Broken Motor Mounts

[Kenny D]

I went ahead and purchased the Anchor brand from Advanced. Lifetime replacement plus, I get a 20% cash back through my bank rewards. I know I paid 3 times what they were on RockAuto, but they are just down the street when I need another. By the way, I stored my receipt in a cool dry place for preservation. Now just to schedule a day to install it.

 

[iamdub]

You should scan and print your receipts because the print on the thermal paper will still degrade and fade.

 

[Da90]

So I replaced the mounts in my Denali when I first bought the truck. They lasted less than a year. I wasn’t going to replace them again until I found a fix.

I may have let my motor mounts go a little longer than I should have.

On to the carnage and solution.

Driver side



Passenger side



Solution. I first notched the heat shield. I then took two pieces of 1/8” x 1” strap steel and welded it to the bottom crossmember bracket and the bracket that bolts to the block. I sure hope this works cause the Suburban we bought a few months back also has broken motor mounts.






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[08grey]

Thats gonna feel like a solid mount. You need some play.

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[Meccanoble]

So where is the point of failure? I dont know enough about mounts but sounds like its not the rubber thats failing. I believe tougher mounts would lead to more vibration? What made you decide to go this route? The rubber is not failing but instead the mount is breaking at the metal? If so, why would reinforcing the break points not work? Isnt it the rubber that is doing the playing?

 

[Da90]

Thats gonna feel like a solid mount. You need some play.

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I was worried about that. No vibration whatsoever! Feels just like stock.


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[Da90]

So where is the point of failure? I dont know enough about mounts but sounds like its not the rubber thats failing. I believe tougher mounts would lead to more vibration? What made you decide to go this route? The rubber is not failing but instead the mount is breaking at the metal? If so, why would reinforcing the break points not work? Isnt it the rubber that is doing the playing?

The point of failure is the rubber. Too much flex. This is a picture of original mounts that I replaced first.



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[08grey]

The point of failure is the rubber. Too much flex. This is a picture of original mounts that I replaced first.



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Here is a solid mount a member on another forum made.

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[08grey]

I have a new mount on the shelve right now I need to Install. How much to send it to you to add the steel? I'd be down to give it a shot.

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[iamdub]

So where is the point of failure? I dont know enough about mounts but sounds like its not the rubber thats failing. I believe tougher mounts would lead to more vibration? What made you decide to go this route? The rubber is not failing but instead the mount is breaking at the metal? If so, why would reinforcing the break points not work? Isnt it the rubber that is doing the playing?

The mounts are hydraulic, so they're basically oil-filled balloons. This is great for damping the vibes when running in 4-cylinder mode, but insufficient for the engine's torque when moving such a heavy vehicle. Trucks that tow tend to break the mounts much sooner. Over time, the rubber hardens so it isn't as flexible/elastic and it cracks. The fluid leaks out so now there's just a small amount of dryrotted rubber acting as the cushion which is hugely insufficient. This rubber is easily and excessively stretched and squished constantly from the engine loading and unloading, so the hard parts inside the mount are able to wallow themselves out some wiggle room. Eventually, there becomes a void where it's just metal on metal and the halves of the mount are like two links in a chain hanging freely then being abruptly pulled taught every time the engine torques.