3306 DIESEL TRUCK ENGINE Caterpillar


Difficult Starting - Engine Crankshaft Turns Freely

Usage:

Exhaust Smoke Can Be Seen While Starting

Recommended Procedure

1. Cold Outside Temperatures ... It can be necessary to use starting aids, or to heat engine oil or coolant at temperatures below 50°F (10°C).
2. Air in Fuel System ... With air in the fuel system, the engine will normally be difficult to start, run rough, and release a large amount of white smoke. If the engine will not start, loosen a fuel injection line nut at the cylinder head. With the governor lever in the shutoff position, operate the fuel priming pump until the flow of fuel from the loosened fuel injection line is free of air. Tighten the fuel line nut. Fasten the priming pump and start the engine. If the engine still does not run smooth or releases a large amount of white smoke, loosen the fuel line nuts one at a time at the cylinder head until the fuel that comes out is free of air. Tighten the fuel line nuts. If the air can not be removed in this way, put 5 psi (35 kPa) of air pressure to the fuel tank.


NOTICE

Do not use more than 8 psi (55 kPa) of air pressure in the fuel tank or damage to the tank may result.


Check for leakage at the connections between the fuel tank and the fuel transfer pump. If leaks are found, tighten the connections or replace the lines. If there are no visual leaks, remove the fuel supply line from the tank and connect it to an outside fuel supply. If this corrects the problem, the suction line (standpipe) inside the fuel tank has a leak.

3. Low Quality Fuel ... Remove a small amount of fuel from the tank and check for water in the fuel. If there is water in the fuel, remove fuel from the tank until it is free of water and fill with a good quality fuel. Change the fuel filter and "prime" (remove the air and/or low quality fuel from the fuel system) the fuel system with the fuel priming pump. If there is no water in the fuel, prime and start the engine by using an outside source of fuel. If engine starts correctly using different fuel, remove all fuel from the tank and fill with good quality fuel. Prime the fuel system if necessary.
4. Low Fuel Pressure ... Change the fuel filter. If the pressure is still low, check the bypass valve in the fuel transfer pump. Debris in the system can make the valve become stationary in the open position.
5. Fuel Injection Timing Not Correct ... Check and make necessary adjustments as per Testing and Adjusting section of this Service Manual.
6. Valve Adjustment Not Correct ... Check and make necessary adjustments as per Testing and Adjusting section of this Service Manual. Intake valve clearance is .015 in. (0.38 mm) and exhaust valve clearance is .025 in. (0.64 mm).
7. Bad Fuel Nozzle(s) ... Remove the fuel nozzles and test as per Testing and Adjusting section of this Service Manual.
8. Low Compression ... See Misfiring and Running Rough.

Exhaust Smoke Can Not Be Seen While Starting

9. No Fuel in Tank(s) ... Check fuel level visually (do not use the fuel gauge only). Be sure tank selection valve is open to the tank with fuel in it. Be sure valve in fuel line between the tanks is open.
10. No Fuel From Fuel Injection Pump ... Loosen a fuel injection line nut at the pump housing. With ignition switch in the ON position and accelerator in the FUEL ON position, turn the engine with the starter to be sure there is no fuel from the fuel injection pump. To find the cause for no fuel, follow Steps (a) through (d) until the problem is corrected.

a. Prime the fuel system as shown in Procedure No. 2.

b. Check shut-off solenoid by turning ignition switch to ON position. You must hear a sound when the plunger opens. If no sound is heard, make sure there is battery voltage at the solenoid. If the solenoid does not work, install a new solenoid.

c. If you are not using a good quality of fuel at temperatures below 10°F (-12°C), it is possible that the fuel in the system can "wax" (not have correct flow characteristics) and cause a restriction in the fuel system. Install a new fuel filter. It may be necessary to drain the complete fuel system and replace with a No. 1 grade of fuel.

d. Check for fuel supply line restriction by removing the fuel supply line for the fuel filter base. Put 5 psi (35 kPa) of air pressure to the fuel tank.


NOTICE

Do not use more than 8 psi (55 kPa) of air pressure in the fuel tank or damage to the tank may result.


If there is no fuel, or only a weak flow of fuel from the fuel supply line, there is a restriction in the fuel supply line and/or the fuel tank.

11. Exhaust System Not Open ... Loosen the exhaust pipe from the exhaust manifold. If engine will now start, check the exhaust system for damage and/or restrictions.
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