Happy Ending to Motor Mount Saga

[RustyH]

2000 Volvo S70 NA; 97,000 miles.

I thought I would refresh the audience from an older post on this subject.
My wife's car is a 2000 S70 NA, bought it new. I can't remember exactly when the idle noise/vibration started but it was when it was relatively new. We never inquired about this because it really didn't bother us so much. Over the years, the idle noise (low pitched) gradually increased with subtle vibration in the pedal and steering wheel that only the driver really experienced. I brought this to the attention of the local Volvo dealer when we were having the car serviced for another reason. They suspected a bad motor mount and the upper engine mount was replaced in 2006 at a mileage of 74,000. This helped some, but did not eliminate the noise. Over time, this idle noise/vibration progressed, and I started reading and learned that the right lower mount (front of engine) is freq a problem, and that was changed 2/2007. There was no improvement. Like a dummy, I pursued this as it really irked me to buy a $30,000 vehicle with this kind of uncivilized behavior. The idle noise progressed to a deep roar which occurred 1-2 sec after stopping in Drive and would stop as soon as brake released. The roar was very uncomfortable to my ears, and it was loud enough that ordinary conversation in the car was difficult! Somewhere along the way, it developed another growl which I heard best from the center of the dash when launching and would disappear after a few seconds. So, I purchased both hydraulic mounts (aftermarket--Uro something) and asked my local indy shop (well-respected) to put those in. The shop owner really didn't want to and said all Volvo's do this and feel this way. The right (rear) mount (referring to engine) was put in first and the noise increased substantially and now we could feel terrible vibration in the cabin. We had to take the car that evening and had indy put in the left (front of vehicle) mount at a later time which helped some, but honestly it was worse than when I started all this nonsense. After that I changed the transmission torque strap and replaced the the front (crankshaft) mount without improvement. I did get the launch growl to stop after changing the donut firewall mount. By the way, the hydraulic mounts all looked fine to my indy, and the other mounts all looked fine to me including that donut mount.
Along this journey, I had read about subframe bushings and read "Roncar" (see brickboard forum) experience with his XC70. He indicated that there is a TSB (only in the UK) on these subframe bushings for large platform Volvos and that an improved (stiffer) subframe bushing had been made in the UK. (They apparently complain more than we do!) I talked to my indy about this--he was fourscore against this, but happy to take my money since I insisted he have it. So, my indy put these in after borrowing the special tool needed to remove and place these in. He has a big shop and it took the tech 4+ hours to do this. They wanted to take their time since they have never done this before. I did see these bushings--they come as a kit and yes, they are made in the UK. There was an improvement in the idle noise/vibration but still not satisfactory, but the deep irritating roar was gone. I suspect if I had not done the hydraulic mounts, I would have a quiet idling vehicle.

The above was edited from an old post. To continue my saga...
I still was not at all satisfied with the degree of idle noise and vibration and by the way, it was much worse in colder weather. I remembered something my mechanic had asked and that was did I purchase Volvo mounts. I told him no these were aftermarket mounts. I decided to review the part numbers and sure enough the rear hydraulic mount from IPD that I purchased (3507996) was different from a few other internet part suppliers which listed 6801722 as the correct number for my chassis.. There is a part number difference depending on chassis number. IPD website does not show this chassis break. I confirmed the correct rear hydraulic mount number with the dealer and purchased it from the dealer. (I was able to negotiate some on the price--$120). This mount has the Volvo logo stamped on it. Anyway, I asked a local tire shop (they also have a few mechanics) to put this in. I had already written out how I thought this was to be done (I'm not a mechanic). They ignored me and put this thing in within an hour. They made it look easy. After disconnecting the top torque mount and removing the nut from the rear hydraulic mount, they lifted the car. They disconnected the transmission torque strap and then used two jacks--one under the oil pan, and one under the transmission close to the rear hydraulic mount and raised engine and transmission slightly. They loosened the bracket that the mount goes in, joggled out the old mount and joggled in the new mount. Then, put bolts back in, reconnected everything and we're done.
The Uro mount cable slid right off indicating to me that it had failed. (there was no pulling or prying to get the cable off--again, it was loose enough it just slid right off). That mount was put in 10/2007 so only 18 months in service and failed!! But of course it made my idle vibration/noise worse immediately when it was installed. I don't know the difference between 3507996 and 680172, but there was about a 1/4 inch height difference to my eyeball when I had the two side by side with the new one (680172) taller.
And the verdict--it's wonderful!! Idle vibration/noise, variety of groans, squeaks, and slight transmission shudder when the gears shift are all gone! Well, I exagerate a little. This vehicle does not idle like my BMW with in-line 6; I don't hear or feel anything when it idles. But, that was not my expectation anyway with the Volvo.
Here's what I learned:
1. I do think the UK subframe bushings helped, but my regular mechanic said they were a bear to put in. If someone wants to pursue tracking down idle vibration/noise, I'd think about doing this early in the process.
2. Original hydraulic mounts looked good per my mechanic. If I did all this again, I would not replace these.
3. I should have used only VOLVO mount mounts. I found a post on another forum where JRL mentioned that--wished I had discovered that early.

[MadeInJapan]

You are talking about the rear hydraulic subframe mount, right? The one with the wire attached to it? Just wanting to clarify. I have vibrations too and would gladly change it if this is what it takes- all of my mounts look great, btw.

[RustyH]

Yes, this is the rear (in terms of vehicle orientation) hydraulic mount. And yes, it has the cable that goes around it. I still have the aftermarket front hydraulic mount. I'll take a look at it next and see if it has collapsed also. I only replaced the rear because it was the wrong part number.