Masterbuilt XL Propane - Mailbox Mod - Heavy QView - Need Some Help!

Discussion in 'Propane Smokers' started by philh, Mar 10, 2016.

  1. I have had this smoker for several years. I decided to do the mailbox mod to it. We use Todd's AMNTS 6 inch pellet smoking tube. If you have never tried one of these I would highly recommend it.

    I got everything together and decided to give it a trial run. I lite the tube with some Pecan and got it smoking. I closed the mailbox door and was pleasantly surprised to see the smoker filling up with smoke. At this time there is no heat in the smoker. Smoke was coming out of the back vent just fine. This would be great for the times that I would like to cold smoke something with no heat.

    I then turned on the burner in the smoker. That's when the fun started. I lost the draft. Smoke started to pour out of the mailbox. I opened the door to the smoker and the smoke started to come back into the smoker. I closed the door and smoke started coming out of the mailbox again. I found out that if I cracked the door a bit then all was fine. Smoke would then flow fine between the mailbox & the smoker.

    I can live with cracking the door open, but any help would be appreciated on how to fix this problem.

    Here are a few pics..

    Here are a couple of pics showing how I have to crack the door.

    This doesn't seem to lose much heat so I can live with it.

    Here's a few pics of the mailbox mod.

    There is a smoking tube lite in there. The draw is working good with the door to the smoker cracked open.

    As you can see in these 2 pics the smoke is being transferred well.

    Thanks for looking. I did warn you that this was heavy on the QView. lol

    Last edited: Mar 10, 2016
  2. Bringing this back to life...I have the same smoker and about to do the same mailbox mod.  Did you ever find a solution to your airflow issue?  -thanks
  3. Never did find a solution to this problem. I still have to crack the door open when the burner is lit.

    Hopefully someone will chime in here & let us know how to fix this problem.

    Last edited: Apr 20, 2016
  4. solidbob

    solidbob Fire Starter

    Hi, thanks for linking to this in the other post. Do you have any vents for airflow on top/back besides the small vents that were then when you purchased it?

    Looking through that other thread about mods to this smoker, I noticed a lot of people fixed airflow issues by installing a small 2-3" chimney in the top. None of these had the mailbox mod but seems had similar issues with the smoke hanging around in the box and getting stale.

    I have the mailbox mod on my electric MS  and put a 3" vent out the back. I kinda wish I had done the top but it does help with airflow.
  5. I just have the vents in the top back that came with the smoker. I haven't tried to mod a chimney for it. I might need to try that.
  6. daveomak

    daveomak Smoking Guru OTBS Member SMF Premier Member

    The smoker has inadequate air flow....   The burner is heating and expanding the air inside the smoker...   There is NO place for the expanding air to go EXCEPT out the MB mod....  Those smokers are notorious for poor air flow...    Using a step drill, drill holes in the top portion of the walls for ventilation until you get smoke coming out the holes when the burner is operating...

    When smoking, you need bunches of air flow... 
  7. I did this mod a few years ago and it seemed to help the air flow.  I just got the AMNPS tray so I'll be doing the mailbox mod soon.  Hopefully I won't have the problem with smoke going back to the mailbox with the smoke stack mod.

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