VERY basic question--glow plugs, diesel TUTOR - PeachParts Mercedes-Benz Forum

JBG · #1 01-23-2008, 11:44 AM

1. What exactly is the function of glow plugs?

2. Since I have about 1,000,000 more questions like this about my 300 TD, where's the best place to turn? Are there any diesel tutorials? Stuff like: how does the starter/alternator/battery interplay? What exactly is going on in my engine, and what are the different parts that make that happen? What is "spooling" in relation to the turbo? How does my radiator work, where does the coolant go? What are the different functions of a transmission, how does it relate to the engine and other components?

etc. etc. etc. etc. etc.

Sorry for being such a noob. If there really IS a guide to answer all these questions, I'd be VERY interested.

vstech · #2 01-23-2008, 11:54 AM

if you have any auto parts store near you, you may want to pick up a haynes manual. about 10.00 they have them for the 123 vehicles. very little information specific to the wagon, but there is some information to get you going on the automotive world. These cars are very simple to work on, and they are really just like any other automatic equipped vehicle. if you have a library, you can look at just about any automotive instruction manual, and you will understand all the basics of automotive workings. the MB diesel is a bit different, in that it does not have a spark distributer or plugs, but aside from that your basic questions should be answered.

kerry · #3 01-23-2008, 11:57 AM

Question #1 is easy. Question #2 is too complicated to answer on the forum. I'd say a basic book on internal combustion engines and the operation of various systems in an automobile would be the best place to turn for #2

Since diesel are compression ignition engines, they rely on heat to burn the fuel. (Unlike gasoline engines which require the continual firing of spark plugs to ignite the fuel) When the engine is cold, there is not enough heat to ignite the fuel. The glowplug heats up to provide for ignition until the engine provides enough of its own heat. After the initial ignition by the heat of the glowplug, engine heat is adequate to ignite the fuel and glow plugs are not required any more, except perhaps to smooth out the running of the engine for the first minute or so.

dannym · #4 01-23-2008, 12:52 PM

The internet is amazing in all the information that can be had at the click of a button!

http://www.google.com/search?hl=en&q=how+do+diesel+engines+work

Danny

vstech · #5 01-23-2008, 12:58 PM

ya, that will tell how the engine works, but not how the battery relates to the starter, or any of the other questions he posed... to ask all the questions he had of google would take quite a while, plus he may not know what questions to ask. the haynes manual is perfect for him, and the library would be a free way to get general automotive knowledge.
it's surely possible to ask google general automotive questions... just tedious.

Number_Cruncher · #6 01-23-2008, 01:02 PM

>>The internet is amazing in all the information that can be had at the click of a button!

True, but then quite a lot of that info is either just plain wrong, or not representing the full picture. Many of the popular sites get it wrong, and I wouldn't trust them myself. I do agree that the internet is a good place to begin, but any serious work should take you to a decent textbook.

For engines, as a good thorough text, I would suggest Internal Combustion Engine Fundamentals by Heywood.

For more general vehicle information, the series of books by Heisler (sp?) is really excellent.

Phil · #7 01-23-2008, 01:23 PM

If you read some of this and don't get bogged down with all the tech stuff it has some good info. Some where on that site is an animation showing a diesel running that helps to understand it.

http://hyperphysics.phy-astr.gsu.edu/hbase/thermo/diesel.html

A lot of the stuff on this site is over my head but it is fun to look around at whats there. I have pick up some interesting info just snooping there.

JBG · #8 01-23-2008, 03:48 PM

Thanks bros. I will follow up with those sites and perhaps do some research at the local library.

I have the Haynes manual and have found it helpful for the basics such as how to check transmission fluid, do a proper oil change (gotta thank diesel giant for that one as well), where everything is under the hood, etc. Now that I feel pretty OK with where things are, I'm curious to know what they do, how everything interrelates, and all that. The next layer under the surface.

Thanks again,

79300sdtd · #9 01-23-2008, 03:55 PM

i always enjoy http://www.howstuffworks.com/

networkboy · #10 01-23-2008, 04:38 PM

strictly speaking the diesel process relies on compression to ignite the fuel...
heat makes it easier though.

-nB

Diesel911 · #11 01-23-2008, 05:51 PM

If you like to read printed material do not forget most Libraries have books on how diesel engines work and Main Libraries ofte have Haynes/Chilton and other type manuals that you can look at.

TripWagner · #12 01-23-2008, 06:24 PM

Wikipedia has LOADS of info on origin, structure, function and uses of Herr Rudolf's engine. Great pics too!!!

tankdriver · #13 01-23-2008, 08:08 PM

I second the howstuffworks.com site. Great source.

To answer #1, the glow plugs provide heat to help with combusting diesel fuel on start up.

For #2, I can take the time to give you nearly useless basic info. Howstuffworks covers all of that stuff in easy to understand detail. The battery provides power to the starter, which turns the crankshaft at startup. The alternator uses engine power (once it's running) to recharge the battery, which also provides the power for all electrical components. What goes on in your engine is a series of explosions used to rotate the crankshaft which in turn eventually rotates the wheels on the car. Combustion is of diesel fuel, which is injected through a valve at the top of the combustion chamber where it mixes with air. A piston comes up the chamber, driven by the crankshaft, and the pressure of compressing the air heats it enough to blow up the diesel fuel. That shoves the piston back down, casing the crankshaft to rotate. Then another valve opens at the top of the combustion chamber and the dregs of the explosion leave. A turbo is a turbine that takes these dregs, spins, and shoves air back into the combustion chamber to be blown up the next time the piston comes up. It compresses the air, providing more air for the same space in the combustion chamber. Spooling refers to the time it takes the dregs to spin the turbine. Your radiator works by pumping coolant through a pump into the engine to absorb heat generated by the combustion. It goes from the engine to a place where it provides the heat/defrost for the cabin, then back to the radiator where it passes behind aluminum fins which help cool the coolant. The transmission takes the rotation of the crankshaft and through different sized gears, controls the speed of the rotation.

There's a whole lot of detail that makes a lot of that inaccurate, but it's the general idea.