Exploding thermometer grommet?


 
M

MTyskow

New member
Has anyone experienced this with their thermometer grommet?

I bought a used 18” WSM and it came with no thermometer grommet and some tin foil and mesh taped over the thermometer hole. I took that off and installed the grommet from my 14” WSM. That did fine for the first couple cooks but today, a couple hours after I took my ribs off, I noticed the grommet was gone, sitting in a pile of dust below the smoker...what happened??690D772A-2950-4344-B928-AD4A8AC4E07F.jpeg
 

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I'm confused. You say the grommet was "sitting in a pile of dust below the smoker" but it's not shown in the photo. Did you pick it up before taking the photo OR was the grommet destroyed and the "dust" is the grommet?

I'm also confused about how the grommet came off of the probe wire. I assume the wire was passed through one of the grommet holes. How did it come off the wire and land on the ground? Did the grommet melt?

I assume that white flame-like mark is also the result of this?

I would guess there was some kind of explosion. Maybe a backdraft fire...you finished cooking, closed the vents, some grease caught fire, there was restricted airflow, a lack of oxygen, then maybe the grommet breached, allowing air into the cooker, then an explosion popping out the grommet.

This thread from 2007 discusses a WSM where the lid blew off two hours into a rib cook. The water pan was found down in the charcoal and the conjecture was that the pan fell, water quickly turned into steam, and the pressure blew the lid off. You don't say anything about water or the pan, but it could be a steam explosion.
 
Sorry, I should’ve said that the grommet turned into a pile of dust below the smoker. There were a few larger chunks that made it obvious what it was, but that picture shows what was left of the grommet.

I did close the vents after I finished cooking but I’ve done this many many times on my 14” without any issue. There was no water in the water pan.
 
So the grommet basically burned up. I'll bet that white flame pattern on the outside is silicone. Your probe wire looks a little janky, like it didn't fare too well, either.

I'm guessing a grease fire consumed the grommet. Any signs of a fire in the empty water pan? Since this was a used cooker, was it really greased up inside?
 
Hmm I didn’t look at the water pan specifically, but everything looked normal inside of the smoker. I’ll have to check it out in the morning.

The smoker actually had very little grease inside of it. The person I bought it from was selling it because of the trouble they had with it...I figured because it wasn’t well seasoned. To your point, though, the foil-wrapped water pan had some grease in it from a brisket that I recently smoked.

I know that silicone can withstand pretty high temps. By the time I noticed the missing grommet, the built in thermometer was only reading around 250-300 degrees. Seems strange to me that the silicone would’ve caught on fire...but then again, I wouldn’t normally expect the smoker to be 250+ a couple hours after closing the vents.
 
Thanks for the help, you must be right. Looks like most of the grease in the water pan did burn off. Since the grommet came from my old WSM 14, it was probably the greasiest thing in there...makes sense that it would’ve caught fire. It was just something crazy that I’ve never seen before!
 
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