Cummins NT Diesel Engines "A" Maintenance Checks – Weekly

Before performing the weekly maintenance checks of Cummins NT diesel engines, you should repeat daily checks.

Repeat Daily Checks (First step)

Then check air cleaner and clean pre-cleaner & dust pan

Under extremely dirty conditions an air pre-cleaner may be used. Clean the pre-cleaner jar and dry-type air cleaner dust pans daily or more often, as necessary, depending on operating conditions.

Check Air Inlet Restriction

Mechanical Indicator

A mechanical restriction indicator is available to indicate excessive air restriction through a dry type air cleaner.  This instrument can be mounted in the air cleaner outlet or on the vehicle instrument panel. The red flag in the window gradually rises as the cartridge loads with dirt. After changing or replacing the cartridge, reset the indicator by pushing the reset button.

Fig. 2-4. Air inlet restriction indicator

Note: Never remove the felt washer from the indicator. It is necessary to absorb moisture.

Vacuum Indicator

Vacuum switches, Fig.2-2, are available which actuate a warning light on the intrument panel when the air restriction becomes excessive.

Fig.2-5. Vacuum switch to check air inlet

 ① Wiring ② Piping ③ Vacuum Switch ④ Warning Light

Air restriction on turbocharged engines must not exceed 25 inches [635 mm] of water or 1.8 inches [46 mm] of mercury under full power conditions.

Clean or Replace Air Cleaner Element

The dust in the air is the main source of a diesel engine cylinder head, piston, piston rings, valve and valve guide as well as other moving parts wear,the greater the dust in the intake of diesel engine, the faster the diesel engine parts wear and tear. Therefore,  carefully choosing a air cleaner is very important to prolong the diesel engine’s service life.

According to different uses, the air cleaner used by Chongqing Cummins diesel engine is classified as light duty and heavy duty.

When it comes to cleaning air cleaner, pay attention to  the following details.

① Oil or water is not allowed to clean air cleaner element, otherwise, air cleaner hole is blocked, increase the air restriction; meanwhile, the diesel is easy to be sucked into the air cylinder, causing the starting speed after loading.

② The swirl tube is fixed with its housing and is not removable. It can be cleaned  with hot alkali water. Rinse it with clean water and then blow it down with compressed air.

③ The air cleaner element inside the heavy duty air cleaner (That is security air cleaner element) cannot be cleaned.

Caution: When any of the following problems occur, the cleaner element outside the air cleaner must be replaced.

1. The cleaner element has been damaged.

2. When installing the element that has been cleaned, the air inlet restriction indicator lamp is red.

3. The cleaning times of the cleaner element reach up to five times.

Caution:  For heavy duty air cleaner, it should be immediately replaced when the outlet air cleaner element is damaged or cleaned up to 5 times.

The paper element in a dry-type air cleaner , Fig’s. 2-9, 2-10, 2-11 and 2-12, may be cleaned several times by using compressed air to blow off dirt , approximately 30 psi [207 kPa]. Do not hold the air jet too close to the paper element.

Elements that have been cleaned several times will finally clog and air flow to the engine will be restricted. After cleaning, check the restriction as previously described and replace the element if necessary.

Caution: Holes, loose and seals, dented sealing surfaces and other forms of damage render the cleaner inoperative and require immediate element replacement.

To change the element:

1. Loosen the wing nut (1, Fig.2-6) securing the bottom cover (2) to the cleaner housing (3). Remove the cover.

2. Pull the element (6) down from the center bolt (4).

Fig. 2-6. Air cleaner - dry type

Fig. 2-7. Changing air cleaner element

Fig. 2-8. Air cleaner - heavy duty

Fig. 2-9. Air cleaner - heavy duty dual element

Caution: Pull the cover and the element straight out when removing them from the housing. Fig. 2-10, to avoid damage to the element.

3. Remove the gasket (5) from the outlet end (7) of the housing.

When installing the element, make sure it seats on the gasket at the air cleaner outlet end.

Drain Air Tanks

In cold weather, condensed moisture in the air tanks and lines may freeze and make controls useless.

Drain the air tanks to keep all water out of the compressed air system.

Drain Sediment from Fuel Tanks

Loosen the fuel tank drain cock or plug, if used, and drain approximately 1 cup of fuel to remove water and sediment. Close the drain cock or plug.

Fuel/Water Filter Separator

If more moisture than usual is present when checking the fuel tanks, it may be advisable to install a water separator.

Contact the nearest Cummins Dealer for a Fleet-guard water separator that meets requirements.

Drain plugs are located in the bottom of some fuel filter cases and in the sump of some fuel supply tanks. More condensation of water vapor occurs in a partially filled fuel tank than in a full one. Therefore, fuel supply tanks should be kept as nearly full as possible. Warm returning fuel from the injectors heats the fuel in the supply tank. If the fuel level is low in cold weather, the fact that the upper portion of the tank is not being heated by returning fuel trends to increase condensation. In warm weather both the supply tank and the fuel are warm. In the night, however, cool air lowers the temperature of the tank much more rapidly than the temperature of the fuel. Again this trends to increase condensation.

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