Although the 6.7L Cummins engine has been popular over the last two decades, some issues have come to light. A few ideas may come to mind, such as emissions equipment failures and turbocharger/actuator failures, but one that has stuck out lately is a hardware issue in the grid heater system on the intake plenum of the engine.
Although it may not seem like much, this inexpensive hardware can cause a costly repair if not given the attention it needs. From 2007.5 to 2024 6.7L Cummins engines, (2500, 3500,4 500, and 5500 models) a bolt in the stock grid heater can melt and/or break and fall into a cylinder and cause catastrophic damage. Once it breaks, this heater bolt can fall into the engine and destroy a piston, tear up valves, trash the cylinder head, or all of the above.
What Is The Grid Heater Bolt Issue?
The grid heater, the intake air heater, warms incoming air for easier cold-weather starts. In this system, a grid heater plate is bolted to the intake manifold and secured with the bolts. The problem is the material of these bolts. Over time, they can loosen, shear, or break due to many heat cycles, the engine’s vibrations, or simply corrosion.
The bolts are subjected to high temperatures and cooling cycles causing constant expansion and contraction. Plus, the diesel engine’s inherent vibrations put more stress on the bolts. With all of this going on, simple corrosion can be just enough to finish it off.
Signs Of Grid Heater Bolt Failure
The obvious way you could tell if there was a problem with this was if you’d encountered said engine damage. The engine would make a lot of rattling and grinding noises as it chewed up this material, but the idea is to catch this beforehand. There is a power terminal on the outside of the engine near the fuel rail that can be “tested”.
This “wiggle test” will quickly let you know if this bolt is loose. For the wiggle test, gently grasp the power terminal on the outside of the intake plenum secured by a 10mm bolt. Try and move it back and forth. After a wiggle on this terminal, if the terminal moves at all, it indicates the bolt may be loose and requires immediate attention and you should not drive the truck. If you need to drive in an emergency you could but know the risk. It could be on the last thread or the last thin piece of material waiting to drop. However, what if this terminal is tight? Good to go?
No. This is more of a “when” instead of an “if” issue. This needs to be addressed immediately. Luckily for you, there is an aftermarket solution out there that completely eliminates the problem. BD Diesel’s “Killer Grid Heater Upgrade Kit” comes with everything needed to replace more than just the failing bolt.
The Aftermarket Solution That Saves You $$$
The BD Diesel Killer Grid Heater Upgrade Kit is the ultimate solution for addressing the notorious grid heater bolt failure in 6.7L Cummins engines. The kit eliminates the problematic grid heater bolt entirely, replacing it with a more reliable and robust design. Unlike other options, it retains the grid heater’s ability to warm intake air, ensuring reliable cold starts—especially important for trucks operating in colder climates.
Purpose-built to resolve this major design flaw, BD’s kit eliminates the weak grid heater terminal stud and addresses the fastener located between the heating elements. The issue arises when 200 amps pass through the small bolt and nut inside the intake, causing them to deteriorate, arc, and eventually break off. Left unfixed, it could be costly.
The updated kit now resolves the melting fastener problem by directly connecting the busbar to the heating element, eliminating a critical failure point. Additional features include self-locking threads in the lower busbar to maintain consistent clamping force, the specialty tools necessary for easy installation, and new hardware and gaskets to complete.
How Long Does This Job Take?
You may be asking, “How long will a job like this take?” This is a simple installation that can be done with basic tools. The only special tools required are included in its kit and should take around three hours in total. Once you access the grid heater plate, it is a straightforward process, but getting to that area is what accumulates so much time.
Accessing The Grid Heater
To reach the grid heater, you’ll need to begin by disconnecting the vehicle’s batteries. With the power off, proceed to disconnect or remove components such as the EGR valve, crossover pipe, and various sensors. The intake horn must then be lifted off, followed by the disconnection of the fuel lines and the fuel rail.
Disassembly, Modification (if applicable), and Reassembly
Once the grid heater is removed, it will need to be disassembled. If you have a 2007-2012 model, you’ll need to perform a specific modification to the heater as outlined in the installation instructions. After cleaning, reassemble the grid heater using the new components provided in the BD Diesel kit.
How To Address These Failures?
What do you do if it already happened? First and foremost, we’re sorry. We hope that the damage was contained and it isn’t as bad as we’ve heard it could be. However, if you’ve done your “wiggle test” and it’s loose but hasn’t broken, you need to address it immediately and do so. If it has fallen in, the best thing you can do is to tear into it and inspect it or get it to a mechanic who can. Without running the engine, of course.
If you suspect it has failed while driving, shut the engine off. Disassemble the intake manifold and retrieve any loose bolts or fragments before restarting the engine. If damage is found, a full tear-down to inspect the top end of the engine may be required. Some mechanics have access to a scope that can snake into the plenum to inspect the areas internally to see any visible damage.
Whether you’ve gotten lucky and found no problems and collected fragments or had to do a full repair with top-end parts, etc., pick up a BD Killer Grid Heater Upgrade Kit and make sure this never happens again.
Add This To Your Preventative Maintenance Routine
Regular maintenance is essential for keeping your diesel truck running reliably, and checking the grid heater bolt should be part of every owner’s routine. Preventative maintenance isn’t just about oil changes or filter replacements—it’s about catching potential problems early. By proactively addressing the grid heater bolt issue, you’re protecting your engine’s long-term performance and reliability.
Upgrading to BD Diesel’s Killer Grid Heater Upgrade Kit ensures you permanently resolve this problem and eliminate the risk altogether. Adding this check to your routine maintenance schedule is a small step that could save you thousands in repairs and keep your truck on the road where it belongs.
Final Thoughts
To wrap it up, the grid heater bolt issue in 6.7L Cummins engines is not something to take lightly. What may seem like a minor hardware flaw can quickly turn into catastrophic engine damage if left unchecked.
Thankfully, with BD Diesel’s Killer Grid Heater Upgrade Kit, there’s a proven, long-term solution that not only eliminates the failing bolt but also strengthens the entire system for reliable performance. Whether you’re driving through harsh winters or simply looking to prevent costly repairs, this kit delivers peace of mind.
Taking the time to address this issue now—before a failure occurs—can save you thousands in repairs and downtime. With straightforward installation and all the necessary components included, it’s an upgrade that every 6.7L Cummins owner should consider. You’ll not only resolve the weak points in the stock design but also ensure emissions compliance and reliable cold-weather starting.
Don’t wait for that loose bolt to turn into a disaster. Be proactive, grab the BD Killer Grid Heater Upgrade Kit, and protect your investment for the long haul. Whether you’re performing the installation yourself or having a trusted mechanic handle it, this upgrade is a no-brainer for keeping your Cummins running strong and dependable for years to come.
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