How are Trans Mount issues diagnosed?
There are a couple of things that will be checked when a transmission mount is suspected of failure. First, with the engine on, the technician will have a helper shift the transmission from reverse to drive several times to search for excess movement, noise, and to measure the vibration in the cabin of the vehicle. This is done with the understanding that a bad transmission mount will make the most vibration in gear with the vehicle stopped. Next, if excess vibration or movement is detected. The technician will visually inspect all mounts for signs of past leakage. This is only done for liquid filled mounts. Afterwards, even if no leakage is detected, the mounts will be manipulated with a prying tool. When the mounts are moved, they will give the technician an idea of the firmness of the mount, and allow any cracks or deterioration to show. If the mounts fail any of these checks, they will be replaced.
How are Trans Mounts replaced?
The engine and transmission must be supported, and this may be done with a transmission jack or engine brace, depending on the location of the mount and the orientation of the drivetrain. Once weight is removed from the transmission mount, the bracket will be disconnected from the transmission, then the housing will be removed from the chassis. Note that some subframe components or chassis crossmembers may need to be removed. The new mount is placed into the vehicle, attached first to the chassis, then the transmission is positioned in line with the new mount before bolting the transmission to the metal bracket extending from the rubberized insert. In some cases it may be necessary to adjust the other mounts for proper fitment, as the failing transmission mount can cause small movements to occur for the other mounts.
RepairPal Recommendations for Trans Mount issues
We recommend having the motor mounts inspected at major services. This should already be on the maintenance schedule, so follow the owner's manual guidance concerning the inspection and repair intervals. In general, transmissions require fluid and filter changes at the same interval they require transmission mount inspections.