engine mounts on 1999 gmc sierra 1500 4x4 with a 4.8l

Discussion in 'General Chevy & GM Tech Questions' started by 4by44ever, Jul 28, 2013.

  1. 4by44ever

    4by44ever New Member

    can anyone tell me if this is normal?
    On the left side(driverside) you have the engine mount bolted down with 3 bolts to another mount ,this other mount has only one bolt put true it? im thinking "If" there should be 2 bolts ,this is why my transmission blew out it's inputshaft.
    It's a 1999 gmc sierra 1500 4x4 with a 4.8l
    thanks in advance

  2. 4by44ever

    4by44ever New Member

    please guys,help me out here.

    99'HEARTBEAT MODERATOR Staff Member 5+ Years ROTM Winner 1000 Posts Platinum Contributor

    The Diagram, is for a 1999" GMC Sierra 1/2 Ton 4WD....Engine & Transmission Mounting-V8, (LR4/4.8V, LM7/5.3T).....its the Driver-side Engine Mounts, and to your Question...."this other mount has only one bolt"....and the diagram its only showing 1-Bolt...Number #6 for that Engine Mount.


    Last edited: Aug 8, 2013
  4. 4by44ever

    4by44ever New Member

    i got the same manual with that picture,but in this diagram the bolt is in the top hole and mine is in the bottom hole,and a diagram from the right side(witch should have 2 bolts on it) is nowhere to be found;
    I would still really appreciate it if anybody could go and see if they have one or two bolts.
    I just keep wondering
  5. RayVoy

    RayVoy Epic Member 5+ Years 5000 Posts

    The question is, I guess, do you have a hole for the 2nd bolt to go into. I know there is a hole in the bracket, but is there a matching hole in the frame.

    I say, no hole, no bolt needed.

    [FONT=Verdana, Arial, Tahoma, Calibri, Geneva, sans-serif]I'm going to say no. The transmission should be securely bolted to the rear of the engine block, they should act as one sold assembly.

    Even if the motor mount broke, the transmission should stay securely fastened to the rear of the engine.

    The torque converter should be bolted to the flex plate and the transmission input shaft should go into the torque converter. If everything is tight, the movement of the engine should not hurt the input shaft[/FONT]
  6. 4by44ever

    4by44ever New Member

    I can follow your thinking on the trans,probebly it is just old age,after 180000 miles something has to break.
    But the bolt,the thing is that there are holes for 2 bolts in the chassis and enginemount-mount?(i don't now an other name for it)and on the back of each hole there is a solid(welded i guess) nut.On the above diagram it is nr 4, these are welded down and there are 2,not one like on the diagram.
    For the moment i have a self-made bolt in the second hole and nut(out of a peace of screw-thread-bar,one size to big and treathed down to the exact size of the welded solid nut). i did not drive the car ,won't be able for the next 3 weeks or so.i really wan't to be sure in advance,i don't wanna find out along the way.
    Everything is there for 2 bolts except for the bolt,with the second bolt instaled the engine lifts about 1/4",so it makes some difference.
    Please anybody that can just go and check,i guess anybody with a 1999 to 2005 V8 gmc sierra or silverado.
    If you are ever in Begium i will get you a platter of real BELGIAN fries and a nice cold bear.

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