Motor mounts failure modes.
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2004-2007 Cadillac CTS-V General Discussion Discussion, Motor mounts failure modes. in Cadillac CTS-V Series Forum - 2004 - 2007; At slightly over 40k, I'm starting to experience some unusual vibrations from the V. What's unusual is that it happens ...
  1. #1
    bolide is offline Cadillac Owners Member
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    Motor mounts failure modes.

    At slightly over 40k, I'm starting to experience some unusual vibrations from the V. What's unusual is that it happens when the motor is torquing in reverse. I get shakes and chatter when I back up but is perfectly smooth when engaging in a forward gear. I also experience it (albeit in a smaller degree) when braking or when the drivetrain is driving the motor. Which motor mount is shot? Or maybe I should say in worse shape. Are these mounts mechanically locked even if the rubber separates or can it completely come apart and cause major engine movement? Also I'm starting to experience reverse lockout failure, which I think is more like the solenoid sticking. It doesn't do it in the summer at all, but once the cold weather starts it allows me into the reverse gate until the tranny is warm, then it works as it should. I wonder if removing it and spraying some penetrating oil in there would solve the problem.
    Anyways just fishing for info. If anyone has any input, I look forward to it. Thanks.

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    darkman's Avatar
    darkman is offline Cadillac Owners Master
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    Re: Motor mounts failure modes.

    These motor mounts are liquid filled and failure results in a brown residue (leaked fluid) at the motor mount and below.

  4. #3
    JDB's Avatar
    JDB
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    Re: Motor mounts failure modes.

    Flush the clutch fluid.

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    OneFast V is offline Cadillac Owners Enthusiast
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    Re: Motor mounts failure modes.

    my motor mounts just came out last night. there was no fluid left inside or evidence of brown residue, it looks like it dried up inside. the top of the rubber is also totally separated from the rest of the mount. They really didnt look bad until they were removed.

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    bolide is offline Cadillac Owners Member
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    Re: Motor mounts failure modes.

    So if you grabbed the top stud could you separate it completely from the bottom stud, or are the two mechanically captive inside the rubber housing? Pics?

  7. #6
    CadzillaTN's Avatar
    CadzillaTN is offline Cadillac Owners Connoisseur
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    Stock mounts can't separate..just google the forum site and motor mounts, you'll get some pics

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    OneFast V is offline Cadillac Owners Enthusiast
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    Re: Motor mounts failure modes.

    IMAG0151.jpg

    Here are my failed motor mounts. I believe the bolt might through the entire mount?

  9. #8
    PISNUOFF Guest

    Re: Motor mounts failure modes.

    The stud doesn't go through the entire mount. If it did, there would be no need for the oil or the rubber. Mine failed just as the picture above and the oil is in a separate 'cavity' from the stud that you see in that pic above. I poked a hole though the rubber underneath where the stud pulled away and the oil leaked out. It is possible that the entire thing could come apart and not support the motor.

    Bolide - I would flush the clutch fluid properly, this should fix your reverse engagement issue. If it doesn't fix it, the reverse lockout solenoid is not terribly expensive and is pretty easy to change.
    I would swap the rear diff fluid, making sure to add the limited slip additive, and see if the chatter in reverse goes away. It doesn't sound to me like a motor mount symptom, but anything is possible. It sounds more like a CV or limited slip issue, although you need to tell more about how the vibration/chatter feels and exactly when it happens. Does it feel like it's coming from the front of the car? When in reverse, are you backing out of a parking spot with the wheel completely turned or just backing up in a straight line?

    If it is a motor mount I would suspect it to be the driver's side as that side of the motor pulls upward as the motor is creating torque. If I was replacing my motor mount because I thought it was worn out or damaged I would replace them both. If you don't want to replace them with the stock ones, people have found success swapping both sides with different mounts (polyurethane/solid/oil filled) to reduce the amount of vibration transmitted to the chassis.

  10. #9
    CadzillaTN's Avatar
    CadzillaTN is offline Cadillac Owners Connoisseur
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    The stocker can't separate.

    Think of it like this, the bottom half is like a 'bucket' with a top lip that is narrower in diameter. On top of this lip sits a layer of rubber that dampens vibration between the 2 halves. The bottom of the top half of the mount is an inverted mushroom shape that contours with the bottom of the bottom half's bucket, and can't escape the bucket's top metal lip.

    It 'could' separate, but the force required is far more than you will produce in the engine bay. (try cutting one of them open)

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    bolide is offline Cadillac Owners Member
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    Re: Motor mounts failure modes.

    Thanks for the feedback guys. I don't have an issue going into gear, I'm not suspicious of the clutch at all. The issue is as I slip the clutch to get the car moving( in reverse only), I get a vibaration that permeates the whole car. This only happens for that brief period when the engine is torquing over, and it only does it in reverse, not in a forward gear. Obviously when moving off in a forward direction, the engine wants to twist so that it tends to separate the driver's side mount, and when moving off in reverse it does the opposite, compressing the driver's side.Thus my question. I'm trying to visualize what's going on here, and failing motor mount/s seems to fit the symptoms best. Having said all this, I don't have any dieseling effect, no abnormal drivetrain clunks ( at least no more than what's de riguer for a V...lol), and the engine doesn't seem to move that much when revving in neutral.

  12. #11
    PISNUOFF Guest

    Re: Motor mounts failure modes.

    Quote Originally Posted by CadzillaTN View Post
    The stocker can't separate.

    Think of it like this, the bottom half is like a 'bucket' with a top lip that is narrower in diameter. On top of this lip sits a layer of rubber that dampens vibration between the 2 halves. The bottom of the top half of the mount is an inverted mushroom shape that contours with the bottom of the bottom half's bucket, and can't escape the bucket's top metal lip.

    It 'could' separate, but the force required is far more than you will produce in the engine bay. (try cutting one of them open)
    I wonder how mine separated then? Weird.

    Let me clarify, it was in two separate pieces but the upper piece was still captive inside the lower 'bucket'.

  13. #12
    CadzillaTN's Avatar
    CadzillaTN is offline Cadillac Owners Connoisseur
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    Oh ok. You are correct, in that context they'll definitely separate, but the two pieces themselves will stay connected.

    I was thinking can one piece completely remove itself from the other...for a brief moment in time that became a motor mount standard of safety measurement.

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