AD-302 Car Driving DAE Chapter 5

 CHAPTER NO -5

Starting of an Engine.

Setting position of choke on

To start the cold petrol engine rich air fuel mixture is needed. Choke valve is used to provide this rich mixture. Choke valve is fitted between air cleaner and main discharge nozzle when the choke valve is closed main discharge nozzle provides rich mixture to the engine.

In case of manual choke driver pulls a knob and choked the throttle valve. In case of automatic choke, choke valve closed after the few minute of ignition switch off

What is a glow plug?

A glow plug is a heating element that heats incoming fuel and air to encourage efficient fuel combustion in a diesel engine. The fuel combustion starts your engine so that you can drive. Each cylinder of your engine has one glow plug, either in the pre-chamber (pre-chambered engines) or in the combustion chamber (direct-injection engines).

How long do glow plugs take to heat up?

Glow plugs continue to be heated for approximately 3 minutes after the engine has been started. This extended glow plug operating time helps to complete the combustion process and to decrease noise output as the combustion chambers heat up.

The battery light on your car dashboard signals a charging problem with your car battery. If the light turns and stays on, it might be that your alternator isn't generating enough voltage   to charge it. Common causes can be a broken alternator belt, damaged battery cells or a failed alternator.

Ignition key switch positions

1.  Lock – First Position

It is the first position of the ignition switch. The manufacturers describe lock as the OFF position. You have to rotate the key clockwise to turn on the ignition switch. The lock position is to insert the keys only. There is no effect on the steering wheel or other accessories in the lock position. You can take the keys out only in the lock position. You have to rotate the key clockwise to turn on the ignition switch.

2.  Accessory/ Acc – Second Position

Wondering what does acc stand for in cars ignition system? It is the accessory mode. You can use some of the standard accessories in this mode. Accessory or Acc is the second position in the ignition switch. Acc gives life to the radio, stereo, power windows, and seats.

3.  ON Or Ignition – Third Position

 

The next one is the ignition position. All the electronic accessories come active when you turn on the ignition switch in this mode. According to the expert maintenance tips, the ON position is the default position in vehicles. You cannot remove the keys out from the ignition switch.

4.  Start – Fourth Position

Now you can crank the engine. It is not the stopping position of the ignition system. The keys move back to ON or ignition, which is the default position. The motor starter might damage if you stop the keys here for long. Let the keys turn to default position once the engine starts.

Describe engine warm up period

The warm up time is considered as the time taken for the coolant temperature to reach the minimum coolant temperature of a well-functioning engine, which is around 80 °C. The idle test is conducted in cold-start condition to have extra information on warm up and fuel consumption of a non-moving vehicle.

Oil pressure light

Oil pressure light is a warning light which indicate either the lubrication system is working properly or not. When the driver switch on, the oil pressure light turn on and when the engine start oil pressure of oil pump switch off the oil pressure switch. Oil pressure switch is fitted on oil filter body or main gallery. If the lubrication system of vehicle is not working properly, lubrication system   light turn on again after engine start. In this case stop the engine and check the lubrication system of vehicle.

Battery charging light

Battery charging light indicates the faults in charging system. when the driver switch on the ignition switch charging light glow and when the engine starts charge light off if indicates that charging system is working properly and if there is faults in charging system in this case charging lingt does not off after the engine start. In this case stop the engine check the fan belt and charging system of vehicle.

Check engine light

A check engine light or malfunction indicator lamp (MIL), is a tell-tale that a computerized engine-management system uses to indicate a malfunction. Found on the instrument panel of most automobiles, it usually bears the legend engine, check engine, service engine soon, maintenance required, and when illuminated, it is typically an amber or red color.

The light generally has two stages: steady (indicating a minor fault) and flashing (indicating a severe fault). When the MIL is lit, the engine control unit stores a fault code related to the malfunction, which can be retrieved—although in many models this requires the use of a scan

tool. This warning light can indicate almost anything from a loose gas cap to a serious knock in the engine.

The Common Problem: Engine Noises

When an unfamiliar noise starts coming from somewhere under the hood, people get scared. They may not know enough about complex engine systems to know if it’s something to worry about or not. Let’s discuss some of the source areas mechanics find to be the most common places for engine noises to originate from

Valve Train Noise

Valve and hydraulic lifter noise has a clicking sound that usually quiets down as you raise the engine RPM’s. A lifter is what opens and closes intake and exhaust valves. These noises can be caused by worn or sticking hydraulic lifters. Sticking lifters in most cases is caused by a varnish build up on the lifter surfaces. They may also be caused by low oil pressure (which would cause a hydraulic lifter to collapse).

Sticking lifter problems can many times be solved by adding a detergent additive to the oil. If this doesn’t do away with the noise, then the worn lifters that continue to make noise would require replacement. This is not an easy or cheap job and will need to be done by a trained auto repair technician.

Timing Chain Noise

Many of the newer engines have overhead camshafts with longer timing chains. A timing chain connects the crankshaft to the camshaft to insure the valves open at the proper time. The slack in these chains is usually kept tight by hydraulic tensioners. The chains ride against a nylon guide (a chain guide) which, in time, begins to wear. At the point where the chain guides are worn beyond the ability of the hydraulic tensioner to take up the slack, the timing chain begins to rattle. This noise is caused by the timing chains becoming so loose that they whip back and forth against the guides and possibly the timing cover.

 

If the oil pressure is correct, replacement of the hydraulic tensioners and chain guides would be required. A mechanic’s stethoscope is a great tool to pinpoint this noise. If the noise is loudest when touching the timing cover with the stethoscope disassembly would be required to confirm and to repair the problem. This is a semi major job for most of these engines and would usually cost in the four digit range.

Detonation, Pre-Ignition (Pinging) Noise

You usually hear this noise when accelerating the vehicle. Most people call this a pinging or rattling sound. This noise is caused by an air/fuel mixture in the engine cylinder being ignited prematurely by the heat of compression as the piston is moving up on the compression stroke. If ignition happens before the piston reaches the top of its stroke, this is called pre-ignition or pre- detonation, which can damage the pistons, valves and connecting rods. They get damaged because the fuel igniting too early produces pressure waves from the fuel’s explosion in the cylinder, which collide with the cylinder as it’s moving up. And that’s also why you hear the pinging and rattling noises.

Some of the causes of this condition are improper fuel octane, engine overheating, improper ignition timing, the EGR valve not functioning properly and problems with the computer or knock sensor. All these conditions can cause the air fuel mixture in the cylinders to ignite before it’s supposed to. This creates multiple flame fronts in the cylinder fighting each other and causing the pinging and rattling noise. Check your owner’s manual to make sure you’re using the right grade of fuel. Or you can switch to a higher grade for a period and see if the noise goes away. If it doesn’t, you’ll want to look at these other possible causes.

 

Connecting Rod Noise

Connecting rod noise is caused by excessive clearance between the crankshaft and the connecting rod bearing surface. This happens when you have low oil pressure causing the bearing to run dry of lubrication, which in turn will damage the bearing and crankshaft surfaces. This can also be caused by poor maintenance practices such as not changing oil at a regular interval. The oil gets dirty and grit can wear the surface of the bearings. The noise you hear is a knock that is heard towards the bottom of the engine. The noise is usually heard when you hold the throttle at a steady RPM. If it sounds like a single knock, you (or your mechanic) can isolate the cylinder by disabling the spark or the fuel injector for each cylinder one at a time. When the noise goes away or gets much quieter, you have found the problem. Problems like this require immediate attention because continued running of the engine in this condition will damage the crankshaft and require a major engine overhaul. The rule of thumb is, once you hear the noise there is a high probability you will need major engine work in the four figure cost range.

Crankshaft Bearing Noise

Crankshaft bearing noise is also caused by low oil pressure which damages the bearing surfaces and could eventually damage the crankshaft itself. This type of noise is usually described as a rumbling or thumping sound deep in the engine when accelerating. If this sound is heard, it is extremely important that the engine not be run again until the oil pan is removed and the crankshaft bearings are inspected. In many cases the engine can be saved if the crankshaft is not damaged. A mechanic will fix the problem by replacing the bearings and solving the oil pressure problem. Bearing shells are what the crankshaft rotates within. If you continue to run the engine with this condition, you will most certainly cause a major engine failure. It is also a high possibility that when you hear the noise it may be too late to save it without removing the engine. This can be an expensive repair in the four figure cost range.

Piston Slap

This noise is caused by excessive clearance between the piston skirt and the cylinder wall, and is usually found on high mileage vehicles. The usual cause of this problem is cracks in the lower piston skirt. The piston skirt is the lower part of the piston which will develop cracks over time due to metal fatigue. The noise sounds like a muffled bell sound or a hollow clatter deep in the engine and is more noticeable when the engine is cold. If the noise goes away when the engine warms up, nothing needs to be done. The clearance is reduced by the expansion of the piston skirt as the engine comes up to temperature, and in many cases the noise goes away completely. If the noise is reduced when the engine temperature rises but does not go away, then replacing

the piston itself would be the most likely remedy. There is really nothing you can do to prevent this problem and, luckily, it’s not as serious a repair job as some of the ones above.

Piston Pin Noise

Piston pin noise is similar to valve train noise. The noise is unique because you will hear a double knocking sound caused by the lack of oil and excessive clearance between the piston pin and the piston. A piston pin attaches the connecting rod to the piston. It is lubricated by oil which is sprayed onto the pin through a hole in the opposing cylinder’s connecting rod.

This condition can only be remedied by replacing the piston pin bushings, possibly even the piston itself, along with solving the oil pressure or lubrication problem. Problems like this are usually a result of worn connecting rod and crankshaft bearings which reduces oil pressure. If you have this problem, it will result in major engine work in the four figure cost range.

Whining Noise

A whining noise when an engine is running is usually an indication of a bearing that is on the verge of failure. This noise will increase as the engine RPMs increase.

Remember, though, that there are multiple places in the engine where bearings are used. Thus, there are several items under the hood that can make this kind of whining sound. The water pump, air conditioner clutch bearing (which will only be heard when the compressor is not engaged), fan belt idler pulleys or belt tensioner, alternator and the power steering pump – these are all possible sources for whining sounds indicating future bearing failure.

Whining from the power steering pump will get louder when turning the steering wheel from side to side and the usual cause is low power steering fluid. The best way to diagnose the other bearing noises is with a mechanic’s stethoscope. Failure to repair any one of the items making a whining sound can result in a vehicle break down. Not only that, but other engine components can be damaged when parts with bearings eventually come apart. So it’s a smart idea to get this kind of problem checked out. Spend a little money now to save a lot of money later.

Why is my car stalling?

So what causes car stalling problems? Car engines quit because of a variety if issues around air flow, fuel or mechanics. Some common reasons for motor vehicle stalls include:

·         An empty gas tank

·         A fuel mixture that isn't rich enough (this is usually the cause of cold stalling and intermittent stalling)

·         A faulty fuel pump, alternator or EGR valve

·         A dead battery

·         A dirty air filter that's preventing good airflow

·         Low fuel pressure (if your car only stalls on inclines this may be the case)

·         Problems with releasing the clutch (manual transmission vehicles only)

·         Coolant sensor reading hot

Ignition related problems such as loss of spark