 to 0.584 mm].

3. Check the radial clearance on the compressor wheel only.

4. If end clearances exceed the limits, remove the turbocharger from the engine and replace it with a new or rebuild unit.

5. Install the exhaust and intake piping to the turbocharger(s).

Inspect Vibration Damper

Vibration

Check the damper for evidence of fluid loss, dents and wobble. Visually inspect the vibration damper’s thickness for any deformation or raising of the damper’s front cover plate.

1. If a lack of space around the damper will not permit a visual inspection, run a finger around the inside and the outside of the front cover plate. If any variations or deformations are detected, remove the vibration damper and check as follows.

2. Remove paint, dirt and grime from the front and rear surface of the damper in four equal spaced areas. Clean the surface with paint solvent and fine emery cloth.

3. Using a micrometer measure and record the thickness of the dampers at the four areas approximately 0.125 inch [3.18 mm] from the outside edge of the front cover plate.

4. Replace the damper if the variation of the four readings exceed 0.001 inch [0.25 mm].

Air Compressor

Inspect compressor for the evidence of oil and coolant leakage and oil carry cover in the air compressor pistion. Replace it with a rebuilt unit as necessary.

Attentions: Engine maintenance is very important for a generator set no matter what brand of generator. Regular maintenance not only prolongs the engine's service life, but also cut the cost.