The Glow Plug
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Joined: Apr 2006
Posts: 312
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From: Florida, USA
2017 Rolls Royce Wraith, 1999 CLK Cabriolet, 2023 Genesis G90
The Glow Plug
Hello, everyone:
I was stopped at a light last night next to an old 300 D, and listening to its clackity-clack, it made me recall when one of my cousins drove an Oldsmobile Cutlass diesel about 20 years ago. We fondly called it "el camión," which in Spanish means "the truck," because of the sound of the old diesel engine. I distinctly remember the yellow "Glow Plug" light on the dashboard, which had to be allowed to go out before the engine could be safely started, and that got me thinking. What is it about today's diesels that lets the driver just start it up and go? I know it still must be allowed to properly warm up, but that's much different to sitting there waiting for a light to go out. Any thoughts?
I was stopped at a light last night next to an old 300 D, and listening to its clackity-clack, it made me recall when one of my cousins drove an Oldsmobile Cutlass diesel about 20 years ago. We fondly called it "el camión," which in Spanish means "the truck," because of the sound of the old diesel engine. I distinctly remember the yellow "Glow Plug" light on the dashboard, which had to be allowed to go out before the engine could be safely started, and that got me thinking. What is it about today's diesels that lets the driver just start it up and go? I know it still must be allowed to properly warm up, but that's much different to sitting there waiting for a light to go out. Any thoughts?
MBWorld Fanatic!
Joined: Feb 2004
Posts: 5,143
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From: South Orange County, CA
4 wheels
Common Rail Direct Injection. Diesel is injected into the cylinder at 25,000 PSI so it literally combusts on its own at that pressure. That is why you don't have glow plugs. 
I think MBZ invented this technology.
I think MBZ invented this technology.
Senior Member
Joined: Dec 2006
Posts: 405
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From: Scottsdale, AZ
2007 GL320 CDI, 2001 TJ Rockcrawler, 2005 Scoobie STI
The new generation glow plugs just reach starting temperature much faster than the old ones. If you leave it parked outside overnight in a cold snowy environment, you will notice that it takes a bit longer for the glow light to turn off. (3 seconds instead of 1 second)
My GL has the Keyless Go system, so when I press the start button, it waits for the glowplugs to warm up before the engine actually turns over.
MBWorld Fanatic!
Joined: May 2007
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From: Scottsdale, AZ
2004 RX330, 2008 Scion xB, 2001 Honda Insight Hybrid, 2010 Toyot Prius v ATP
(Just kidding.)
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