Shaking the fillings out of my molars

[ashvolvo]

The hydraulic mounts on the front and rear of the engine do not do much in terms of vibration, as I found after changing them last month ( they had collapsed on my S70 but had not broken). My engine was rocking when I would accelerate or decelerate. Now that the new mounts are in place, the acceleration and slowing down is lot more smooth and the ride quality for that period is day and nigh difference. The vibration damping happens mostly on the upper torque mount and to a an extent by the lower engine mount ( next to crank shaft pulley, Part # 9480189). I have not been able to figure out what the rear engine torque rod mounts are for.

[oragex]

They prevent the engine from 'tilting' (rotating) under acceleration. It may help extend the life of the exhaust components including the flexible downpipe. Volvo spent quite a bit on that upper torque mount design with that huge and heavy transverse bar installed only for this mount. Quite a weird design. On the P3 there is still a huge upper torque mount, at least they got rid of that transverse bar. Still, Volvo has a particular approach on these upper torque mounts, I don't remember seeing this on other car brands.

[CedBobKing]

Okay, I have a follow up report.

Recall that I started with an ATF swap, which is stupidly difficulty in this car, because the idle vibration worried me that the transmission might be developing issues. I swapped the torque mounts because I knew they were shafts suspended in holes by only a hint of material in-between.

First, i swapped the urethane back out for the old EPDM upper torque mount so I could stand to drive the car. I still would change into manual mode to keep the engine speed around 2k revs or above. At speed it was fine.

Second, I ordered a new Meyle EPDM front, rear and passenger side engine mounts from FCP Euro, because they had them on sale!

Third, I replaced them with the following procedure (https://youtu.be/UA7qjGjg8Yc), re-installing the IPD urethane torque mounts in the processes.

Here is the interesting bit. Upon exposing the passenger-side engine mount, the nut for the crank accessory belt pulley fell to the floor. I paid a shop to swap the timing belt, water pump and accessory belt about 50k miles ago. I was pretty happy to still have the nut.

After assembling everything, new front, real and passenger EPDM motor mounts, along with new urethane upper and lower torque mounts, and installing the crank nut, it is now a smooth running car again. There is some mild vibration when stopped at idle, but is is probably better then when I bought the car with 114k on it.

I will probably replace the mounts on that cross bar sometime.

The passenger side mount seemed iffy, but the front and rear ones seemed okay, but I did not attempt to test their compression. They are certainly not hydraulic just a stud and nut hole buried in some EPDM the size of an apple.

The source of the vibration was probably the accessory belt pulley.

I am pretty happy with it now.

[scot850]

Glad to hear you have found a sweet spot of vibration and smoothness.

Neil.

[CedBobKing]

Although I was okay with the small low speed vibrations, the wife was not. So I bought new OE strut brace mounts, top mount and transmission mounts. Now the car rides as smooth as butter.