Upper Engine Mount Bushing Tutorial Overview
The 850’s upper engine mount is designed to hold the engine in place. Without it, the engine would thrash back and forth in the engine bay and damage nearly everything near it. There are two lower engine mounts that are responsible for the engine’s weight, but these are out of scope for this How To section. It’s easily spotted at the top of the engine a bit to the driver’s side (North American).
When it decays, the results can vary from engine vibration felt in the cabin to violent shake and sounds from the engine bay. The upper engine mount, as it comes from the factory, is a molded rubber piece a little smaller than a baseball. This web page shows you how to replace this with an an OEM upper engine mount bushing. On the other hand, if you’re replacing the bushing with a replacement polyurethane mounts, you should use Replace your Upper Engine Mount w/ a Polyurethane Bushing.
- 1 5″ threaded bolt and nut in 3/8 or 7/16 diameter
- 2 pipe flanges for 1″ pipes
- 2 1″ washers (get the thicker ones)
- 1 3/8″ washer (get the thicker ones)
- 1 2″ diameter ABS pipe coupling
Total cost for the above parts = approx CAD$10.00.
Installing the Volvo OEM rubber bushing takes more work than the 2-piece poly-urethane bushing mainly because the OEM is a 1-piece bushing that requires a pressing tool to force the bushing into the mount. Attempting to mount the bushing by hand is extremely difficult if not nearly impossible. Fortunately, Some ingenious fellows on the ‘net have come up with a variety of home-made pressing tools that can be assembled with a few dollars.
The one I used is patterned from a pair of pipe flanges, a 5″ threaded nut & bolt and a couple of washers. I’ve also included an ABS pipe coupling commonly used for joining/coupling 2 ABS pipes together. This is to act as a spacer if you want to perfectly align the bushing within the mount. More on that later. Installing the OEM bushing usually requires the removal of the torque arm (the black “fork” that runs between the bushing and the firewall) in order to make room to accommodate the installation of the bushing and the pressing tool. This is the first thing you should remove.
Locate the bolt that secures the torque arm to the firewall side – it is installed from under rather than from top – use a 14mm socket to loosen the bolt. This will require considerable amount of force because the bolt has been coated with a thread locker (to prevent the bolt from loosening via vibration). Some recommend heating the bolt to breakdown the thread locker. In my case, I soaked the nut and bolt with WD-40 and let sit for an hour and then made a go at it.
With a 14mm socket on the bolt head and an open-ended wrench on the nut, give it a strong twist. *Note that the nut is welded to the torque arm – so do not attempt to loosen it with the wrench*. The wrench is to keep the nut steady while you apply the force on the bolt.
When you’ve done the above, the next thing is to remove the nut and bolt that runs through the bushing to be replaced. You’ll need a 13mm socket on the bolt head and a 15mm on the nut. It should be easier to remove since no thread locker was used. Once the bolt is removed, ease out the torque arm. Now you will have a lot more room to remove the old bushing and install the new one.
The ‘standard’ DIY way to remove the old bushing is to use a hack saw blade. Before sawing you might want to put something to catch the bits of rubber that’s being sawed off so it doesn’t get scattered all over your engine. Having done that, insert the hack saw blade through one of the “gaps” in the bushing and start sawing off from inside out. Initially, you will be sawing of rubber and the feeling is soft. As you progress to about 1/8″ you will likely beginning cutting through the hard plastic part of the bushing. You’ll know this when the feeling gets harder.
This is the time slow down on aggressive sawing so that you don’t suddenly saw through the plastic and end up scratching the mount. When sawing, I suggest you use 2 hands to keep the hack saw blade level. Using 1 hand may cause you to saw at an angle and may scratch the mount. I guess no matter how you’re careful, you’ll invariably get the hack saw blade on the metal and make a tiny but insignificant scratch (I did). When you’ve sawed through the hard plastic, the bushing will collapse and it can be easily pulled off. Pull it off the mount from the driver’s side. Now the fun part. Insert the bushing into the mount from the driver side. Before inserting the new bushing, look for the arrows (alignment indicators) on the bushing. The bushing must be inserted so that the arrows are on the driver side and pointing up.
With the 2 pipe flanges, sandwich the mount and the bushing – you will instinctively know how to do this. Then run the 5″ bolt through the flanges/bushing coming from the driver side and put on the washers/nut on the other end (passenger side). Manually tighten the nut by hand until it is snug, then adjust & align the entire pressing tool. When everything looks ready to go, start tightening the nut to squeeze the bushing onto the mount. You’ll notice that on the first few turns the bushing may “slide out” on one side. If this happens, you may want to tighten the bolt slowly while centering the bushing with your other hand. When the bushing looks like it is evenly entering the mount, now is a good time to spray some WD-40 on the bushing. Then go ahead and keep tightening the bolt. In a matter of minutes, you should have most of the bushing already inside the mount.
If you are doing an S/V70, then you are probably done. However, if you are doing an 850 like me, you will notice that another 1/8″ of the bushing needs to be squeezed in – this is because the bushing is wider than the mount (in the S/V70 – the mount is larger than the bushing). This is where the ABS coupling comes in to act as a spacer. Disassemble the pressing tool. With the ABS coupling, use a hack saw to cut through the coupling (the faint line on top as shown in the picture). This will allow you to “expand” the coupling so it fits onto the mount from passenger side. Reassemble the pressing tool and do a few more turns on the nut to center the bushing on the mount. Take out everything and you’re done.
When you fit the new mount rotate the top forward about 15 degrees as this takes some of the ‘shear’ out of the thrust and the mount will last much longer. I still have an OEM mount in and it is about 6 years old.
I just did this last weekend, and I have a LOT to say…
1) I’d rather not second-guess the Volvo engineers. As an engineer, I know how complex interactions become; we can’t reasonably re-create their analysis. Better to replace it every couple years than have something shake apart, or lose your feet in a fender-bender. If you want longevity, keep your engine tuned and accelerate reasonably.
2) Specifics: a 1″ pipe flange fits around the mount’s protruding metal bushing/insert — no need for the mentioned ABS spacer. I used a piece of 7/16 all-thread — the largest that would fit inside — with 2 big washers (1 3/4″ dia., for 5/8″ bolts) on each end.
3) I tried and tried to get this to work, and finally concluded that the author had not actually done the procedure. The problem was that as I drew the press tight, one side or the other of the plastic mount would pop out. After a few attempts, the mount looked slightly disfigured, and I worried I would ruin it if I persevered.
3a) My first idea was to wrap a nylon wire-tie around the plastic to help it hold its shape as the press drew it in (a huge wire-tie — 3/8″ wide.) I put the end of the wire-tie in a vise and used a screwdriver to tighten it unimaginably. This still didn’t work because (it appeared) there was a weakness at the wire-tie clamp — the mount usually popped out there, and I couldn’t keep it in.
3b) I suspected that the mount was too free to misalign (not draw straight in), allowing an edge to pop out. I placed 5/8″ nuts as spacers inside the pipe clamps (between the washers and the mount bushing.) To help center them, I wrapped those nuts in electrical tape to take up the space between the nuts and the pipe flange.
3c) The final point is that I wedged a wrench into the left side (by resting it on the firewall), which freed my left hand thumb and forefinger to feel the plastic as I drew the press tight with my right hand (using a breaker bar!) If I felt the plastic expanding at the front of the car, I’d pull the left side toward the front (with the remaining play in my rig) to get it back in control. That actually worked. Once the mount was snug, I cut the wire-tie off.
A quick calculation says that this press developed approximately 50,000 pounds of pressure. And I don’t think I was “out of the woods” until the mount was 1/4″ seated. Still, while I spent several frustrated hours developing this procedure, it only took a few minutes once I had a working method. In retrospect, the original author may have relied on method 3c alone, which may suffice for smarter folk 😉