Grid Heater Bolt Came Loose

[Conifer]

Figured I'd post this as a warning to everyone. So this just happened to me. I'd been getting a recurring p2609 code for a bit, and after some digging found this in the grid heater. The little piece of the bolt in my hand ended up welding itself on luckily, and didn't fall into the cylinders, but it was only just hanging on. Had it fallen into the engine there would have been some trouble. The bolt I'm pointing at in the picture is the one that came loose. Check your trucks!

 

[DonFitzwater]

GOOD CATCH!!! I'm sure it's something we'll likely never run into again but you never know.

Just a question, what is your starting habit on your truck? Do you cycle the grid heater more than the standard wait time?

 

[TRAMPLINEMAN]

Last weekend I was at TCDiesel and Todd showed me pictures of this same situation of another guys truck. One major difference, his fell into the cylinder and was total devistation.

 

[Conifer]

GOOD CATCH!!! I'm sure it's something we'll likely never run into again but you never know.

Just a question, what is your starting habit on your truck? Do you cycle the grid heater more than the standard wait time?

No, just the normal wait to start, and then it does it's thing. I have the push button start and it will start after the heater cycles. For reference for everyone, here is the picture of the bottom of a normal grid heater, you can see the bolt/nut on the far right that came off on mine.

 

[Conifer]

These are a couple pictures I found online. That bolt on mine that melted is basically the stud that goes from the bottom of the grid heater through it to the top, and attaches to the black piece in the picture I've included here with the grid heater delete. That black piece is what connects to the heavy wire that feeds the grid heater, which connects via a stud that is being pointed at in the 2nd picture I've included here.

Unfortunately to check that bolt, you basically have to remove the whole damn thing, as far as I can tell.

My guess is that it somehow got too much power or shorted itself and melted, but I'm not too sure. As mentioned above, I don't do any abnormal grid heater operation, so I don't know how it could have happened.

 

[JR]

Holy crap! Even scarier that someone else has seen the same thing.

 

[Learjet]

its been reported a few times...I hope Cummins changed something on the 2017 or later.

 

[TCDiesel]

See Picture.

 

[DonFitzwater]

So the hardware is getting hot! Too much current passing through too small of a conductor I suspect.........all it would take is for either of those components to come loose and blammy!

 

[Cummins12V98]

TCDiesel nice full size pic!

 

[seafish]

OP...dam lucky catch!!!
TCD...NICE picture...how MANY of these failures have you seen or heard about other then the two??

My inner armchair engineer is guessing that the repeated expansion and contraction of the fastener from the repeated heat/cool cycles of the grid heater itself is causing the fastener to loosen over time...DEFINETLY kinda of a lame of Cummins to use threaded fasteners in a part whose primary purpose is to go through repeated and fairly extreme heat cycles in its lifespan that also allows for extreme engine failure if the fastener fails!!!

 

[TCDiesel]

2 More ,one at the dealership, the other at CF with picture , unfortunately the guy at CF was over 100K miles, Ram/Cummins up to this point are NO help unless in warranty time frames.

 

[JR]

2 More ,one at the dealership, the other at CF with picture , unfortunately the guy at CF was over 100K miles, Ram/Cummins up to this point are NO help unless in warranty time frames.

Sounds like I need to open up my intake and do an inspection.

 

[Mike Wenrich]

Couple questions. What do you have to do to get to this critter and is there a fix better than either tightening the bolt or replacing it? Maybe JB Weld it???? Or thread locker???

 

[JR]

I've been thinking about this as well. My initial thoughts are the fasteners used are likely bargain bin bolts, low grade carbon steel. Without knowing if this is heat related or current/arc it is difficult to accurately diagnose. Im thinking replacing these bolts with some 304 ss would be a step in the right direction. 304 is rated for something like 1600 degrees F, CONTINUOUS, compare this to your average carbon steel grade 5 fastener of around 450F MAXIMUM, repeated heat cycles only add to the equation.
I wish we knew more about these bolts and exactly what is going on.

 

[jhenderson]

Most likely it’s a case of poor quality control when it comes to torquing the fastener. Loose connections cause high impedance( heat) and arcing, which causes what’s pictured. If it was simply poor fasteners or as mentioned, too small a fastener we’d all have this problem.

 

[JR]

How are these nuts held in place? Similar to a captive nut? In the second picture, first post I see what appears to be a small weld puddle (tack)

 

[jhenderson]

I believe that weld puddle you see is actually melted fastener. Simple torque seems to be the thread locker.