What Causes 6.7 Cummins Grid Heater Failure?

Cummins has a rich history of robust, dependable, and cutting-edge diesel engines, but nobody's perfect. For example, many might remember the killer dowel pin issue, one that stemmed from a tiny metal part prone to coming loose, albeit with devastating effects. 

While thankfully the 6.7 Cummins iteration doesn't suffer from the previously mentioned issue, it has a different malady in the form of a single bolt on the grid heater that can fail, causing potentially thousands in engine damage. Imagine taking the utmost care in maintaining your 6.7-liter Cummins turbo diesel RAM, only for a rogue bolt to snap, tumble into your engine's intake manifold, and eventually arrive at one of your cylinders. In case you're wondering, the eye-watering cost of completely replacing a 6.7-liter Cummins out of warranty is just south of $30,000. 

Fortunately, there are solutions to the problem. These include OEM replacement parts as well as upgrade kits that address the situation. But first, let's talk about why the grid heater's design can cause the bolt to fail.

The bolt in question is found on the grid heater, which is meant to aid the engine when starting in colder temperatures. Research has found that within the first moments of an engine turning over in the cold, a variety of harmful fumes such as nitrogen oxides and carbon monoxide are released due to cold components and fluids, resulting in the combustion chamber failing to burn all the fuel. A grid heater, which isn't the same as an engine block heater, uses heating elements to warm up the air going into the engine. Using energy from the battery, this component can not only help enhance the engine's lifespan but also reduce emissions. 

The design of the 6.7 Cummins Grid Heater places the notorious bolt in a position where it's both under stress from heat and an electrical current. With these two forces routinely acting upon the fastener, it suffers from corrosion, which eats through the metal, eventually detaching the bolt completely from the grid heater.

There are a few options for those with a 6.7 Cummins who don't want to face the consequences of a corroded bolt bouncing around inside their engine. First, you should test whether the bolt is already loose, as the part is accessible from the top of the engine. If you do feel some play regarding the bolt, you have a choice to make.

You can order a replacement OEM Cummins grid heater. However, you could find yourself in a similar situation down the road since Cummins hasn't updated the design. 

Some 6.7 Cummins owners have considered simply removing the grid heater and not replacing it with anything. While you can remove parts or delete a diesel truck, it's generally a bad idea. In this case, owners have cautioned that ripping the part out may cause issues with airflow; and, most importantly, starting the diesel up in the cold will be challenging.

Some parts manufacturers offer grid heater upgrade kits that include things like a new air intake and alternative heating methods that don't include the grid heater or troublesome bolt. These aftermarket kits don't come cheap; they can run nearly $1,000. However, considering the possibility of a potential engine replacement should the grid heater bolt fail, the price of an upgrade kit is a fraction of the cost.