Common engine Troubles

Diesel Engine

Internal Combustion Engine are heat engines. There are moving and stationary parts made up of metal and that regardless of how good the lubrication and cooling system are, normal wear of parts will occur because of friction. It is important for any operator of the automotive vehicle to be sensitive to even minimal of the change in the vibration, color of the exhaust gases being emitted in the muffler to the atmosphere, power output and many others.

Some of the most common troubles are as follows:

Engine Lacks of Power

     This is a general compliant that is often difficult to analyzed because of a wide area of possible causes such as defective ignition system, defective fuel system, heavy oil or causes brought about by the lubricating system, etc. the most common procedure is to do tune-ups and isolate as to the loss or lack of power occurs when engine is hot and cold. For purposes of this topic however, we will limit the diagnosis to causes due mainly from the engine itself as the other troubles shall be discussed in the other part.

The most probable causes of an engine which general lacks power in operation are as follows:

1. Loss of compression
2. Excessive carbon in engine
3. Engine valves stuck open
4. Defective valve action

With the following causes mentioned above, the corrections to be undertaken are as follows:

     Find out the origin of compression leakage with the use of cylinder compression tester or cylinder leakage tester to determine if the leakage is due to the following:

1. Leakage past the piston rings or worn out piston ring. If this; is the reason, remove piston and ring assembly and replace piston ring.
2. Leakage is due to broken valve springs. Replace.
3. Leakage is due to worn out cylinders. Check and rebore or replace sleeve if necessary.
4. Leakage is due to worn out piston. Check and replace.
5. Leakage is due to worn out cylinder head gasket. Check and replace.
6. leakage is due to cracked cylinder head.

Compression Tester

     In all of these cylinders head must be removed, cleaned, inspected and repaired or replace as it is necessary. For gasoline engine compression pressure should not be less than 75 psi depending the compression ratio. always refer to manual of specifications.

      If after removing and dismantling the engine parts, excessive carbon is evident particularly in the combustion chamber piston head and valves, clean it thoroughly with solvent.

         If the engine valves stuck up in open position the valves and valve gear should be removed, service the valve stems, guides as needed. Check the valve face and seat fitness and replace the valve and valve guide as maybe required.

          Defective valve action can be tested with the compression leakage test and vacuum test. Any part of the valve assembly found defective should be replaced or repaired.

           As mentioned earlier there are other possible causes of troubles brought by other system but the discussion here is limited only to those most nearly caused by engine and its parts.

In all these, the manufacturers manual must be followed.

Engine Run but Misses on One Cylinder

     A missing engine is a rough engine. If one or more cylinders fail to fire or fire intermittently, the engine becomes out of balance, the result is rough engine operation and considerable loss of power. A missing engine is not easy to locate and remedy especially if the symptom is not causes by electrically. The use of testing equipment however can facilitate locating the causes of missing area as follow:

1. Valve stuck open
2. Broken valve spring 
3. Burned valves
4. Bent push rod
5. Flat cam lobe
6. Defective piston or rings
7. Defective head gasket
8. Loss of compression

     On the basis of the following causes, remedies to be undertaken are as follows:

     If the engine valves are stuck up in open position, the valve gear should be removed, cleaned thoroughly and servicing, repair or replacement done if the valve stem guide , valve stem are defective or if the push rods are bent, there is flat cam lobe, broken valve springs or burned valves, all these parts should be replaced. The valve face fitness to its seat must also be checked and if found not fitted, the valve face should be grinned to its seat.

     For defective piston rings or piston, loose compression will likely occur therefore less power. For defective head gasket, cylinder head should be removed, throughly cleaned and the damage cylinder head gasket removed and replaced with a new one. Check the combustion chamber, piston head and valve head for carbon deposit. Clean throughly with solvent. Replace worn-part piston and broken piston rings(or wear those with wide card gap).

      If the trouble is due to compression leakage proceed as cited in the previous trouble, that is, to find out first the origin of the compression leakage with the use of compression tester or cylinder leakage tester. After isolating the main origin of compression losses, remedy as mentioned previously.

      In disassembling (removing) engine parts, the engine manual must be consulted.

Engine Noises

     an engine noises may be a regular clicking, a pinging sound during load or acceleration, light knock or pound, light metallic double knock usually heard during idle chattering or rattling noise during acceleration, mellow or muffled bell like sound when the engine is cold and other kinds of noises.

If these are the kinds of noise heard, the most probalbe cause in the order mentioned are:

1. Valve and tappet clearance is too big.
2. Detonation or pinging sound is due to low octane fuel. these is too much carbon tahat results to advanced ignition timing.
3. worn connecting rod bearings or crankpin, mis-aligned rod or lack of oil.
4. Worn or loose pin or lack of oil.
5. worn rings or cylinder walls, low ring tension or broken rings.
6. Piston slap due to worn piston or walls, collapsed piston skirts excessive clearance, misaligned connecting rods or lack of oil.
7. Regular noise means worn main bearings; irregular noise is worn thrust bearing knock.
8. Loosely mounted accessories like the alternator, oil pan, front bumper, water pump, etc.

To remedy the foregoing , the following should be done:

1. Readjust valve tappet clearance to specification or replace noisy hydraulic lifters.
2. Use higher-octane fuel; remove carbon and adjust ignition timing.
3. Replace bearings, service crankpins; replace rod; add oil.
4. Service pin and bushing: add iol.
5. service walls; replace rings.
6. replace or resize piston; service walls; replace rod; add oil.
7. replace or service bearings and crankshaft.
8. Tighten mounting.

     In approaching this kind of trouble, the use of a listening rod or stethoscope is found helpful. this is similar in function to the doctor's stethoscope. when one end is placed at the ear and the other end at some part of engine is curve along the rod to the ear. When using this, touch the end of the rod to various places on the engine . Move it around to determine where and what ever to keep away from the moving fan belt and fan when using the listening rod.

Engine Backfires

     engine backfires may be caused by excessive carbon in the engine for it retains so much heart that can pre-ignite the air-fuel mixture as it enters the cylinder: Carbon also increases the compression ratio and thus the tendency for detonation so that they have sharp edges, valves that seat poorly, or valves that are carboned so that they overheat often procedure back firing.


Engine Piston Broken

   The possible cause of broken engine piston maybe any of the following:


Possible Cause:                                   Remedies:                

  1.)Undersize  piston                                1.) Use only the appropriate size of piston(standard average .           .                             size)recondition cylinder walls.

    

    2.) Eccentric or tapered cylinders.            2). Reconditioning cylinder walls and fit new piston and rings.

    3.)Misaligned or bent connecting              3.) Realign connecting rods.

       rods                                           

     4.)Engine overheating.                              4.) See possible cause and remedies of engine over heating as                                                                                                                                                                    .                                                                   mentioned earlier.

     5.)