Diesel engines ignite the air/fuel mixture with heat generated by friction and compression, while gasoline engines use the heat caused by a spark from a spark plug. That's why diesel engines are referred to as compression ignition engines and not as spark ignition. Diesel engines generally have a compression ratio of 17:1 to 22:1, which aids in the heating up of the mixture (gasoline engines are around 8:1 to 10:1). High-performance diesel engines use a lowered compression ratio, often around 12:1, which isn't high enough to heat the air/fuel up and ignite. That's why high-performance engines typically use ether or another starting aid to get the engine running.
From the factory, starting aids are employed to preheat the air or combustion chamber to help the engine start when the weather is cold. These are needed because the piston doesn't generate enough heat when everything is extremely cold. The Cummins 5.9L, found in '89-to-present Dodge trucks, uses an air heater, while the Ford Power Stroke (6.0L and 7.3L) and Chevrolet Duramax engines use glow plugs that are located in the cylinder head to heat the combustion chamber.
Over time, glow plugs wear out and stop working. If you notice that the truck is very hard to start when cold, and/or produces white smoke when starting and idling until it is warm, you might have a glow-plug problem. We're not saying that's what it is (so no letters saying I changed my glow plugs and it still didn't start), but these are typical signs of glow plugs going bad. There are other components in the system, like on the 7.3L Power Strokes, that use a relay on top of the engine that is prone to failure.
But nevertheless, glow plugs do wear out and BorgWarner Turbo and Emissions Systems has recently released a newly designed glow plug that is better than a straight replacement. These plugs are designed to heat up faster to aid in start-up, while reducing start-up emissions. We went ahead and contacted BorgWarner Turbo and Emissions Systems to get a set of these, as we knew of an '03 Ford 6.0L Power Stroke that was having some issues on cold start-up. Once we received the plugs, we took the truck over to our friends at Diesel Dynamics in Joshua, Texas, to walk us through the process.
Product Profile
BorgWarner Turbo and Emissions Systems
www.borgwarnerglowplugs.com
Diesel Dynamics
817/558-3673
The first step is to remove...
The first step is to remove the intake. Be sure to unplug the vacuum gauge and map sensor before taking it off.
We went ahead and removed...
We went ahead and removed the coolant reservoir bottle (also known as a degas bottle), so it was easier to photograph. Taking off the two bolts that hold the bottle is necessary, but it isn't necessary to detach the coolant lines.
The next step is to unplug...
The next step is to unplug the glow-plug buss wiring harness.
Once the glow-plug buss has...
Once the glow-plug buss has been unplugged, the entire bar (or assembly) can be gently pried away from the head and removed.
With the bar removed, the...
With the bar removed, the glow plugs are exposed. Using deep sockets and short extension, the glow plugs are loosened.
A magnet is used to pull the...
A magnet is used to pull the glow plugs out of the hole.
Once the old plug is removed,...
Once the old plug is removed, the new glow plug is slid into place.
With the glow plugs in place,...
With the glow plugs in place, use a deep socket and handtighten the plug. Then use a ratchet and tighten to the appropriate torque spec. (Check your manual for manufacturer recommendations).
After all four plugs are installed,...
After all four plugs are installed, the glow-plug buss bar is reinstalled and the wiring is reconnected.
Next, the coolant reservoir...
Next, the coolant reservoir bottle is reinstalled (or in your case, bolted back in) and the intake is reassembled.
On the passenger side, the...
On the passenger side, the intercooler tubing is removed.
Next, the Glow Plug Control...
Next, the Glow Plug Control Module (GPCM) is unbolted from the valve cover and laid off to the side.
For automatics, the transmission...
For automatics, the transmission dipstick needs to be loosened and pushed off to the side.
Once again, the glow-plug...
Once again, the glow-plug buss was unplugged and the bar was removed. Then the glow plugs were loosened with a deep socket and extension (except for the back two plugs where an extension is too long).
With a magnet, the old glow...
With a magnet, the old glow plugs are removed and the new glow plugs are reinstalled by hand.
With the glow plugs installed...
With the glow plugs installed and tight, the glow-plug buss bar is reinstalled and connected.
Next, the transmission dipstick...
Next, the transmission dipstick is put back in place and the GPCM and intercooler are reinstalled.