New Masterbuilt 40 problems

Discussion in 'Masterbuilt Electric Smoker (MES) Owners' started by hellac, Aug 9, 2014.

  1. Hi all, just bought a Masterbuilt electric 40 smoker from Sams for $299. It has the console on the top front and the side air vent and is 1200 watt. It has the windowed front. I guess this makes it a Gen 2. I have never been more disappointed.

    My first try was 1 rack baby back ribs. First problem was trying to keep the temp at 225 - there is a 30 to 50 degee variance between my Maverick ET-732 and the console on the Masterbuilt. I also put in an inside oven thermometer that agrees with the Maverick. Then the element would shut down and not come back on for quite a while even if temp was well below the setting on the console. So I tried to run my AMPs inside and could not keep it lit – side vent open full and chip tray pulled out halfway, still wouldn't keep lit. Nothing was dripping on it, tried 4 times it just keep going out.

    I did a ham on day 2 and had similar problems. I was setting the temp at 275 just to try and get it to 225. It in a sheltered spot out of the wind and elements – covered porch. Did I just get a dud?

    Going to call Masterbuilt on Monday – but I am seriously wondering if I shouldn't just box it up and take it back to Sams, and trust me that is something I am not looking forward to - what a pain in the butt.
  2. bearcarver

    bearcarver Smoking Guru OTBS Member

    Sounds pretty typical of Gen #2 MES.

    I would tell them about the 275* setting getting you 225*, and the inaccuracies, and tell them you want your money back, or take it back to Sams for your money back. Then I'd find a Gen #1 MES 40, and get a Great smoker. No matter what they agree to replace, you will never be happy until you get a Gen #1. I'm sorry, but that's the facts----IMHO.

    Don't bother to tell them about your AMNPS not working in it----That will make them happy.

    Last edited: Aug 9, 2014
  3. Can you still buy a new Gen 1?
  4. moses

    moses Meat Mopper

    I have two Gen 1's. One is still brand new in the box and the other is smoking a chuck roast as I type this. I use the cold smoke generator with mine and couldn't be happier.
  5. bearcarver

    bearcarver Smoking Guru OTBS Member

    Here's one-----Make sure to order "Top control/Window" and 40". Not "Front Controller".

    Last edited: Aug 9, 2014
  6. Which cold smoke generator do you use?
  7. bearcarver

    bearcarver Smoking Guru OTBS Member

    Not sure what Moses uses, but I use my AMNS with sawdust for smokes with smoker temps under 200*.

    Then I use my AMNPS with pellets for any smoking over 200* smoker temps.

    You can actually use the AMNPS for either of those temps.

  8. moses

    moses Meat Mopper

    I use the masterbuilt cold smoke generator. You can get them at Bass Pro
  9. From an earlier posting I made.  Measured observations on a Gen II MES 40 (windowless)

    Observations from a geek:

    Test conditions:

    MES 40 "windowless" second generation, model 20070613 available at Lowes for about $279.00 before discounts.

    The unit has already been "smoked in" and used about 4 times since new.

    Test temperature the unit is set for is 225 F.

    Outside temperature is 78 F (early Arizona morning with cloud coverage).

    It has the smaller chip tray, and chip loader from the factory.

    No chips in tray, heating element only.

    No liquids in water tray, wanting to see the unit's inherent temperature characteristics without other "stabilizing" factors (such as water or large hunks of meat).

    Chip tray and loader fully inserted.

    The "second probe" mention below is actually the built in meat probe, plus a chefmate remote probe both near the middle of the unit, set slightly left of center.

    Both probes have been boil calibrated, and read within 2 degrees during calibration and this test event (once you allow for variations in display refresh rates).

    The "button" sensor, which is read by the circuit board to determine when the heating unit is switched on and off is:

    1. located on the same side, and near the heating element.

    2. is bolted to the rear bulkhead.


    1a. on all heating cycles (except the initial heating cycle), it gets up to your set temperature faster than a second probe which is set on one of the middle racks.  This results the heating element switching off before the second mid-rack probe reaching the "set temperature" by about 6 degrees.

    2a. on the initial heating cycle, the thermal mass of the back bulkhead actually lowers the "button" sensor by several degrees (relative to the second probe), which causes an initial overshoot of temperature.  I experienced about a 30 degree initial overshoot of internal temperature due to this characteristic. 


    Initial heat cycle, second probe temperatures hit 255, before the button probe registered 225 and switched off the heating element.

    Temperature dipped to 189-192 on the second probe, before the temperature dipped below 225 on the button probe (bulkhead thermal mass), and switched on the heating element.

    On subsequent cycles, the button sensor hit 225 (and switched off the heating element) when the second probes were at 216; with the element "off" it was still radiating heat and the second probes eventually reached 219. Statistical "average" second probe temperature observed, after two hours, was 205.5 degrees (against a set point of 225).


    On the initial heating cycle, second probe temperature phase leads button probe significantly (due to bulkhead thermal mass, which is conducted into the button sensor).

    On subsequent cycles, the proximity of the button probe to the heating element, and the heated bulkhead causes the temperature phase to lead the second probes "slightly".

    Suggested engineering change:

    Move the button sensor up about 10 inches (and center it from left to right), provide better thermal insulations from the bulkhead, so it reads actual free-air temperature more accurately.

    Devil's advocate:

    Exaggerated temperature swings encourage the heating element to stay on longer, which helps increase the peak temperature seen by the chip holder.  This encourages more complete combustion of the chips.  The large swings also allow for the chips to start smoking at a lower "set" temperature.  The large temperature swings may very well be an intentional design feature.

    For those who are using products like the AMNPS, the large swings are not a benefit.  The typical swing temperature seen, after the unit had been running over 2 hours, was roughly 27 to 30 degrees.  In the grand scheme of things, not bad, but not great. Adding meat and water will improve the stability, but the high to low swing range will likely remain similar, as will the average cabinet free air temperature. More data is needed with a loaded cabinet to be sure.

    Testing Sub note:

    After four hours of testing, the MES's meat probe started reading 20 degrees higher than actual.  Could be a bad crimp in the probe. 

    Opening the front door for ten seconds (dropped chefmate second probe temperature to 170), only caused a 3 degree overshoot (228 vs. 225 set temperature), upon recovery; quite good
    Last edited: Aug 13, 2014
  10. bearcarver

    bearcarver Smoking Guru OTBS Member


    Interesting test results.

    You didn't do a side to side test.

    I tested an MES 40 Gen #2 last year, only I tested Left, Center, and right at different temp settings.

    My conclusion was it is hotter on the right side than the left, due mostly to the slanted drip plate in the bottom which is higher on the right, which traps the heat from the heating element on the right side. Then the heat seeps around the front & back of the top end of that slanted drip plate, causing the right side to get more heat than the left side.

    Removing the water pan from the Drip plate helped slightly, as some of the heat that becomes trapped under the right side of the drip plate manages to rise up through the water pan hole.

    Therefore I found the biggest cause of the uneven heat in the MES 40 Gen #2 is that slanted Drip Plate. This is totally different than the MES 40 Gen #1.

  11. I read your data BearCarver, It was very informative.  This test was to derive other factors as well.

    Another factor on my MES40, is the heating element is on the right.  You get secondary heat radiated from the hot shroud assembly around the heating element. It is the classic battle between radiant heat, vs convective heat flowing from the heating element on the right, and the vent on the left.  Very tricky to balance.  I expected there to be left-right imbalance in heat because of this, so I was shooting for center of thermal mass temperature for the second probe (shifted slightly left, to reduce radiant heat factors).  This test as about looking at heating element switch on/off (hysteresis) points vs thermal mass dampening factors. 
  12. Thanks guys!! As always you all are a great help. 

    When I called the Masterbuilt they had no Gen 1's in stock (hmmm that says something right there). Anyway they sent me a new console and now it works as intended - moves right up to temp and stays fairly close.  So going to cook a couple things this week and see how it goes.  A couple guys told me they love their Gen 2's. I still have a little over two weeks to take it back to Sam's - so going to check it out thoroughly. I will keep you updated.

    Thanks again - you guy's really do come through with the help.
  13. bearcarver

    bearcarver Smoking Guru OTBS Member

    Not all, but most guys who like their Gen #2 haven't had them long. They haven't put anything like 8 Chix Thighs on a shelf, and had to juggle them around because the ones on the right are 20* IT higher than the ones on the left. Hopefully they'll notice it before they eat the underdone pieces. 

    They also have air flow problems in the Gen #2, which makes it very hard to keep an AMNPS going, and since you can't get consistent smoke from the built in smoke generator in an electric smoker that's another problem.

    I'm actually glad that some Gen #2 owners love their smokers, because that means they shouldn't need help.

    I try to get everyone to get the Gen #1 instead of the Gen #2 for selfish reasons. I help everyone I can, and I hate when Gen #2 owners have problems, and there's very little I can tell them to help.

  14. will75

    will75 Fire Starter

    Not to necro. but has yours always worked since then? Even with new digital displays.. none of my gen 40's  (side vent) seem to heat properly. Maybe it's egghead time
  15. inkjunkie

    inkjunkie Master of the Pit

    The reason I went with a 40" GenI was based solely on info I read from Bearcarver

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