BOOM

[OldMayfield]

Tried to heat up my 780Pro to 350F with Pit Boss Mesquite pellets (emptied the bag to top off the hopper - I‘ve had good experience with Pit Boss). Never ignited, but entered Preheat mode anyhow, then stopped with a “Low Temperature” alarm. I could not get past the alarm, shut down and after 15 minute cool down tried again.

Second time it ignited (started smoking) but never entered Preheat mode. Temperature did not change, but continued smoking for several minutes longer than usual - then “Boom!”. The temperature took off, shot past 450F before I shut down and again (and my wife made me fry the burgers).

Post-Morten today: Burnt pellets bits around the outside of the firebox. Singeing of the metal surfaces around the firebox. Charred in the firebox. No pellets within one turn of the auger, then burned ones the next turn or two. Hopper fine, and auger near hopper fine. Pellets a bit dusty, but not too bad.

My guess: burning in the firebox was hindered from the rest of the grill (including the thermocouple) until it “blew” through the hindrance. Pellets? Powder? Fumes? Any ideas?

Also, I think I need a new thermocouple. See photos. Agree?

 

[JamesB]

Tried to heat up my 780Pro to 350F with Pit Boss Mesquite pellets (emptied the bag to top off the hopper - I‘ve had good experience with Pit Boss). Never ignited, but entered Preheat mode anyhow, then stopped with a “Low Temperature” alarm. I could not get past the alarm, shut down and after 15 minute cool down tried again.

Second time it ignited (started smoking) but never entered Preheat mode. Temperature did not change, but continued smoking for several minutes longer than usual - then “Boom!”. The temperature took off, shot past 450F before I shut down and again (and my wife made me fry the burgers).

Post-Morten today: Burnt pellets bits around the outside of the firebox. Singeing of the metal surfaces around the firebox. Charred in the firebox. No pellets within one turn of the auger, then burned ones the next turn or two. Hopper fine, and auger near hopper fine. Pellets a bit dusty, but not too bad.

My guess: burning in the firebox was hindered from the rest of the grill (including the thermocouple) until it “blew” through the hindrance. Pellets? Powder? Fumes? Any ideas?

Also, I think I need a new thermocouple. See photos. Agree?View attachment 5599

Looks like the thermocouple is the problem. The protective cap is gone, and it’s bent. Looks like it got hit with something...top rack maybe.

 

[Slimpicker]

I just bought a spare for grins, they were only $25 2 weeks ago.
I agree with James, you might have bumped that before you started your cook (but would that have really resulted in his experience??)

 

[JamesB]

(but would that have really resulted in his experience??)

I think it’s definitely possible. Who knows what kind of information that thermocouple was sending the controller.
When it failed to light, the controller may have received the info that it was already lit, or it could have been just the opposite, causing the controller to fill the pot with pellets.
I’m wondering if he cleaned the pellets out of the pot, after it failed and shut down the first time. If not, that could explain why he got the overfire the second try.
At any rate, we know that the thermocouple is probably toast.

 

[OldMayfield]

Thanks everybody. I ordered a new thermocouple yesterday. Slim, they’re still $25, and free shipping from Traeger!

 

[OldMayfield]

Success!! Thanks guys. Simple job. The YouTube video for replacing a thermocouple on a D2 WiFire grill is right on, clear and easy. My only advice - have a can of compressed air available to blow clean things that are exposed when the parts are off.

 

[Slimpicker]

Slim, they’re still $25, and free shipping from Traeger!

I got mine in a box right here on my desk... waiting for.... "some day"

Success!! Thanks guys. Simple job. The YouTube video for replacing a thermocouple on a D2 WiFire grill is right on, clear and easy. My only advice - have a can of compressed air available to blow clean things that are exposed when the parts are off.

Awesome THNX Mayfield