As you are aware, diesel engines do not have spark plugs. That is because diesel fuel ignites differently than regular gas does. If you have a diesel engine, you have glow plugs to help start the motor. The glow plugs are best when you are cold starting your vehicle. Since Duramax is a diesel engine, there will be glow plugs inside warming the The tips dont break off either and make a mess out of the top of the piston. Glow plugs are better because the put the heat where its most important. Though either psd or cummins are tough to get started below -30. At that temp nothing beats a fire starter log. "Im voting for Dukakis". To make starting a 4000 series tractor easier in cold weather put the range selector in gear and turn the key to the start position and hold it there for 5 seconds or so. The glow plugs only come on when the key is in the start position and the safety interlock will keep the engine from cranking. You could use the PTO switch too. Unique shell design for heat transfer. gas-tight. High shear torque. High resistance to deformation and security of the heating coils. NGK glow plugs. heat-resistant metal There are three main groups: NGK glow plugs help your diesel engine get off to a fast and reliable start. Highest performance while meeting emission regulations. Pre-Power Stroke Diesel (7.3L IDI & 6.9L) - glow plug problems on 6.9 - I'm new to the forums and need some help. I've read everything but still in the dark a bit. I have a 1987 f-250 with 6.9 diesel and it has 220,000 miles on it. It has the later version controller and relay on the rear of the intake. As noted by others, the Yanmar engines in the 3X20 tractors have an intake air heater and the John Deere engines in the 4X20s have glow plugs. In my opinion the Yanmar engines start easier in cold weather (without the block heater) than the Deere engines (3 vs. 4 cylinders also help). With a block heater, both seem to start equally well. Glow plugs warm the combustion chamber and the atomized fuel. Up until tier 4 emissions most off road Cummins engines had no grid heaters and still started at below zero temps. This is also the case with some folks who’ve deleted their grid heaters. They still start at below zero temps. Try that with a glow plug equipped engine. The most common sign of damaged glow plugs is a difficult start. Without properly functioning glow plugs, the combustion chamber may not reach the proper temperature to ignite the gasoline and start the engine in cold temperatures. Glow plugs should be checked if there are no problems with the gasoline or the battery. 2. Misfiring of the engine The glow plugs act as heating elements to preheat the air in the combustion chambers, making the vehicle easier to start. What is a Glow Plug? Gas-powered engines use spark plugs to ignite the air-fuel mixture inside the combustion chambers. On the other hand, Diesel engines rely on the heat from the compression of air to ignite fuel. It starts smoking a little bit out of the tailpipe. So the glow plug is programmed to come on as we go down the road and help maintain that cylinder temperature so we get a clean-burning engine. So that’s what glow plugs done have done. It is they’ve tied that to emission control. IqzXG.