new motor mount vibration

Clearly if this started right after the mount was replaced then we have to suspect it was a faulty mount. This happens when the mount is grounded which is basically the rubber is not insulating the engine pulses from the frame. If this is metal to metal or just a faulty mount it will transfer the pulses to the frame and you will feel it.

Here are some guides that help with this:

https://www.2carpros.com/articles/how-a-motor-mount-works

https://www.2carpros.com/articles/vibration-noise

Again, if this was after the replacement then I would have it inspected again because either that mount was not installed correctly, was a faulty mount, or you have another mount that failed.

Let me know if you have questions. Thanks

it was just after the mount was replaced. it is a hydraulic motor mount.

This sounds like a misalignment or preload issue, what I would suggest you do first is back off all the engine mounts and run the engine in forward and reverse gear with your foot on the brake, cycle through the gears including reverse as this can help settle the engine and transmission into a neutral load position. Retighten all mounts and road test. If you still experience any vibration, ensure the remaining mounts are serviceable. For solid mounts, apply some load to the engine adjacent to each mount and look for excessive movement and with hydraulic mounts excessive movement and signs of fluid loss.Please post back on this thread if you still experience any problems. Thank you for using 2CarPros.
Mark (mhpautos)