Diesel engines are notorious for their dislike of cold weather. When temperatures drop, fluids thicken like molasses, and batteries lose power, making it a challenge to start your truck in the winter. Modern pickups have made significant progress in overcoming cold starts, but they still have their limits. To push these limits, a cold chamber in Southern California was built, and a Cummins diesel Ram was frozen inside to see how it would perform at -40 degrees.
The test was conducted with a 2024 Ram 2500 HD in peak condition. New Interstate AGM batteries were installed under the hood, and the 6.7-liter engine's fluids were replaced with fresh Amsoil products, including the brand's Signature Series 5W-40 oil. Winter diesel was used in combination with an Amsoil additive to prevent gelling. The fuel-water separator was also replaced before testing.
Turbodiesel expert Gale Banks introduced the test by listing four major factors in diesel engine start procedures: ambient temperature, coolant temperature, heat of compression, and manifold air temperature. While some factors are uncontrollable, block heaters and intake air heaters can augment the second and fourth factors.
View Price on AmazonTo demonstrate the significant difference block heaters make, Banks tested the truck with and without one. The results show that without a block heater at -20 degrees Fahrenheit, the coolant temperature matches the outside air, making it much harder for the engine to start and reach optimal operating temperature. The engine could only crank at 82 rpm during this test, resulting in a 46.9% loss in piston speed, which diesel engines rely on to start.
When a block heater was used, it warmed the coolant temperature to 32 degrees Fahrenheit, despite the same -20 degree ambient temperature. This significantly reduces wear on the engine, as internal cylinder temperatures can exceed 300 degrees on startup. If the coolant in the water jacket surrounding the cylinder is warmer, the temperature difference isn't as great, resulting in a happier engine for longer.
The tests also showed that even at -30 degrees Fahrenheit, the block heater helped boost coolant temperature to 20 degrees. The truck achieved 89 cranking rpm with heat from a 1,500-watt, dual-element Monster Ram intake. However, when temperatures dropped to -40 degrees, the truck completely failed to start, with a cranking voltage of just 6.4 volts. The batteries couldn't provide enough power to keep the ECU awake.
These tests highlight the importance of hardware in extreme cold weather conditions. Block heaters should be a no-brainer for diesel truck owners in cold-weather states, and heated intake air matters as well. Cummins installed factory grid heaters on pickups like the 2024 model used in this test, although many have suffered from a faulty bolt that melts and finds its way into the engine.
Source: thedrive.com
