Mounting up the motor

In my last post I replaced the transmission mount and crossbrace bushings.  Next on my list of aging rubber to replace was the motor mounts.

When researching how to replace the mounts, the shop manual describes supporting the engine from above.  While I do have a shop crane, I didn't want to remove the hood to use it (the hood on a 280z opens towards the front of the car).  Others suggested that the engine could be slightly raised by placing a thick piece of wood under the oil pan and use a floor jack.  I felt that replacing the mounts from the underside of the car would be easier, so I decided to use a transmission jack under the oil pan with a 2x8 cut to the width of the oil pan to lift it.

After inspecting all of the items fastened to both the engine and the chassis, the air intake boot was the only bit that I felt it necessary to disconnect in order to lift the engine a couple of inches.

I began by removing the driver-side engine mount bolts and positioning the transmission jack underneath the oil pan.  I then loosened the passenger side engine mount and the transmission mount.  I slowly raised the jack until the engine mount began to lift.  

Several times I climbed onto a ladder to check for stressed engine components but found none.  The removal of the old mounts was not difficult once I got the courage to raise the engine high enough.  Installing the new mounts, however, did come with a few challenges.  The new mounts differed from the original mounts in two ways:

1. The new mounts did not include weld nuts under the mounting holes.  In order to install these I would have to supply my own bolts and nuts.
2. The new mounts did not accommodate the bracket that must have been added in later engines that protects the engine from moving forward or backward when the mounts break.

To accommodate the protective bracket, I simply had to cut a bit of rubber from the top side of each mount.

Once the new mount was in position, I lowered the engine until it was close to resting on the new mount.  I did this to ensure that I had some ability to move the mount in order to put the new bolts into place.  As it turns out, securing the new mounting bolts, washers, and nuts was the most difficult part of the job.  With the movement protection bracket in place, I needed fingers the size of a small child to hold the washers and nut in place.

Eventually I was able to start the nut on the threads.  Once all nuts were started I lowered the engine completely and torqued the nuts to spec.

When inspecting the old mounts, it was apparent that they were ready for replacement.  The rubber had cracked and begun to separate from the metal base.

With these and the transmission mount now replaced, I will be curious to see if the clunk when shifting still exists on the next drive.