Diesel work continued

Why do we need an lift pump on diesel engine?

A diesel pump works by taking in the low pressure fuel and increasing the pressure before being fed top the injectors. The diesel pump needs to be timed in order to deliver fuel to the right injector at the right time. If the timing is incorrect the motor would not have enough fuel to run correctly.

Info from: http://calvinbayley.blogspot.com/2011/06/diesel.html 

 

Image from: http://www.dslautomotive.co.nz/what.htm

Why do we need a electronic fuel shut of valve?

A solenoid valve is an electromechanical valve controlled by an electric current. The electric current runs through a solenoid, which is a wire coil wrapped around a metallic core. A solenoid creates a controlled magnetic field when an electrical current is passed through it. This magnetic field affects the state of the solenoid valve, causing the valve to open or close. Diesel fuel shut-off solenoids transport diesel fuel from a machine's gas tank to its engine. A diesel fuel shut-off solenoid is attached to the machine's main electrical system, which can monitor and detect abnormal temperatures or mechanical malfunctions. Should something go wrong, the electrical current running to the solenoid will be interrupted, causing the solenoid valve to close and shutting off the supply of diesel fuel to the engine.

The Shut off solenoid

The solenoid coil

Info and images from: http://www.ehow.com/how-does_5016171_diesel-fuel-shutoff-solenoids-work.html

The knock sensor:

A knock sensor is screwed into the side of the engine block and allows the engine to run with the ignition timing as far advanced as possible. The computer will continue to advance the timing until the knock sensor detects pinging. At that point the computer retards the ignition timing just enough for the pinging to stop.  

A knock sensor assures that you're getting as much power and fuel economy as is possible from your engine.

Info from: http://wiki.answers.com/Q/What_does_a_knock_sensor_do

 

Image from: http://www.c-speedracing.com/howto/lsvtec/lsvtec.php

How the diesel injector works:

A video found on YouTube on how the diesel injectors work:

Why and How do you bleed the fuel system?

BLEEDING THE FUEL SYSTEM:

It will be necessary to bleed the fuel system to achieve a steady air free flow of fuel

 

BLEEDING PROCEDURE:

Be sure to have some means available to catch or absorb any fuel escaping during the bleeding process so that it will not accumulate in the engine compartment or bilge.

1. Be sure there is a sufficient supply of fuel in the fuel tank.

2. Open the fuel shut-off valve at the tank.

3. Start the electric fuel pump by turning the ignition key to the "ON" position

4. Turn engine over with starter. Crank at 10 second intervals while doing steps 5 and 7.

5. Slowly loosen the air bleed plug on the fuel filter, letting air escape until an air free flow of fuel is evident.

6. At this time, tighten the air bleed plug on the filter.

7. Slowly loosen the air bleed plug on the injector pump, letting air escape until an air free flow of fuel is evident. Units with a self bleed return valve, open for a short period then start engine, as soon as engine runs smooth close valve.

8. At this time, tighten the air bleed plug or knurled knob on the injector pump.

9. The fuel system should now be properly bled and ready for operation.

Refer to starting instructions before attempting to start the engine after bleeding the fuel system.

CAUTION: Excessive cranking with sea cock valve open can cause water accumulation in the muffler and possibly back up into the engine. Drain muffler as needed.

 

FUEL INJECTORS:

Fuel injectors should be removed and taken to a qualified diesel engine repair center to be tested for leakage and spray pattern, if poor engine performance such as loss of power, rough or uneven running, sudden notice of dark exhaust, or engine becomes hard to start.

 

REMOVING INJECTORS:

1. Clean the area around the injectors before removing.

2. Loosen nuts holding fuel lines to injector pump and injector nozzle and remove fuel lines

3. Loosen nuts on return line adapters and remove adapters

4. Loosen injectors and remove injectors.

 

REPLACING INJECTORS:

1. Check to be sure contact surfaces and area around injectors is clean.

2. Replace injectors in the same cylinder from which they were removed.

3. Torque required to properly seat the injectors will be between 43 and 58 ft./lbs.

4. Replace fuel return lines and secure nuts.

5. Replace all fuel lines and secure all nuts.

6. After all injectors, fuel lines and hoses have been replaced and are secured, the fuel system will have to be bled.

Be sure the fuel injection pump has been set at the factory and should need no adjustment. Any apparent problem with the pump should be referred to a qualified diesel mechanic or to a Universal Diesel dealer as advised.

Info from: http://www.marinedieseldirect.com/universal/200157/universal-owners-manual-bleeding-fuel-system.html

How the turbo works:

Turbochargers are a type of forced induction system. They compress the air flowing into the engine. The advantage of compressing the air is that it lets the engine squeeze more air into a cylinder, and more air means that more fuel can be added. Therefore, you get more power from each explosion in each cylinder. In order to achieve this boost, the turbocharger uses the exhaust flow from the engine to spin a turbine, which in turn spins an air pump. The turbine in the turbocharger spins at speeds of up to 150,000 rotations per minute (rpm) -- that's about 30 times faster than most car engines can go. And since it is hooked up to the exhaust, the temperatures in the turbine are also very high.

Info from: http://auto.howstuffworks.com/turbo.htm

A video from YouTube about how turbo chargers work:

Parts of a turbo charger:

Image from: http://www.cubiccapacity.com/auto-tech-speak-turbocharger/

Another video from YouTube showing a turbocharger in action and it’s effect on the engine:

Why do we need a Turbo on a diesel engine?

Most diesels are now turbocharged and some are both turbo charged and supercharged. Because diesels do not have fuel in the cylinder before combustion is initiated, more than one bar (100 kPa) of air can be loaded in the cylinder without preignition. A turbocharged engine can produce significantly more power than a naturally aspirated engine of the same configuration. Turbo charging can improve the fuel economy of diesel engines by recovering waste heat from the exhaust, increasing the excess air factor, and increasing the ratio of engine output to friction losses.

Info from: http://en.wikipedia.org/wiki/Diesel_engine#Supercharging_and_turbocharging

 What is a supercharger?

A supercharger is any device that pressurizes the air intake to above atmospheric pressure. Both superchargers and turbochargers do this. In fact, the term "turbocharger" is a shortened version of "turbo-supercharger," its official name. Superchargers are powered mechanically by belt- or chain-drive from the engine's crankshaft.

A video of a supercharger being wined up: (The supercharger in in the front of the engine)

How much power is too much power?

What do you mean ‘it’s too big’?

Image from: http://socialpathology.blogspot.com/2011/05/supercharger.html

An internal view of a supercharger:

Image from: http://www.redlined.org/images/superchargers/super-charger-13.jpg

What is the difference between a turbo and a super charger?

A supercharger is driven directly from the engine and thus its boost output is directly related to engine speed. A turbocharger is more directly controlled by the pressure of the exhaust gases which, as well as increasing with engine speed, also vary significantly with engine load.

Info from: http://en.wikipedia.org/wiki/Turbodiesel#Turbochargers_v._superchargers_for_diesel_engines

Two photos showing the setup differences between a turbo, and a supercharger:

Images from: http://otomotifashion.com/turbochanger-vs-super-changer/

Why we need an after/inter-cooler on a diesel:

An intercooler is a simply a heat exchanger mounted between the turbo-charger, or super-charger and the inlet side of the engine. Cold air is blown through it to cool down the hot, compressed air inside; this makes it denser and gives maybe another 10% more power.

Info from: http://autorepair.about.com/cs/generalinfo/a/aa102001a_2.htm

What is the difference between direct and in direct diesel injection?

Direct injection:

Direct injection injectors are mounted in the top of the combustion chamber. The problem with these vehicles was the harsh noise they produced. Fuel consumption was about 15 to 20 percent lower than indirect injection diesels, which for some buyers was enough to compensate for the extra noise.

Info from: http://en.wikipedia.org/wiki/Diesel_engine#Direct_injection

Image from: http://www.uiweb.uidaho.edu/bioenergy/Combust_Emisns.shtml

In direct injection:

An indirect injection diesel engine delivers fuel into a chamber off the combustion chamber, called a pre-chamber or ante-chamber, where combustion begins and then spreads into the main combustion chamber, assisted by turbulence created in the chamber. This system allows for a smoother, quieter running engine, and because combustion is assisted by turbulence, injector pressures can be lower, about 100 bar (10 MPa; 1,500 psi), using a single orifice tapered jet injector.

Info from: http://en.wikipedia.org/wiki/Diesel_engine#Indirect_injection

A video showing the IDI principle:

What is the purpose of a governor?

A vital component of all diesel engines is a governor which regulates the idling speed and maximum speed of the engine by controlling the rate of fuel delivery. Unlike Otto-cycle engines, incoming air is not throttled and a diesel engine without a governor cannot have a stable idling speed and can easily over speed, resulting in its destruction.

Info from: http://en.wikipedia.org/wiki/Diesel_engine#Fuel_delivery 

Image from: http://www.tb-training.co.uk/CIsys.htm

hat is the difference between a diesel and a common rail diesel?

In common rail systems, the separate pulsing high pressure fuel line to each cylinder's injector is also eliminated. Instead, a high-pressure pump pressurizing fuel at up to 2,500 bar (250 MPa; 36,000 psi), a "common rail". The common rail is a tube that supplies each computer-controlled injector containing a precision-machined nozzle and a plunger driven by a solenoid or piezoelectric actuator. (similar to a 4 stroke petrol)

Info from: http://en.wikipedia.org/wiki/Diesel_engine#Common_rail_direct_injection

So, here is a common rail diesel engine:

Image from: http://www.swedespeed.com/news/publish/Features/printer_272.html

and here is a normal diesel engine:

Image from: http://gmgenuineparts.wordpress.com/