I had this near violent vibration on taking off in first and thought it could be the bearing in the driveshaft or even the tranny. The tailpipe was hanging real low - six inches above the pavement. So I jacked up the tailpipe in the middle and secured it with very strong wire braids. This took the violent vibration away because it turned out that the right motor mount was collapsed - and this made the tailpipe sag and vibrate. I got a new motor mount - got the front wheels on ramps and disconnected both bolts on the right motor mount and tried jacking the engine up - I expected the engine to pivot on the left motor mount - and get enough room to take out the old and insert the new right motor mount. But jacking up on the right side of engine actually started lifting the entire right side of the car off the ramp. So - seeing that this was dangerous, I put everything back together and came here to ask;

what prep is involved in loosening the engine so that it will lift enough to replace the motor mount? If I detach both right and left motor mount retaining bolts, will this allow the engine to tilt up off the frame to get the mounts in? Is this dangerous to the tranny alignment? Thanks!

 

** I was assuming this was on a 240

I would jack it up evenly and it should lift about 3 inches with plenty of room to remove and install the mounts. Recommend doing one mount at a time. You may not need to replace the driver side mount.

I did this recently on my 90 240. First buy OEM Volvo motor mounts and think about getting the passenger side diesel mount. After much research and procrastination I plunged in on this repair. I feel the most important factor on this job is safety. Not worth the motor falling on you. After this repair you will be amazed how much better the car rides.

Placed the front of the car on ramps
Drain motor oil
With oil drain plug removed place wood block under 3 ton jack
Attach engine support bar and tighten to engine hoist attachment
Raise motor and keep adjusting engine support bar - be careful
Front of engine will start to pull up. I went about 2 to 3 inches.
Removed bottom bolts first
Removed oil filter
Remove top bolts
Note - I left the top bracket attached to the motor. Note sure about others.

Have a Dremel tool ready! I had to cut off the top motor nut as it was seized.

1000 Lb. Capacity Engine Support Bar

 

tox_slaughter - Thanks for the detailed reply and all the information.