4M40 DIESEL ENGINE SHOP MANUAL General Caterpillar

1.1. Engine Number, Engine Name Plate
2.1. How To Read This Manual
3.2. Structure of This Shop Manual
4.2. Terminology
5.2. Tightening Torques
6.2. Units
7.2. How To Read This Manual
8.1. General Work
9.2. Part Measurement Methods
10.2. Evaluation of Oil Leakage
11.1. Precautions For Maintenance Operation
12.2. General Precautions
13.2. Precautions for Electrical System
14.2. Precautions for Arc Welding

Engine Number, Engine Name Plate

* Serial engine numbers are assigned to the engines in manufacturing sequence. Every engine has its own number. These numbers are required for registration and related inspection of the vehicle.

*An engine name plate indicates the following item.

* Engine model

How To Read This Manual

Structure of This Shop Manual


Tightening Torques

* Tightening torques are broadly classified as follows:
* Bolts and nuts for which tightening torques are specified regardless of installation location are referred to as "standard" bolts and nuts, and their tightening torques are referred to as "standard" tightening torques. (Standard tightening torques are specified in accordance with the sizes and materials of threaded parts.) Identify standard bolts and nuts by comparing them with the following standard tightening torque table. The tightening torques for standard bolts and nuts are shown in this table, and not particularly shown in the text.
* The tightening torque for any bolt or nut that is not subject to a standard tightening torque or cannot be identified from the following table is shown in the text.
* Any bolt or nut indicated as "wet" must be tightened in a wet condition (with engine oil or grease applied). Any other item must be tightened in a dry condition.

Standard tightening torque table

* Use the specified bolts and nuts. Except where otherwise specified, tighten them to the torques shown in the following table.
* The threads and seating surfaces must be dry.
* If a mating nut and a bolt (or stud bolt) have different strength classifications, tighten to the torque shown for the bolt.

(1) Hexagon head bolts and stud bolts (Unit: N·m {kgf·m}

(2) Hexagon head flange bolts (Unit: N·m {kgf·m}

(3) Hexagon nuts (Unit: N·m {kgf·m}

(4) Hexagon flange nuts (Unit: N·m {kgf·m}

(5) Tightening torque for general-purpose flare nut (Unit: N·m {kgf·m}

(6) Tightening torque for general-purpose air piping nylon tube (DIN type) (Unit: N·m {kgf·m}

(7) Tightening torque for general-purpose air piping nylon tube (SAE type) (Unit: N·m {kgf·m}


* Tightening torques and other parameters are given in SI* units with metric units added in brackets { }/ Values in engine specifications, performance curves, and other items taken from official approval documents are given only in metric units.

How To Read This Manual

General Work

Part Measurement Methods

* Pay close attention to the following points when measuring parts.

Shaft-to-hole clearance measurement, and good/bad evaluation

* Where a shaft-to-hole clearance is specified as a service standard, measurement and good/bad evaluation must be performed as follows:
* Choose at least two measurement locations along the length of the shaft. Add measurement locations depending on the length of the shaft. The following example assumes three measurement locations.
* At each measurement location (a, b, and c), measure the shaft diameter and hole diameter in two directions perpendicular to each other. Note the smaller shaft measurement (min) and larger hole measurement (max) at each measurement location.

Shaft: da min, db min, dc min

Hole: Da max, Db max, Dc max

* For each of the three measurement locations (a, b, and c), subtract the smaller (noted) shaft diameter from the larger (noted) hole diameter to determine the clearance.

Clearance a= Da max - da min

Clearance b= Db max - db min

Clearance c= Dc max - dc min

* Compare the biggest of the clearances with the service standard (standard value or limit). If the clearance exceeds the service standard (standard value or limit), replace the defective part (the shaft or the part containing the hole).


If clearance a > clearance b > clearance c, then clearance a is the biggest one (clearance max).

If clearance max > service standard (standard value or limit), then the clearance is not acceptable.

Shaft deflection and bend

* The deflection of a shaft is the indication given by a needle of a dial gauge after one rotation of the shaft. Half of the deflection is the extend of bend.

Measurement of springs

* To take a load measurement with a compression spring, use a spring tester to measure the load with the spring at its installed length as illustrated. To take a load measurement with an extension spring, use a spring balance to measure the load with the spring at its installed length as illustrated.
* To measure the squareness of a compression spring, place the spring on a surface plate, standing against an engineer's square. Turn the spring once. Measure the clearance between the end of the spring and the square where it is greatest. This value is the squareness.

Evaluation of Oil Leakage

* Specific instructions for inspecting and evaluating oil leakage are given in certain inspection procedures. In general, however, the following conditions are used in criteria:
* Externally dry: Seals, gaskets, and joints are complete and externally dry.
* Oozing: Seals, gaskets, and surrounding areas are moist.
* Collecting: Oil droplets have accumulated, but there is no visible dripping.
* Dripping: Oil is dripping in sufficient quantity to make a mark on the floor.

Precautions For Maintenance Operation

* Before performing service operations, inquire the operating conditions and the customer's demand on site and record the necessary information to judge the condition of the engine correctly. Based on that information, perform the efficient and effective maintenance.
* Check the location of the fault, and identify its cause. Based on your findings, determine whether parts must be removed or disassembled. Then, follow the service procedure given in this manual.

General Precautions

* The service operations should be performed on a flat place. Prepare all the general and special tools necessary for the job.

------ WARNING! ------

* Special tools must be used wherever specified in this manual. Do not attempt to use other tools since they could cause injuries and/or vehicle damage.

* Take extreme care when removing/installing heavy items such as engine. When lifting heavy items using a cable, etc., observe the following precautions.

* Identify the mass of the item being lifted. Use a cable that is strong enough to support the mass.
* If lifting eyes are not provided on the item being lifted, tie a cable around the item taking into account the item's center of gravity.

* Never work in shoes that have oily soles. When working with a partner or in a group, use pre-arranged signals and pay constant attention to safety. Be careful not to touch switches and levers unintentionally.

* Inspect for oil leakage, etc. before washing the parts. If the order is reversed, any oil leakage or fault that may exists could go unnoticed during inspection.
* Prepare replacement parts ready for installation.

* Oil seals, packings, O-rings and other rubber parts, gaskets, and split pins must be replaced with new ones after removal. Use only genuine MITSUBISHI replacement parts.

* When disassembling parts, visually check them for wear, cracks, damage, deformation, deterioration, rust, corrosion, defective rotation, fatigue, clogging and any other possible defect.

* To facilitate correct reassembly of parts, make alignment marks on them before disassembly and arrange disassembled parts neatly. Make punch marks and other alignment marks where they will not detract from parts' functionality and appearance.

* After removing parts from the vehicle, cover the area to keep it free of dust.
* Be careful not to mix up identical parts, similar parts and parts have left/right alignments.
* Keep new replacement parts and original (removed) parts separately.
* Apply the specified oil or grease to U-seals, oil seals, dust seals and bearings before reassembly.

* Always use the specified oils and greases when performing inspection or replacement. Immediately wipe away any excess oil or grease with a rag.
* Wear safety goggles when using a grinder or welder. Wear gloves when necessary, and watch out for sharp edges and other items that might wound your hands.

Precautions for Electrical System

* Before working on the electrical system, disconnect the (-) battery cable to prevent short circuits.

------ WARNING! ------

* Make sure the electrical equipment is OFF before disconnecting or connecting battery cable. Semiconductor components may otherwise be damaged.

* Carefully handle sensors relays, and other items that are sensitive to shock and heat.

* When applying a voltage to a part for inspection purposes, check that the (+) and (-) cables are connected properly then gradually increase the voltage from zero. Do not exceed the specified voltage. Remember that sensors do not necessarily operate on the battery voltage.

* When separating connectors, grasp the connectors themselves rather than the harnesses.

* To separate locking connectors, first push them in the direction of the arrows. To reconnect locking connectors, push them together until they click.
* Before washing the parts, cover electrical parts to keep them dry. (Use plastic sheets or the like.) Keep water away from harness connectors and sensors and immediately wipe off any water that gets on them.

Handling precautions for electric circuits

------ WARNING! ------

* Do not pierce wire insulation with test probes or alligator clips when performing electrical inspections. Doing so can, particularly with the chassis harness, hasten corrosion.

(1) Inspection of harnesses

(1.1) Inspections with connectors fitted together

* Waterproof connectors
* Connect an inspection harness and connector. A between the connectors B of the circuit to be inspected. Perform the inspection by applying a test probe C to the connectors of the inspection harness. Do not insert the test probe C into the wire-entry sides of the waterproof connectors since this would damage their waterproof seals and lead to rust.

* Non-waterproof connectors
* Perform the inspection by inserting a test probe C into the wire-entry sides of the connectors. An extra-narrow probe is required for control unit connectors, which are smaller than other types of connector. Do not force a regular-size probe into control unit connectors since this would cause damage.

(1.2) Inspections with connectors separated

* Inspections on female terminals
* Perform the inspection by carefully inserting a test probe into the terminals. Do not force the test probe into the terminals since this could deform them and cause poor connections.

* Inspections on male terminals
* Perform the inspection by applying test probes directly to the pins.

------ WARNING! ------

* Be careful not to short-circuit pins together with the test probes. With control unit connectors, short-circuiting of pins can cause damage to the control unit's internal circuitry.
* When using a multimeter to check continuity, do not allow the test probes to touch the wrong terminals.

(2) Inspection of connectors

(2.1) Visual inspection

* Check that the connectors are fitted together securely.

* Check whether wires have been separated from their terminals due to pulling of the harness.

* Check that male and female terminals fit together tightly.

* Check for defective connections caused by loose terminals, by rust on terminals, or by contamination of terminals by foreign substances.

(2.2) Checking for loose terminals

* If connector terminal retainers become damaged, male and female terminals may not mate with each other when the connector bodies are fitted together. To check for such terminals, gently pull each wire and see whether any terminals slip out of their connector housings.

(3) Inspections when a fuse blows

* Remove the fuse, then measure the resistance between ground and the fuses's load side. Next, close the switch of each circuit connected to the fuse. If the resistance measurement between any switch and ground is zero, there is a short-circuit between the switch and the load. If the resistance measurement is not zero, the circuit is not currently short-circuited; the fuse probably blew due to a momentary short circuit.

* The main causes of short circuits are as follows:
* Harnesses trapped between parts
* Harness insulation damage due to friction or heat
* Moisture in connectors or circuitry
* Human error (accidental short-circuiting of components)

(2.2) Service Precautions for alternators

* When servicing alternators, observe the following precautions:
* Never reverse the polarity of battery connections. If the polarity of the battery connections were to be reversed, a large current would flow from the battery to the alternator, damaging the diodes and regulator.

* Never disconnect the battery cables with the engine running. Disconnection of the battery cables during engine operation would cause a surge voltage, leading to deterioration of the diodes and regulator.

* Never perform inspections using a high-voltage multimeter. The use of a high-voltage multimeter could damage the diodes and regulator.

* Keep alternators dry. Water on alternators can cause internal short circuits and damage.

* Never operate an alternator with the B and L terminals short-circuited. Operation with the B and L terminals connected together would damage diode trio.

* Disconnect the battery cables before quick-changing the battery with a quick charger. Unless the battery cables are disconnected, quick-charging can damage the diodes and regulator.

Precautions for Arc Welding

* When arc welding is performed, current from the welder flows to ground via the machine metal parts. Unless appropriate steps are taken, this current can damage control units, other electrical devices and wiring harnesses. And any electrical device near the point on the vehicle to which the (-) cable of the welder is connected, might be largely damaged.

* The current of the welder will flow backward through the battery's (-) cable and damage the battery and electrical systems directly connected to the battery. Be sure to disconnect the battery's (-) cable in the following procedure.

* Turn the battery switch to the OFF position.
* Wait for two minutes.
* Disconnect the battery's (-) cable.
* Cover all parts of the machine that may be damaged by welding sparks,
* Connect the welder's (-) cable to the machine as close as possible to the area being welded.
* Set the welding current in accordance with the part being welded.

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