why do they have glow plugs ???
#1
12-19-2010, 02:16 PM
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#2
12-19-2010, 02:30 PM
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#3
12-19-2010, 03:20 PM
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I've worked on a lot of marine diesels and regular truck and farm diesels and almost all of them have some type of starting aid. The thing with marine diesels is they are rarely exposed to the elements so they usually aren't in much need of glow plugs. But most of them do have starting aid devices like propane or ether injection at least. John Deere is big on that junk too. My new holland has a small glow plug in the intake and a small orifice on a fuel line that wraps up over the engine, holding several cc's of fuel. When I push the button fuel starts to drip then when the glow plug gets hot enough it lights the fuel in the intake. It's a pretty worthless system but kinda neat.
I think another reason you won't see glow plugs on farm equipment is how many farm tractors have you seen with good batteries? How many farmers do you know who swear by that can of ether? It's a recipe for disaster.
One big opposed piston diesel I worked on had intake heaters, glow plugs, in each intake port. That thing would dump nearly a half gallon of diesel on each one and light if we had to use it. That giant two stroke firing off with the heaters on was a sight to see. I'm glad we didn't have to use them very often.
I think another reason you won't see glow plugs on farm equipment is how many farm tractors have you seen with good batteries? How many farmers do you know who swear by that can of ether? It's a recipe for disaster.
One big opposed piston diesel I worked on had intake heaters, glow plugs, in each intake port. That thing would dump nearly a half gallon of diesel on each one and light if we had to use it. That giant two stroke firing off with the heaters on was a sight to see. I'm glad we didn't have to use them very often.
#4
12-19-2010, 10:30 PM
Consider outside air temps overnight.
Around here that has been about 0 lately.
If I go out in the morning with my truck not plugged in, the engine is about 0 degrees.
So when I turn it on and start cranking the engine without glow plugs, the air temp in the cylinder has one compression stroke to go from 0 to about 500 degrees for the fuel to auto ignite.
Yes, if I sit there and crank on it, the cylinder temps do start to come up, but it is still drawing in 0 degree air.
Heat the glow plugs and put some heat in the cylinder, now it is much easier to reach 500 degrees so the engine will fire.
The after glow, after the engine starts, helps reduce the unburned fuel white smoke while the engine is cold.
Glow plugs extend the starter life by reducing cranking times and reduce air pollution by reducing white unburned fuel smoke.
They also eliminate the need for starting fluid, which there is nothing wrong with if used properly, but can do engine damage if you use to much.
Cracked rings and blown head gaskets and broken rods are the most likely things to be damaged from to much ether at once.
Raise the hood, a little spray of ether, run inside and crank the engine, it fires and stops.
Back out and another little spray of ether, run back and start the engine again, it stalls again.
So the next time out, the spray gets bigger, run back in and the engine starts and revs up to 1500 RPM, but still stalls from lack of heat when it dies back down to idle.
So the next time, the spray gets bigger and when the engine fires it goes to 3500 RPM or higher.
Plus during this whole episode, white unburned fuel smoke is going everywhere with the smell of raw fuel.
Now you and everything the smoke settles on smells like diesel fuel.
Not exactly the ideal way to start a cold engine AND keep the neighbors happy.
Around here that has been about 0 lately.
If I go out in the morning with my truck not plugged in, the engine is about 0 degrees.
So when I turn it on and start cranking the engine without glow plugs, the air temp in the cylinder has one compression stroke to go from 0 to about 500 degrees for the fuel to auto ignite.
Yes, if I sit there and crank on it, the cylinder temps do start to come up, but it is still drawing in 0 degree air.
Heat the glow plugs and put some heat in the cylinder, now it is much easier to reach 500 degrees so the engine will fire.
The after glow, after the engine starts, helps reduce the unburned fuel white smoke while the engine is cold.
Glow plugs extend the starter life by reducing cranking times and reduce air pollution by reducing white unburned fuel smoke.
They also eliminate the need for starting fluid, which there is nothing wrong with if used properly, but can do engine damage if you use to much.
Cracked rings and blown head gaskets and broken rods are the most likely things to be damaged from to much ether at once.
Raise the hood, a little spray of ether, run inside and crank the engine, it fires and stops.
Back out and another little spray of ether, run back and start the engine again, it stalls again.
So the next time out, the spray gets bigger, run back in and the engine starts and revs up to 1500 RPM, but still stalls from lack of heat when it dies back down to idle.
So the next time, the spray gets bigger and when the engine fires it goes to 3500 RPM or higher.
Plus during this whole episode, white unburned fuel smoke is going everywhere with the smell of raw fuel.
Now you and everything the smoke settles on smells like diesel fuel.
Not exactly the ideal way to start a cold engine AND keep the neighbors happy.
#6
12-22-2010, 07:37 PM
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Emissions. It will come to your neighborhood, too soon.
For an example, on some gas engines, you have an intake hose that draws warm air from around the exhaust. Also, a butterfly valve that closes off the exhaust until the engine is warm.
Just read up on what the "new" diesels do for emissions. That is a real eye opener. DPF / urea fluid...
The times, they are a changing. Hang onto your old stuff until you are ready to leap into the future...
"Unfortunately, the 7.3 failed to meet stricter emission requirements and was therefore replaced early in 2003 by the 6.0L Power Stroke. The 7.3 is largely responsible for making the Power Stroke name legendary"
http://www.internationalpowerstroke.com/73psd.html
Here in Kali, diesels from '98 up now have to be "smogged".
For an example, on some gas engines, you have an intake hose that draws warm air from around the exhaust. Also, a butterfly valve that closes off the exhaust until the engine is warm.
Just read up on what the "new" diesels do for emissions. That is a real eye opener. DPF / urea fluid...
The times, they are a changing. Hang onto your old stuff until you are ready to leap into the future...
"Unfortunately, the 7.3 failed to meet stricter emission requirements and was therefore replaced early in 2003 by the 6.0L Power Stroke. The 7.3 is largely responsible for making the Power Stroke name legendary"
http://www.internationalpowerstroke.com/73psd.html
Here in Kali, diesels from '98 up now have to be "smogged".