Paul Alton MBA

Cummins 6.7 diesels have something called a killer grid heater bolt. They do not use glow plugs to preheat the combustion chambers like traditional diesel engines. They have a grid heater in the air supply duct to preheat the air going to the engine. It is activated when the ambient air is cold. At forty below it is activated for a long time. If the control relay feeding it power gets stuck it is activated for a very long time. This can overheat the bolt holding the electrical connection to the grid heater. The bolt can overheat enough that it melts and the nut on the end falls off and ends up in the engine. Brace for an incoming $20,000+ repair bill.

There are some fixes out there that totally remove the grid heater. They are not cheap. BD Diesel came up with a fix that eliminates the bolt. It doesn’t eliminate other downstream weak links that could happen, but at $300 bucks it’s worth a consideration. I bought it online from an X ad. It arrived this week. Their videos said three hours for a complete install. Another video mentioned one hour but that was for modifying the grid heater bus bar once you had it in your sooty, fat hands but that was not getting it out and getting to turning the key to start the engine to test the installation.

I started on Thursday afternoon and finished on Saturday afternoon. Mostly. The engine ran fine on Saturday with no leaks. It wasn’t until the following Tuesday that I had the clip back on the bypass pipe and found where the “extra” bolt had come from (a cable bracket on side of EGR valve) that I could reinstall the cover around the dipstick. I think an experienced diesel mechanic who had done the job before and had the right wrenches could do the job in the three hours quoted. I probably took about twelve hours actual hands on wrenches time.

It is a big job for an amateur in his driveway. I kind of knew that going in but grew in appreciation of the size of the job as I stumbled through the step by step. As I told Juanita before and during, “if I get in over my head it may mean sending it to a shop behind a tow truck but I’m willing to accept that risk of cost and humiliation.”

Here’s some observations, occurrences and sources of delay caused by my ignorance.

The instructions are very detailed. They mention wrench and socket sizes needed for most steps. They do assume you know what you are doing and what engine components are named. I lost a lot of time figuring out how most electrical connectors came apart. For the most part they are not where you can examine them closely and they do not willingly give up their secrets by braille. I paused to watch several YouTube videos about connectors. The helped but not totally. The connector on the fuel rail defeated me. I managed to get the fuel rail swung out of the way still electrically attached to the truck. The last injector fitting at the engine also proved a challenge. It took a bit of ingenuity to at least loosen it at the block. A makeshift extension using a bolt in the box end of a combination wench helped. Thanks, YouTube. Cutting a slot in another ¾ inch box end wrench to make a flare nut wrench also helped. Once loosened I didn’t dare completely remove the fitting nut. There is no conceivable way I could reassemble that. I just swung the loosened tubing out of the way after it was disconnected at the fuel rail and loose at the block.

I learned on YouTube that a ¾” wrench is as good as a 19 mm wrench for the injector fuel line fittings. That was good to know. I have only one 19mm wrench, but two ¾” combination wrenches. Now, three if you count the one I just bought to replace the out cut into a flare nut wrench.

Stupid things.

I dropped the seal washer for the EGR cross over pipe. Twice. Finding it the second time was easier.

There are two seal type washers on the banjo bolt which I assume is a return fuel line from the fuel rail. The instructions warned about not letting it drop. I got the one easily, but the other was in there tightly. Until I loosened something else. Then it wasn’t. Gravity works. Couldn’t find it. I bought another at Napa in town Saturday morning when I went to town to buy some nuts and bolts for the homemade wrench extension. The RAM dealer was closed for the long weekend.

The clamp holding the EGR cross over pipe to the engine sprung open when I removed the bolt holding it to the engine. That’s going to be a joy to put back, I thought. It was. If you are a masochist. The radiator hose is in the way. You can’t see what you are doing.  The bolt is too short to make contact with the threads with the clamp sprung open. A much longer bolt would be too long and contact the plastic valve cover. I tried sneaking up on it several ways. All failures. I parked the problem on Sunday and Monday. There would be no stores open for the July 1^st holiday. It could wait. By Tuesday I had decided to go to town and buy a slightly longer bolt and grind it to a point to align things. It was either that or remove the radiator hose to get access. Ugh.

Setting the timer for thirty minutes for one last try I aligned the clamp with the hole with a small screwdriver and then compressed the two legs of the clamp with a small pair of needle nosed vise grips. Success. Now onto the remaining issue. The “extra” bolt. Another ten minutes hanging into the engine compartment with a bright flashlight revealed its home. Remove the dipstick. Go to install the cover. Loosen EGR cross over pipe flange clamp so it’s not in the way of the cover. Retighten. Install cover. Reinsert dipstick.

Job done.