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How to replace motor mounts on 4WD I6 TrailBlazer, the (relatively) painless way

Discussion in 'Article Submissions' started by Uri79, Feb 27, 2014.

  1. Uri79

    Uri79 Member

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    Hi everyone,

    Recently I needed to change both motor mounts on my 2007 TrailBlazer 4WD/I6, and having done some reading on this I realized this was not a straightforward process.

    After collecting as much info as I could I went ahead to do the job.
    With some trial and error I believe that I've found a way to do it that makes the process easier, so I'm sharing it here in hope that it would assist others who decide to tackle this work.

    I elected to completely remove the brackets that are attached to the frame rails, through which the lower bolt of the motor mount goes.
    This was much easier than I thought it would be, and it makes removal and installation of the motor mount itself straightforward.

    Improvement with the new motor mounts was absolutely amazing - much smoother and quieter now!
    I've used genuine GM parts, having read that non-OEM mounts are not as well designed for this engine.

    I also took some photos of the critical steps. It took me around 4.5 hours but much of it was trial and error. It can be done in 2.5-3 hours this way.

    So here goes, I tried to make it as detailed as possible:

    1. Jack up the front of the vehicle at least 5", and safely secure it

    UPDATE: Looking back at what I did, it's probably better in this case to climb on top of some small ramps with the front wheels, instead of placing the truck on jack stands.
    I used some blocks of concrete that I had around for that purpose (using 4WD helped climbing on top of them with the front wheels).
    In hindsight it probably positioned the front struts in a more convenient angle, providing more clearance between them and the frame rails, helping with access to the frame rail bracket bolts.
    See photos below to see exactly what I mean.

    2. Remove the the plastic engine splash guard (4 x 13mm bolts)

    3. Remove the 2 upper 10mm bolts holding the fan shroud in place, and pull it up slightly to provide a bit more clearance for the fan to move upwards with the engine

    4. Remove the 2 bolts (10mm) and 2 nuts (10mm) that hold the ECM in place (on the driver side), and move it out of the way (no need to disconnect/unplug any wiring)

    5. Drill a hole in the metal bracket below where the ECM was, exactly above the upper bolt of the driver side motor mount.
    Start with a small drill bit, and gradually enlarge the hole until you can pass an extension socket through it. Make sure you have a large enough drill bit before starting this work.
    This will allow easy access for loosening and removing the upper motor mount nut. See photo of how it should look like.
    (I'd recommend doing this ahead of time as preparation for the motor mount job)

    6. From below the vehicle, support the driver side of the engine oil pan with a jack, putting a block of wood between the jack and the oil pan (I used a concrete brick but wood should be safer). See photo.

    7. Remove the upper 18mm nut of the driver side motor mount using an extension socket running through the hole drilled earlier (see photo)
    This requires a deep 18mm socket, a standard one will not work.

    8. Remove the lower 18mm nut of the driver side motor mount, which is accessible from below.
    Best way is to run the extension and swivel sockets through the hole in the frame (see photo).

    9. On the passenger side, remove the air filter box cover, disconnect the air intake pipe and place it on top of engine (no need to unplug the sensor)

    10. Start loosening the lower and upper 18mm nuts on the passenger side mount, but do not remove them yet. Access is much easier on the passenger side.

    11. Jack the engine up until the fan almost hits the fan shroud. The more you can lift it the easier the process gets later.
    However, be careful not to lift too much, as too much force applied to the fan can damage its bearing or clutch.

    12. On the driver side, remove the frame-rail-to-motor-mount bracket. This requires fully loosening 3 x 21mm bolts that are accessible through the driver side wheel wheel.
    There's absolutely NO NEED to remove the wheel or strut.
    The upper 2 bolts can be accessed using extension sockets + swivel socket, and the lower bolt by using a wrench (I needed to use a hammer with the wrench to loosen it).
    Initially some force is required but then these bolts rotate easily by hand. Rotate the bolts until they clear the threads.
    Steering the wheel to the left or right can help with access. See photos of how this is done.

    13. Both the driver side frame-rail-to-motor-mount bracket and motor mount itself should be free now.
    Gently hammer the upper bolt of the mount from above and the bracket from below to get them unstuck.
    The bracket has guides on top of it so it need to move upwards slightly before it can be removed. Then remove the old motor mount from the truck.

    14. Place the new motor mount in its place, by installing the upper 18mm nut on it by hand (do not tighten it yet).

    15. Maneuver the frame-rail-to-motor-mount bracket so the lower bolt of the motor mount goes through it, and then install the lower 18mm nut by hand, do not tighten it yet.
    Maneuver the bracket to its original location, this requires sliding it from above so the guides fit exactly over where the 2 upper bolts go (I found it easier to do it from below the truck).

    16. Fully tighten the 3 x 21mm bolts that hold the bracket to the frame rail.

    17. Tighten the upper and lower motor mount nuts some more, but not fully so the engine can still rotate to an extent helping with the replacement of the passenger side mount.
    Make sure the alignment pin on bottom of the motor mount is placed correctly into its hole in the bracket.

    18. Lower the engine, then move the jack to support the passenger side of the oil pan.

    19. Completely remove the upper and lower 18mm nuts on the passenger side motor mount.

    20. Again jack the engine up as much as possible (supporting this time the passenger side), until the fan nearly hits the fan shroud.

    21. Repeat the process of replacing the mount on the passenger side (same as driver side) - remove frame rail bracket, replace motor mount with new one, reinstall frame rail bracket.
    There's a heat shield on this mount that needs to be reinstalled in the same position as it was before.

    22. Lower the engine fully and remove supporting jack from under the oil pan.

    23. Fully tighten both upper and lower 18mm nuts on both side motor mounts.

    24. Reinstall fan shroud 2 x 10mm bolts. Be careful not to confuse them with the longer ECM bolts, as using the wrong ones could actually damage the radiator.

    25. Reinstall ECM.

    26. Reinstall air intake pipe and airbox.

    27. Reinstall engine splash guard.

    28. Lower truck to ground

    29. That's it! you're done.


    *** THIS PROCEDURE WORKED GREAT FOR ME. HOWEVER I DO NOT TAKE ANY RESPONSIBILITY FOR ANY RESULTS OF FOLLOWING THESE INSTRUCTIONS ***

    GOOD LUCK!!! Hope you will find this helpful.
     
  2. Uri79

    Uri79 Member

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    Drilling a hole in the ECM bracket to allow a socket extension to go through:
     

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  3. Uri79

    Uri79 Member

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    Jacking up the engine from below, driver/passenger side:
     

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  4. Uri79

    Uri79 Member

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    Access to the driver side mount lower bolt:
     

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  5. Uri79

    Uri79 Member

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    Access to the frame rail bracket 2 upper bolts / 1 lower bolt:
     

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  6. IllogicTC

    IllogicTC Well-Known Member

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    Thank you for this write-up :thumbsup:

    I've been diagnosing some vibration on my TrailBlazer and while before I was curious of a lean condition I thought I had seen, monitoring my fuel trims showed me it wasn't all too bad. Several instances where the LTFT was at 0.0 even, and no misfire code.

    So, motor mounts it is! (maybe) :rotfl:
     
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  7. IronMike

    IronMike New Member

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    I've had my Envoy on ramps for 2 days working on the mounts. I'm stuck because I can't get the motor to rise up off of the old mounts. There's nothing hitting up top, everything has at least 1.5 inch clearance, shroud loose, all mount bolts off, jack/wood block only on oil pan BUT motor won't rise up without immediately bringing the whole front end with it.

    I've had the same vibration problems others have resolved with new mounts. Old mounts have compressed about an inch compared to new. But I'm thinking I got bigger problems and the vibration is coming from some other frame/driveline contact I'm not seeing.

    Is it normal for the front end to rise with the motor for a while (2 inches before I gave up) before the motor rises off its mounts? I'm not too comfy lifting the front end by the oil pan. - Mike

    I
     
  8. The_Roadie

    The_Roadie Well-Known Member

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    Admin Post
    On a 4WD, I found the inner CV joints hitting the top of the frame rail opening they go through. Consider removing your CV shafts from the diff (driver's side) and the splined disconnect (passenger side). Easy to spot if this is happening.

    [​IMG]

    [​IMG]
     
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  9. IronMike

    IronMike New Member

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    OK got mine done but it took me over 10 hours because I'm an amateur and overly cautious. This is probably the first repair where I would say ida been much better off hiring it. So my two cents to other newbs considering this:


    1. On a 4x4, no way you're gonna get mounts out or in without removing a mount bracket on each side. I went for the upper brackets that attach to the engine based on a different DIY guide. Huge pain, so go for the lower frame-side bracket as per Uri's guide above.


    2. You gotta jack til the wheels almost come off the ground before the engine rises enough in the bay. Initially the engine won't appear to rise at all since the suspension is going to bring the frame up because YOU are removing the engine weight (yeah... obvious now).


    3. I checked for CV clearance as per Roadie (thanks!) and it was good. But at one point I may have over-jacked the engine and stressed either the CV shafts as Roadie warned or the fan shaft as Uri warned (so much for overly cautious). I've develop a low rumble from the front end that I'm guessing is from a CV shaft or the fan clutch. It starts at about 20mph. So another obvious tip... don't crank too high.

    Repair was a success tho and the ride is smoooooth. - Mike
     
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  10. Uri79

    Uri79 Member

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    Hi Mike,

    I've just seen the replies to this thread now, hope that by now the fix went well.

    Yes, the front end of the truck will rise a bit before the engine starts rising.

    It could be that the mount upper or lower bolts are sticking to their place even after the nut is removed and the engine lifted, so carefully hammering the bolts could help free the mount.
    I've used a small hammer together with extension sockets for this purpose.

    Another thing to watch for is that the block of wood used to support the engine from below, is not positioned in a way that's also contacting and lifting the frame member behind the oil pan.
     
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  11. bLAzen03

    bLAzen03 Member

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    One word Awe-Some! I just did this repair this past weekend and now my TB is as smooooooth as ever.

    So prior to this, I had checked the plugs (they're fine), Cleaned throttle body (It's really shiny now), checked for vacuum leaks (None found).

    This was my last resort, so I went to the dealer and bought the OEM's ($99.36ea) popped them in and WoW :yes: what a difference they made, now it idles perfect even with the A/C on.

    A few things I did different though,

    I did not drill a hole on the bracket under the ECM, I found I had long enough extensions & a swivel socket that worked great, didn't even have to remove the actual ECM.

    I removed the 3 21mm bolts from the bottom of the vehicle with a ratcheting wrench rather than using extensions. The extensions would have only worked if I did not have the TB on ramps, It compressed the springs too much.

    Overall it was worth it. I took a few pictures of the socket I used & bracket.
     

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  12. Jerseydevil20

    Jerseydevil20 New Member

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    Big, big thanks to Uri for posting these instructions!

    I Had the same horrible vibrations and performance issues that others have described. First thought it was a trans problem. Realized it was probably motor mounts. Was a little intimidated... I'm not a mechanic, but I'm also not afraid to try things. Ordered GM mounts from Amazon, read everything I could find on here and the "other" site. I tackled this with 2 buddies yesterday. Job took 5-1/2 hrs. TB runs like a dream now. So smooth!

    I followed Uri's instructions closely. Here are my notes. Maybe it helps the next guy:

    - my passenger side mount was failed. Driver side was not, but I replaced both. I think this is wise so there is balance. The pass side has the heat shield on it; I assume this contributes to its failure (the heat).
    - do the driver side first as Uri notes. The first mount goes in easier (the new mount on one sides limits the rotation you can create when you lift the engine) and the drivers side is much more challenging than the pass side.
    - there's no need to cut off any of the new mount as others describe if you remove the lower bracket. In fact, you don't have to jack up the engine as far either. I only jacked it up high enough to have the fan blade touch the shroud. There's no need to risk bending anything related to the fan or fan clutch. I also never got close to having the CV touch the frame.
    - I did put the truck on stands and removed the tires. Made access easy. Also took off the splash guard in the drivers side wheel well. I think it made access easier, but probably not necessary.
    - didn't have to remove the bolts that hold the lower bracket (they are completely loosened so the threads are out of the bracket). The springs block their removal, but they back out enough to just clear the bracket so it's ok.
    - getting the bracket back in the slots is a challenge. Keep working it until it falls just right. After you get the bracket back in, make sure the mount lines up with guide in the hole in the bracket.
    - I drilled the hole in the pcm bracket. Made it much easier.
    - if you use a floor jack, make sure you check it every once in a while as it will "sink" over time. You need every 1/4 inch of clearance you can get (fan blade should touch the loosened and raised shroud).
    - need an 18mm deep socket and a 21mm wrench. Also, needed a 3/8 breaker bar to get the bottom nut loose on the drivers side motor mount (the angle was tough). I didn't need impact tools.
    - hit the bolts with some pb blaster a few hours ahead of time

    Thanks for the assist Uri! This place is awesome. This repair is very doable.
     
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  13. triz

    triz Well-Known Member

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    I did this just this week. I had a issue with the drivers side mount. I did not remove the bracket mount, but I did remove the top two bolts and loosened the bottom one to allow the bracket to move enough to get in the mount fully. I also used a swivel socket to remove rather than drill.
     
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  14. 6716

    6716 Well-Known Member

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    I used a ratcheting 18mm combination wrench to get the top nut off the driver's side mount.

    I also pulled the struts to make the 3 bracket bolts easier to work with.

    By taking the brackets off, I didn't have to lift the engine very much and I didn't have the CV boots run up into the frame.
     
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  15. latin

    latin New Member

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    I also got some vibration on mines 2003 Isuzu Ascender, all my mounts arrived this week including the transmission one lets see how things turn out. TY so much for the advice, this will be the first time for me to mount them on my truck. Hopefully i can get it done shortly, I'll post when I'm done.
     
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  16. latin

    latin New Member

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    OK guys, big thx to Uri 79, bLAzen03 and IronMiike took all your advises. checks the brackets and since mines is a 2WD I only loosen the top brackets which is (4) 14mm bolts on both side (Driver side then passenger side). First I removed both top and bottom motor mount bolts with a deep 18" mm socket, I lifting the engine as high as I can without removing fan clutch and without removing the shaft. I did remove ECM and did the top hole with a hole maker using electric drill and a whole make socket, this only took about 2 minutes, the hole was very simple. Used a swivel adapter with a 3/8 Ratchet with a 18" extension tool bar and 18" deep socket, then used 3/8 Ratchet with a 6" extension tool bar and a regular 14" socket on both top mount top brackets and just loosen them where it dance in place without removing bolts. I didn't need to remove the tires, this did take me about 5 and 1/2 hours, but it was worth it. Engines is running smooth feels like new. Thank you all for those good ideas, this help me get my truck's mount install much easier. I will put up pictures of the tools I used and the hole I made to make it much more easier, hope who ever follows in doing this just take a few pointers from everyone on here before proceeding and you will see it might take a while, but you will get the work done,

    TnX to all,

    Latin
     
  17. JCarlson

    JCarlson New Member

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    2.5 hours. Passenger side a bit more difficult to get off and on. You really have to get the motor lifted! Your post helped a lot and saved me some money. Thanks
     
  18. Mirror

    Mirror Well-Known Member

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    Just did this today but driver side only since i had a bad banging noise on that side.

    Had to take tire off and pull back strut assembly about an inch or so in order for bracket bolts to clear the spring. Having a 3" seems to be the issue with that.

    Started at 9 finished by 12:30.
    (Pissing around trying to get the bolts out before pulling strut back)

    Noise seems to be gone now.
     
  19. AzTruckGuy

    AzTruckGuy Well-Known Member

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    Just scored 2 brand new GM OEM motor mounts for $30 and since I am doing new struts and front and rear rotors and brakes, should make the job easier to do the motor mounts with all the items I have to take off. I assume the lower 3 bolt bracket hold the motor mounts in place? I haven't taken a look yet on my Trailblazer
     
  20. 07TrailyLS

    07TrailyLS Well-Known Member

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    Not sure if URI is even on this site anymore. But I would like to give a huge thanks to him. Followed this guide his morning and I was able to do both replacements in under an hour and a half. So here's to you brother
     
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