Should engine mounts be replaced in pairs? 2010 Yukon Denali

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TooManyGMCs

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Vehicle: 2010 GMC Yukon Denali XL AWD 172k

I recently discovered that what I thought was transmission problems is actually a badly broken engine mount. The drivers side of the engine was lifting approx. 3" when we did the test to see if it was in fact a bad engine mount. I went ahead and ordered an Ac Delco one (as tempting as the Chinese ones for 1/4 the price were) but then I started wondering if it would really be best to change them both at the same time.

What's the general rule - should I just do one and hope the other is ok and holds up or should u bite the bullet and do both?

Thanks for any advice!
 

08HoeCD

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I don't know if there's a rule, but if the setup on your engine is the same as that of the 5.3, the driver-side mount suffers more potential damage from 'stretching' during the power stroke versus the passenger-side mount (as that side is compressed slightly during the power stroke). the 'stretch' dynamic essentially tears the mount apart over time; whereas the compression typically does little to disintegrate the mount.

At the end of the day, however, if devoting the time & effort to tackle replacing one mount, it's not like it's twice the work to replace both.

You'll get more detail and advice from those who know more, as there are many on here who have had to go down this path.
 

swathdiver

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At that mileage, I'd do both, especially since the driver's side was in such bad shape. Would do the transmission mount too. Replacing all the mounts at the same time was my SOP with my last RWD/4WD vehicles and when the time comes, will probably do them all again at the same time.
 
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TooManyGMCs

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Guess I should have specified engine too. I've got the 6.2 guessing that probably makes a difference.
 
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TooManyGMCs

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I don't know if there's a rule, but if the setup on your engine is the same as that of the 5.3, the driver-side mount suffers more potential damage from 'stretching' during the power stroke versus the passenger-side mount (as that side is compressed slightly during the power stroke). the 'stretch' dynamic essentially tears the mount apart over time; whereas the compression typically does little to disintegrate the mount.

At the end of the day, however, if devoting the time & effort to tackle replacing one mount, it's not like it's twice the work to replace both.

You'll get more detail and advice from those who know more, as there are many on here who have had to go down this path.

Thanks for the reply.

Guess I should have mentioned engine as well. It's the 6.2 so not sure if your info applies to that engine or not. But your answer is kind of what I was imagining when I initially bought just the 1 mount.
 
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TooManyGMCs

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At that mileage, I'd do both, especially since the driver's side was in such bad shape. Would do the transmission mount too. Replacing all the mounts at the same time was my SOP with my last RWD/4WD vehicles and when the time comes, will probably do them all again at the same time.

Thanks for the reply.

How difficult is the tranny mount to change out?

I can definitely agree with the idea of change em all if I've gotta do one.
 

swathdiver

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Thanks for the reply.

How difficult is the tranny mount to change out?

I can definitely agree with the idea of change em all if I've gotta do one.

Haven't done any of them on this platform myself yet. There are several "how tos" on this forum with pictures though, not too bad. One side is more tedious than the other.
 

wjburken

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If I recall correctly, the tranny mount is fairly straight forward. Just need a jack to lift the tranny tail off the mount once you get the bolts out.
 

r870

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The drivers side tends to see more damage, as others have said because it gets stretched instead of compressed.

Mine went bad pretty early, probably around 80K miles. I replaced the drivers side only, and have 195K with no issues.

I tried replacing it myself, and it was a huge pain. The bolts are pretty tough to reach and at weird angles, and you have to lift up the engine to get it out. Probably not super tough with the right tools, but for me in the driveway with just hand tools and socket wrenches + extensions it was a challenge.
 

91RS

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At that mileage, definitely do both. The left one breaks but the right one will collapse over time and allow excessive vibration from the engine to be felt.
 
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