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GMG Jim Bowie Help

post #1 of 16
Thread Starter 
Hey guys
I picked up a new Jim Bowie a couple of weeks ago and have been having issues with temp control. Primarily what is said on the control panel vs what is going on under the hood. I set my temp to 225 degrees and wait for it to get up to temp but the external thermometer reads 350+ I have also used a backup thermometer which gives me similar readings as well as the meat probe on the unit. I called GMG and they sent me a new control panel but I still have the same issue. Can anyone think why my temps would be so off like this. I have everything to the best of my knowledge setup correct. Also this unit has the stainless drip pans. Any help or suggestions would be greatly appreciated.
post #2 of 16

I have a JB and found that the key to temp control is adjusting the heat deflectors. Each machine is a little different and it took me the best part of a day to tune it. Once tuned it is an awesome machine. Won lots of ribbons and money with it. A true set it and leave it machine.

post #3 of 16
Thread Starter 
The unit I got was one of the newer units with the stainless steel box and trays it did not come with side heat deflectors
Edited by gmoney13 - 2/26/16 at 12:30pm
post #4 of 16

The heat deflectors go under the drip pan and disperse the heat. They are a must to regulate the heat from sude to side. Without them you will have one side hotter than the other side.

post #5 of 16
Quote:
Originally Posted by gw1947 View Post
 

The heat deflectors go under the drip pan and disperse the heat. They are a must to regulate the heat from sude to side. Without them you will have one side hotter than the other side.

 

With them you will have one side hotter than the other.

post #6 of 16

I have tried the JB without the deflectors and very simply put the heat is way hotter on one side. Explain how you use it without deflectors.

post #7 of 16
Quote:
Originally Posted by gw1947 View Post

I have tried the JB without the deflectors and very simply put the heat is way hotter on one side. Explain how you use it without deflectors.

I didn't say I did. I was being facetious in my response because even using said deflectors I've seen temperature variances of nearly triple digits from one side of the grill to the other on a Daniel Boone WiFi model. While I don't doubt it would be worse w/o the deflectors I have a hard time imagining just how much worse it could get.
post #8 of 16
We have had our Jim Bowie for 2 weeks and 4 cooks on it with similar issues. GMG just sent me the SS deflector and drip/searing pan as ours had the old non-adjustable steel parts even though it was new and from their authorized dealer. Our issue though is that it appears their controller is showing a much higher pit temperature than we are getting at the grate. Cooking times are much longer than on our old trager. I will be installing the new SS parts in a couple weeks to see if that helps but I am already suspecting we have a controller issue. Will update this post if I make any progress.
post #9 of 16

I have heard that the DB is a little more fickle. My JB is within 10 degrees of the controler (higher) and about 10 from side to side.

post #10 of 16
Is your grill a wifi unit? The new 6.0 firmware has a temp compensating feature. Unfortunately I couldn't try it out. My control panel won't except the update. GMG is sending me a new control panel with the 6.0 uploaded on it.
post #11 of 16

I do want to state that I have a 3 yr old JB (without wifi).  I too had the same temp issues when I first got mine.  I had a Maverick ET-732 and a a few cheap temp probes from Target.  First I tested the probes in boiling water and ice water to validate that they were accurate to 212F and 32 F respectively.  

 

Next, using potatoes as my stands, I put the probes across the back side of the grate and set the JB to 225.  After being at 225F for 20 mins I recorded the temps and moved the potatoes to the middle and repeated the process.  The same was done again with the probes at the front.  It took me about 2 weeks of nearly daily playing with the deflectors before the temps were finally dialed in.  

 

The final solution was to place both deflectors in the default location and plug all holes on the top, leaving only the bottom open.  (see rough sketch below for location)

 

 

After this, my temp is +/- 10 degrees from side to side, and +/-15 degrees front to back.  Now, I personally face that the pit runs hotter than controller, but this more of environmental issues based on the weather on the day of the smoke.   On my last overnight smoke, the pit was dead on with the controller but as we approached the high of 75F that day, the pit did become about 30 degrees hotter than the controller (sun was hitting the pit directly).  

 

These findings are what worked for me.  Your mileage may vary. 

post #12 of 16
Our Jim Bowie has the new SS heat deflector and drip pan. I will try to remember to get pictures and post them when we get back up there.
post #13 of 16
Made some mods to our 2 week old Jim Bowie last night

It was getting late so these pictures are dark

First was installing the new installation blanket. We put one on our old trager it really helped stabilize the temp swings especially when the lid was opened and closed. The GMG blanket is good but unlike the trager cover doesn't wrap all the way around. The sides are held in place with magnets that work good but the front is held in place when the handle is removed and reinstalled over the blanket. That part works well but the corners turn up as there are no magnets so I will try to hold them down with a bead of RTV silicone.


Side views. The round spots in the blanket are the magnets.


Even though we bought this new from an authorized GMG dealer 2 weeks ago it was last years model. I talked to GMG customer service and they sent me the new SS drip pan and SS heat deflector no charge. Great customer service! The old steel drip pan is on the right in the top picture and the new 2 piece SS pans are center and left in picture. The holes can be lined up so more heat gets through from the fire box to help when you want to sear. Don't know yet how well it works. The 2nd picture is the old 3 piece heat deflector which didn't seem to work well imho.

Here is the new 1 piece SS heat deflector. It is big, can be centered in the bbq and fits very well. All of the SS parts are heavy gauge.


Here is everything put back together.
I didn't get a good picture but I also filled around the burn pot with lava rock and topped that with half thickness fire brick. We did that to our trager a long time ago and it definetly helped with heat retention, and recovery.
I still have smoke leaking out of the lid in a couple places so will use the old RTV gasket fix for that. It was late, we were hungery and I might have possibly had a visit from my old friend mr. Jack Daniels and a cigar so the results of my cook are not too detailed.
Threw some hamburger patties on after reassembly. After the pellets started smoking I turned it up to hi and I would say it was slower coming up to temp because of the additional mass that needed to heat up. However the fire chamber temp and the grill temp read within 20-30 deg of each other when before they were off by about 80 deg. Also when the burgers went on they sizzled which they didn't do the last time we tried cooking them. I am ordering a tempaque (spelling?)so that will help me better monitor pit, grill and food temps. My hope is it will better help me understand the temp variations in the GMG. I am concerned that the controller isn't working properly but I want some solid data before I call customer service.
I hope this helps some of you other GMG owners or those considering purchasing one. Please ask any questions if I missed something. And if you know of other mods I would appreciate hearing about them.
post #14 of 16
And I must also mention this is the first time I have ever successfully posted pictures on any forum. Still can't believe it worked:)
post #15 of 16

North Idaho,

 

On the New 1-piece Stainless Steel Heat Shield, turn it over and check the Centerline of the Inverted V against the Centerline of the FirePot.  The Locator Notches on the original 1-piece SS Heat Shields were off a bit, making the Chimney Side about 100* hotter.  Some newer heat shields have 2 sets of notches to move the heat shield.

 

Be sure you move the heat shield more towards the Chimney Side when you do the notches.  I had to Dremel out 7/8"

 

The DB had the same issue with the New Heat Shield.

 

Let me know how it comes out, you can contact me at don.g.godke@gmail.com or contact me on Facebook at Don Godke's Downdraft

post #16 of 16
Dgodke thanks for the tip. Our one piece SS deflector does have 2 notches and I did move it towards the chimney as far as could only because I wanted it centered in the bbq. Your explanation makes a lot of sense so my next step is to set up 2 probes on my Igrill at each end of the grate and start recording temps. Will post results when completed. Thanks again!
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