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GMC Tranny temperature question

Discussion in 'GM Powertrain' started by Hummer, Jul 27, 2012.

  1. Hummer

    Hummer Rockstar

    I have a GMC 2500HD WT Classic Body Style w/ the 6L engine and I love it.

    About two months ago I hit a deer coming home on left front and bent the bumper which was right at $1000.00 to repair. Deer are bad in our rural neighborhood so I decided to get a real bumper and ordered a Boondock bumper and it is really a well built bumper and best protection for a front end/grill/radiator/cooler I have seen. The bumper weighs about 190 lbs being 3/16" thick and is designed for a winch but I will not be installing a winch I don't think.

    When the old bumper was removed there was a rubber membrane from the frame cross member and it went out and connected with old bumper but the new bumper did not lend itself for the membrane to be reattached so we just let it hang down.

    Yesterday was first trip of any length with it and I noted the tranny temp was way up. Normally in last two years even pulling a 31' Airstream Trailer the temp was 165 w/ trailer and 160 without except when I hit a seven mile 5% grade in Virginia and tran temp got to 195 by the top of the mountain and quickly went back to 165 within ten miles which was amazing. The engine temp never moved climbing the mountain ! ! ! !

    So yesterday I went on a 50 mile trip each way and I noticed the tranny temp went to 185 and nothing was in tow. I gave a looksee and there was nothing obstructing air flow to tran temp but the rubber membrane hanging down blocked air flow under the radiator to the bottom of the engine and tranny lines to and from the trans cooler.

    I called my mechanic friend and told him and he said give it a run holding the membrane up parallel with the ground (like factory installation) and I held it up with two small spring loaded clips and I drove it 19 miles and temp never got over 160. Thus the air flow being blocked to lower front of engine appears to be a issue.

    It would seem the logical thing to do would be just remove the membrane all together but my mechanic friend mentioned it was put there for a reason one of which might be to keep air coming into the radiator/tran cooler area only and not be diverted downward.

    Question: Does anyone know for sure the purpose of the rubber membrane and whether issues would develop it it was just removed?

    http://www.goboondock.com/#!customers-rides click through pics till you see a red Dodge pickup with bumper and grill guard which is the design I got. Note the top line of the bumper fits exactly like the factory bumper.
     
  2. aloxdaddy99

    aloxdaddy99 Rockstar 3 Years 1000 Posts

    I am not sure what membrane you are talking about. But, after looking through those pics I don't see where the bumper has anything to do with a reduction of air flow. I also must say thanks. Cause now I have to save up some cash to get one for my truck!!:sign0020:
     
  3. Hummer

    Hummer Rockstar

    I bought bumper through realtruck.com. Do a search for Boondock and it will come up. I talked to the factory guy and he said he only has one dealer on east coast but plenty from Oklahoma to west coast. It comes by truck banded to a pallet and it takes two guys to handle it. I have a good friend who is body/fender type and I got him to ramrod putting it on. They know where all the pop clips are and have the tools to remove them safety. You will need the clip tool that looks like a Y to pop the covers off and the grill. It is about a two hour job for two guys. There are two grades of bumpers 85 and 95 I think it is and I got the heavy one which I think is the 95 with the grill guard added on. I looked at lots of bumpers and only two I could find that use 3/16" steel is Boondock and Road Armor. The Road Armor uses 3" tubing and is like 800.00 higher. They also only make them for trucks not over four years old best I could figure.

    The Boondock is also powder coated a shiney black. Sure is an attention getter. I pull up to an intersection and guys in other trucks are staring at it.

    The rubber membrane/mat is attached to front cross member. You can probably see it from the underside looking up toward lower crankshaft pully. I drove truck all over today and it was quite hot with the membrane clipped up with some little clips that are quite strong. I bought some extra ones at Home Depot today to carry in door pocket should one come off on my upcoming trip.
     
  4. aloxdaddy99

    aloxdaddy99 Rockstar 3 Years 1000 Posts

    it seems like the membrane you are talking about is just a splash guard. Something to help keep water of the engine. I would take it off and see what happens. But, as you said a mech. who can actually look at it said to keep it. That leaves you 2 choices 1. get a second opinion or 2. take it off and see what happens.
    I had a trail ready bumper on my last jeep (pic in album) and loved it. The bumper alone weighed probably close to 200 lbs. I didn't weigh it but it took 2 guys struggling to get it onto the frame horns.I did go with a winch and a set of PIAA 520's.Maybe one day I will replace the front and rear of my current ride. I am not sure what color I would get it in but one day!!! Or should I say some day!
     
  5. Sierraowner5.3

    Sierraowner5.3 Rockstar 3 Years 1000 Posts

    those are some interesting looking bumpers. I will have to keep them in mind.

    Alex
     
  6. Hummer

    Hummer Rockstar

    Apparently the membrane/splash guard is critical. Talked to an A1 tranny guy and he said not to remove membrane but to hold it up like it came from factory.

    I used a couple clips and clamped it up parallel with road and it seems to be THE TRICK.


    I hit the road with it and the temp was about 170 where before it was 165. Also on the Fancy Gap Grade in Virginia last year got to 195 and this year 203 but cooled back down to 170 range within ten miles of the top fo the grade.

    Ran into very heavy rain storm and the 18 wheelers were down to 35 MPH. tranny temp went down to 145 ! ! ! ! ! ! ! Visibility was about fifty yards for spotting a 18 wheeler. Worst rain I have ever pulled the Airstream in and all was fine.
     

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