How fire if no glow plugs?

[JonathanBurk]

My friend asked me this last night and I have no idea. If our trucks have no glow plugs, how does it fire? I'm not sure of the exact details of the diesel engine. I thought it just compresses the air so much that it ignites or some junk like that.



So can someone tell me how, and do Ford & Chevy still use glow plugs?

 

[AggieJustin]

That is correct, this is a compression-ignition engine. The air and fuel are compressed to the point where they ignite. The glow plugs only serve to pre-heat the combustion chamber on a cold start so that the compression will ignite the fuel/air.



On these engines, we use a intake grid heater instead. This heats the air coming through the intake prior to going into the cylinders. Whereas the glow plug heats the air directly in the cylinder.

 

[jwilliams3]

The air is compressed to a point that it is so hot that when a fuel mist is injected into it ignition occurs.



Grid heaters and glow plugs are only to pre-heat air on colder mornings for a more efficient combustion event.

 

[RRoton]

When I was a kid (before most of you were born) I had a model airplane engine that was diesel. It had a glow plug that I had to hook up to a battery to get it started. It was very hard to start, but once it started, it ran great WITHOUT A BATTERY.

 

[67guzzler]

RRoton --



Not sure how far back you were referring to but since I was a kid in the 60's they had nitro/caster oil engines (most common were Cox, Fox, Testors & McCoy) with glow plugs and they also had true diesel model engines without glow plugs at all. True diesel model engines weren't very common back then tho.



The Nitro / Caster oil glow plug engines work the way describe. They still do today.



The true diesel model engines use a variable compression head. You set the compression lower to start so you don't bend the connecting rod or break the crankshaft while cranking. You use Ether along with the diesel fuel to get it to start. After the engine starts, you kick up the compression and drop the ether.



Starting back in the middle 70's Davis Diesel Development sells a kit to adapt a glow plug engine to true diesel.



It's pretty cool stuff.

 

[JasonCzerak]

Alot of people I run across that hasn't a clue about diesels trying to relate "spark plugs to glow plugs". The understanding of the fact that once the motor is running, on a cold day only, you do not need any sort of heat source to maintain an engine speed. This boggles the mind of these people.



Also, the fact that Diesel is rather the oppsite when it comes t o fuel useage also boggles the mind of car people that understand the glow plug idea and nothing furhter with diesel. "black smoke is ok with diesel" doesn't compute, typicaly, that would make a gasser fall apart,

 

[GHanna]

Alot of people I run across that hasn't a clue about diesels trying to relate "spark plugs to glow plugs". The understanding of the fact that once the motor is running, on a cold day only, you do not need any sort of heat source to maintain an engine speed. This boggles the mind of these people.



Also, the fact that Diesel is rather the oppsite when it comes t o fuel useage also boggles the mind of car people that understand the glow plug idea and nothing furhter with diesel. "black smoke is ok with diesel" doesn't compute, typicaly, that would make a gasser fall apart,

Huh???????

 

[JasonCzerak]

Huh???????

I suppose I could of used a few differnet words there. But what I said stands.



Simple version: Most of the people I talk to that do not understand "diesels" think that SparkPlugs are the same thing as GlowPlugs. . They think the glow plugs keep running 100% of the time the motor is running.

 

[Island Dodge]

Jonathan



Glow plugs are used in engines that are indirect injection, which have "pre combustion chambers". Cummins, Cat, Jimmys are direct injection, no pre chambers, no GPs.

 

[67guzzler]

Jonathan



Glow plugs are used in engines that are indirect injection, which have "pre combustion chambers". Cummins, Cat, Jimmys are direct injection, no pre chambers, no GPs.

I never thought about the correlation. Is that an iron clad rule? Don't the VW TDI's have glow plugs?

 

[Turbo Tim 1]

Jonathan



Glow plugs are used in engines that are indirect injection, which have "pre combustion chambers". Cummins, Cat, Jimmys are direct injection, no pre chambers, no GPs.

I think that is wrong, the powerstrokes and duramaxes are direct injection and have glow plugs. Direct injection means the fuel gets squirted into the combustion chamber and not into an intake plenum area.

 

[PToombs]

TT1, Island Dodge is right. A pre combustion chamber is a small insert with a hole that is set in the head, the glow plug and the injector both go into this area. Direct injection goes into the cylinder.

I admit that I don't know what ford and chevy use, never had to work on one, thank goodness!

 

[Turbo Tim 1]

Duramax 6600 6. 6L V-8 (LBZ)



Type: 6. 6L V-8



Displacement (cu in / cc): 403 / 6599



Bore & stroke (in / mm): 4. 06 x 3. 9 / 103 x 99



Block material: cast iron



Cylinder head material: cast aluminum



Valvetrain: OHV



Ignition system: compression, glow plug start aid; low-resistance spark plug wires



Fuel delivery: direct injection diesel with high pressure common rail



This info was taken from Here The last two items say glow plugs and direct injection, they may have some type of pre combustion chambers but they are direct injection and have glow plugs, so the statement of glow plugs are only in indirect injection is wrong I think.

 

[67guzzler]

You're straight Turbo Tim 1. I think it's a misnomer that DI engines don't have glow plugs. They MIGHT not but I don't think they necessarily CAN'T.



That link also said "low-resistance spark plug wires" -- WTF?