Ram Trades Cummins Grid Heater For Glow Plugs

Since 2007, Cummins-powered Ram Heavy Duty trucks have relied on a grid heater system for cold starts, unlike their competitors, which have long used glow plugs. That changes for 2025, as Ram and Cummins have officially switched to glow plugs in their newest version of the turbodiesel 6.7-liter Cummins I6 engine. While many owners who’ve dealt with catastrophic engine failures due to grid heater bolt failures may see this as a reliability move, Ram insists it was all about improving efficiency and performance.

Why The Switch? – 

Grid heater failures have been a hot topic in truck forums for years. A broken or melted grid heater bolt could enter the engine, causing severe damage to pistons, cylinder heads, and intake systems. While this isn’t an issue for every engine, the risk has been enough to prompt many owners to replace their grid heaters with aftermarket solutions like the Banks Power Monster-Ram intake. Despite this history, Ram says the change wasn’t driven by reliability concerns.

Doug Killian, Ram’s Chief Vehicle Synthesis Manager, explained the real reason behind the move: engine redesign. “This was really us with Cummins, but [we agreed] it’s time to get to glow plugs,” Killian said. “And the start time, like in cold weather, just the reliability, it’s almost instant start. It’s down to three seconds versus 30-plus seconds before.”

An Engine Overhaul Brings Glow Plugs – 

The change was part of a larger redesign of the Cummins engine layout. One major adjustment was relocating the diesel oxidation catalyst closer to the turbocharger for a cleaner burn. Additionally, the engine’s old cast-in intake manifold was replaced with a bolt-on design, allowing for better airflow and efficiency.

Killian emphasized that the glow plug adoption wasn’t a reaction to failures but rather an advancement in technology. “It’s been around for decades, and the grid heater was also working fine for startup, but you had to wait,” he said. “Glow plugs—it was time. It was time to get there.”

When asked if there were other motivations for the switch, Killian reaffirmed, “No, not really. The glow plugs kind of came along for the ride.”

What It Means for Owners – 

For 2025 Ram Heavy Duty truck owners, this means easier, faster cold starts—especially in freezing temperatures—without the long wait times associated with grid heaters. It also means fewer concerns about potential grid heater failures leading to costly engine repairs.

However, for owners of 2007.5-2024 Cummins-powered Ram trucks, the problem still lingers. Since grid heater bolt failures typically occur after the 5-year/60,000-mile powertrain warranty expires, affected owners are often left covering repair costs themselves. And because the issue isn’t a safety concern, the National Highway Traffic Safety Administration (NHTSA) is unlikely to push for a recall.

Source: The Drive