What fuel pressure would you get from a diesel pump? 15 psi - 18 psi in the new engines
How does the diesel pump work and why do we need to time the pump? The pump has to be timed so it delivers fuel at the right time and not for example when the piston is a BDC. The pump runs straight off the crank shaft so as the motor is running more slowly it pumps less fuel and when it is pushed to go faster the pump pumps more fuel to the engine.
How do you time the pump and with what equipment would you use? To time the pump you start by taking of the cam belt then lining up the notches in the sprockets with the marks on the block, once this is gone put the belt back on making sure the marks are still lined up. Now use the DTI gauge to set the motor to specifications. (sometimes you have to take off the pump to get the cam belt off).
What is the purpose of a glow plugs and how do you test the circuit? Glow plugs heat the air so it is hotter than the outside temperature, at this point it has also expanded because of the heat which would make the diesel ignite more effectively as a result of a more compression. You can test the each plug by measuring the resistance there is through each glow plug using a multimeter (if it reads approximately less than 5 ohms the plug is not defective). You can also test it straight from the battery (using jumper leads) if it works the plug will glow like a hot element.
Why do we need an lift pump on diesel engine? to supply/feed the diesel pump with fuel so there is no unnecessary stress on the diesel pump to pull and push fuel.
Why do we need a electronic fuel shut of valve? So that in a emergency there is a much lower chance of an explosion because there is no fuel traveling near exposed sparks etc
What is the knock sensor for and where is it situated? The knock sensor works by simply retarding the timing until the detonation stops. There is a significant decrease in power as it retards it also saves the engine from detonation which will break pistons and burn up head gaskets, The knock sensor is usually on high compression engines e.g. turbo's, performance cars and diesels an is located on the bloch of all cars.
How does the diesel injectors work? The fuel is delivered to the injector at a low pressure (5 -10 psi) by the diesel pump, once there it is pressurised to 2000 - 6000 psi, once the pressure is high enough it sprays into the compression chamber. http://www.youtube.com/watch?v=JgbuE1FT5Ks
Why do you need to bleed a diesel engine after replacing a fuel filter or removing the pump? Because air pockets might occur making it hard to start and could damage your starter motor.
How do you bleed the system? Pump the big primer button before you unscrew the metal fuel lines just a little bit so that the fuel can escape. Turn the engine over but don't start it until you see fuel spray from the base of the lines where the are screwed down.
How does a turbo work? A turbo runs straight from the exhaust which spins
Why do we need a turbo fitted to a diesel engine? Mainly to improve peformance because diesels are such torquie engines you wouldn't get much speed at high revs, more fuel and air adds alot more speed.
What is a supercharger? This is pretty much a air compressor because more fuel and more air = more power they are belt, chain or gear driven so power to the wheels from the throttle is instant.
Whats the difference between a turbo and supercharger? A super charger uses belt or chain driven pulleys to force more air and fuel into the combustion chamber, it also takes horsepower to make horsepower so there is no lag. A turbo charger takes pressure from the exhaust to spin a turbine which compresses and forces more air into the engine. Because a turbo runs off the exhaust is doesn't use any horsepower from the engine to make more, the only down side to a turbo is the lag as it winds up.
Why do we need a after- cooler or inter-cooler fitted to a diesel engine? The air coming from the exhaust is hot so it is ppushed through an intercooler which cools the temp, the turbo then force feeds the engine with more air. Because the air is cold is is more dense so even more oxygen is therefore in the bore getting compressed.
What the difference between in a direct-injection ( DI,) an indirect-injection ( IDI)? D.I has the injector spraying "directly" into the bore so it can be compressed by the piston at TDC resulting in ignition. I.D.I injects the fuel in a mixing/swirl chamber just above the bore with the glow plug which is then compressed.
What is the purpose of an governor? There are hydrolically, pneumatic and mechanical governors all of them do the same job which is to control the engines idol speed and top speed.
What is the difference between a diesel and a common rail diesel? A diesel engine is mechanically timed and has much less pressure in the fuel rail, a common rail diesel engine has very high pressure through the fuel rail and everything is electronically controlled and monitored making it more efficient and more powerful.
http://www.freeengineinfo.com/knock-sensor.htm
http://www.ehow.com/how_5183612_test-glow-plugs.html
www.wikipedia.com
Perrin Robinson
Ricardo Macedo
Very good work, well researched.
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