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Testing & Lost The Gasket

Grandpas Grub
Grandpas Grub Posts: 14,226
edited November -1 in EggHead Forum
Doing some tests today, I lost the gasket again on my medium.

At 24 minutes the medium was at 700° and held for 4 minutes.

@ 31 minutes, thinking it doesn't look like the egg is going to get any hotter and concerned about the gasket I decided to shut everything down.

Closed bottom vent
@ 32 minutes 650°
@ 33 minutes 600° and began to smell something odd. I knew what had happened.
@40 minutes 530°

I opened the dome and you can see the result at below.

I pulled off what I could of the gasket and at about 400° I got the puddy knife and began taking off the adhesive & gasket material.

One positive note, it sure is easy to remove the failed gasket material when the egg is hot, other than the heat present.

It took about 6 to 8 minutes and both dome and base were very clean.

This is the worst melt down I have had.

First was the adhesive failure then at the 4 o'clock position the felt gasket itself began to melt. The last temp read of the felt itself at the same position was 459°. Same position just above the ridge was 405°.

Just below the base ridge same position 397°.
Dome temp was 700° lump 1107° (2 readings left and right of center). Top lump black, just under surface was lava orange.

I could never get an even pull full circle on the dollar bill test. 7 o'clock was very tight almost tore paper. 9 o'clock was weakest pull. Snug at best.

Worst part of failure 4 o'clock. The pull there was 'good'. (not tight but harder than snug - no other way to describe it).

After I cleaned the gasket material off the dome touched base at the 7 o'clock point and had a 1/4" visual gap at the 11 o'clock point. Could easily measure at least 1/8" gap the rest of the way around the dome.

I need to wait until tomorrow to see if the dome will actually sit flat on the base with no gaps.

This medium is a few months old, no idea how long it has been in dealer stock, but the dome was replaced once already.

I am of the oppinion that the adhesive membrand has a temp failure point. If the ceramic/felt goes above that point the adhesive will 'melt' and begin to liquify. When cool it will gain some 'stickyness'.

After seeing this meltdown and reading many posts of folks using MAPP to easily remove the gasket, I feel the 'cure' theory is false.

I tend to think the gasket problems lead more to the fit of the base to dome.

I am also not discounting the ceramics can simply get too hot for the adhesive being used and the felt.

Here are the pictures...

medgasket1.jpg

medgasket2.jpg

medgasket3.jpg

GG

Comments

  • Broc
    Broc Posts: 1,398
    Just wondering --

    Would the foil blocking of the insulation space increase stress on the gasket?

    I'm still using my original gasket -- what's left of them...

    ~ Broc
  • I would imagine that the foil is pliable enough so it does not matter, but I would be concerned with putting something between the fire ring and the egg, or the firebox and the egg. When things get hot they expand, and that may crack the egg.
  • Grandpas Grub
    Grandpas Grub Posts: 14,226
    Broc,

    :edit of post:

    To answer the question. I don't 'think' there was enough heat generation from the foil to the gasket in a direct manner. However, the outside of the egg was much hotter than I remember on non plugged cooks. I remember the outside of the egg being hot. Hot enough to jirk back if touched.

    However, in another post I mentioned, stupidly I touched the side of the egg below the lower band and did get a hurtful burn - no blistering but it hurt for 15 or 20 minutes. I felt a need to put my finger in my mouth to cool it down. Not bad enough to get up and get some aid - it did hurt though.

    :end edit:

    I looked at the Whiz site and the temps he reported at gasket level. My temps, not quality tested and I read outside of the egg rather than inside were much hotter. I can only think the same spots would be even hotter and thus the gasket failure.

    It would be interesting to know the rated fail temp of the adhesive membrane.

    From the posts I recall reading more people have adhesive failure than have actual felt failure.

    From what I see in the photos and what I recall on a previous failure on my large the adhesive gave before the felt melted.

    If you can and have time, sometime, take a piece of type paper about the width of a dollar bill. Check the tightness of your dome against the base. I would be interested to know if there are any weak or loose tug spots. I would be interested to learn the spots at 12, 2, 4, 6, 8, 10 o'clock. (12 o'clock being the hinge spot).

    I am trying to come up with a way to describe the tightness. Possibly a 0 to 5 rating.

    0. being a gap - paper free to move in or out.
    1. somewhat loose - easy tug to move
    2. some tightness - some resistance when pulled
    3. snug - fair amount of resistance
    4. very snug - a big hard to pull
    5. paper close or will tear when pulled.

    When I replaced the gasket on this medium the fit was.

    12 = 3
    2 = 3
    4 = 2
    6 = 3
    8 = 5
    10 = 4

    If you look at the pictures of the failure the bottom the failure will correspond almost exactly to the tug factor.

    Without the gasket the match is horrible, dome inside bands.

    I will check the match when the bands are loose or off.

    I am leaning toward these failures as being a alighment related as much or more than high temp.

    Thanks for your help and ideas, Kent
  • Stanley
    Stanley Posts: 623
    Now I feel bad for encouraging you to further tests. Had my MBGE up to 700° yesterday (overshooting on the way to 650° for a TRex) and my gasket is still fine. I may have missed some previous thread, but did this test come with some gap plugging?
  • Grandpas Grub
    Grandpas Grub Posts: 14,226
    Yes, you are correct. Folks should be very careful when putting anything in the egg that would be rigid and very close to snug inside the egg.

    The metal expansion will cause cracks.

    The foil rope was loose enough rolled to avoid any expansion stress. I would think I could easily compress it 50% to 75% without much problem.

    GG
  • Grandpas Grub
    Grandpas Grub Posts: 14,226
    Hi Stanley,

    Hope your steaks came out great!

    I had full intention of running this test no matter what anyone said. I was feeling pretty 'proud' of this gasket making it through the other tests. 700° was my mental shutdown limit on this test. Frankly I didn't expect the egg to get over 650 or so degrees.

    My concerns were more toward the long time it took to get to a higher temp and secondary the high temp limit.

    I don't think in mentioned it in the original post above, but I stopped the test and closed the vents. I began to smell the gasket burn on the close down at 600° 2 minutes after shutting the lower vent (top vent wide open) - I didn't want residule heat build up in the dome with the ceramic cap on.

    I have a question for you with your 700° yesterday.

    What size egg?
    What brand of lump?
    Was the load all new lump or previous burn?
    Was the egg completely clean?
    How long did the dome read 700°?
    What is the altitude of where you are at?

    Finally, if you can or have the time would you test the fit of your dome to base.

    Use the question I posed to Broc and the measureing spots as well as the tug factor. It should only take a few minutes.

    There is a lot more information I have come up with the tests and will post over the next several days.

    Thanks, Kent
  • Stanley
    Stanley Posts: 623
    Kent,

    My Egg's a Medium. I'm currently burning WGC Weekend Warrior. Previously I was burning BGE brand, and it seemed like I was getting higher temps in shorter times with BGE. I should have done more cleaning than I did. I had a bit more than a half load of lump left from the previous cook - still a good distribution of sizes as the WW I'm using has a high percentage of big stuff to begin with. I stirred it up pretty well and got down to the grate to make sure most of the ash fell through. Poked at the firebox holes to see they weren't plugged. I topped with new lump to mid fire ring. Lit in two places near the back with well-buried Weber cubes. Draft wide open, lid closed with top off. After the cubes burned out I stirred a little to distribute the burning coals. Ran up to 300° dome quickly, then plateaued there for maybe 10-15 minutes. I waved my hat in front of the draft a few times and saw the temp start to rise. It quickly went past my 650° target while I wasn't looking but I caught it before it went past 700° - probably no more than a few minutes at 700°. Closed the draft to 3/4" and DFMT to daisies only and it started going down, so I went to prep my steaks. Checked a few times and closed things down a little more as I was still above 650°. Steaks went on at 650° and I seared 90 sec/side with dome open before I pulled them and closed things down to get to 400°.

    My elevation is 50' above sea level (maybe 60' on my 2nd floor deck :) . I'll try your dome fit test later and let you know, but I'll tell you now my sense is that I am blessed with an extremely well-aligned dome. Never seen any leaking smoke and my (original) gasket looks uniform all around. Doesn't look new, mind you, but not bad.

    BTW, the rib eye was great. Put it back in at 400° with a temp probe and pulled it at 125°. Next time I'll go to 130°, as it was on the rare side of medium rare - still very tasty.
  • Grandpas Grub
    Grandpas Grub Posts: 14,226
    Stanley,

    The rib-eye sounds mighty nice.

    I am wondering about altitude differences and how much that might relate to high temp.

    The majority of this testing has been done on my medium and I am a bit hesitant to use the small as that will change what I am using for a constant in these tests.

    It has been pretty consistant that getting past the 625° mark it is consuming a lot of lump. I will easily end up with about 40% of the lump used after shutting down.

    After the burn and cool down, I press the lump down to get an idea what is left. Usually the level will drop about 1/3 in the fire box. Considering the shape of the fire box, and without measuring, I am think about 40% is being used.

    Back to the high tempeture. Filling lump to the top of the fire ring would most likely produce higher dome tempeture. At this point in time I am not sure if I am going to chance another gasket loss.

    Kent
  • BENTE
    BENTE Posts: 8,337
    i don't even think my "gasket" is still on my small.. it is ok though i usually nly use my small for "grilling" i have slow cooked a few things and my temp held pretty good.. although i only went about three hours with a fatty.. here is a pic of another low and slow armadillo eggs
    2008-5-23002.jpg

    2008-5-23003.jpg

    maybe you can see how little "gasket" i have left :laugh:

    happy eggin

    TB

    Anderson S.C.

    "Life is too short to be diplomatic. A man's friends shouldn't mind what he does or says- and those who are not his friends, well, the hell with them. They don't count."

    Tyrus Raymond Cobb

  • Grandpas Grub
    Grandpas Grub Posts: 14,226
    Thanks bente,

    That gasket looks a little better than my large gasket.

    My large will still hold very low temps so I am not going to worry about it for now and until I get the medium replaced.

    GG
  • BENTE
    BENTE Posts: 8,337
    this is as bad as i have let my large go
    101_0359.jpg

    that is a real old pic i now have the nomex (of course)

    i did try your foil trick. seemed to do well


    although i have never had trouble getting my small up to nuke temps before... if it was giving me any problems i just throw more lump on and leave the dome open a little while longer ;)

    happy eggin

    TB

    Anderson S.C.

    "Life is too short to be diplomatic. A man's friends shouldn't mind what he does or says- and those who are not his friends, well, the hell with them. They don't count."

    Tyrus Raymond Cobb

  • Grandpas Grub
    Grandpas Grub Posts: 14,226
    LOL... Other than that fold at 6 o'clock my large may have yours beat as far as bad goes.

    Mine still cooking great. I have a Nomex ready to install when I get a round to it.

    GG
  • BENTE
    BENTE Posts: 8,337
    just don't streach it... trust me :pinch:

    happy eggin

    TB

    Anderson S.C.

    "Life is too short to be diplomatic. A man's friends shouldn't mind what he does or says- and those who are not his friends, well, the hell with them. They don't count."

    Tyrus Raymond Cobb