1995 3000GT VR-4: 3SX Polyurethane Motor Mounts Installation

• Why Do I Want To Do This?

  • The OEM motor mounts are made of rubber, and some of them are fluid-filled. This design allows for some movement of the engine when it is operating, and helps isolate the vibration of the engine from the chassis. Eventually, these rubber mounts deteriorate (crack, leak fluid, etc.) and will allow for much more engine movement. It also seems that hot/dry climates will deteriorate this rubber even more quickly. Launching or powershifting the car also puts a great deal of stress on the mounts. When you need to replace your motor mounts, you can either get new OEM mounts, or you can look to one of the aftermarket companies that makes different mounts. 3SX Performance sells mounts filled with a polyurethane compound, which is much harder ( and theoretically more durable) than the OEM rubber. The metal frames of the mounts are powder-coated for rust protection and aesthetics, too.




• How Often Should I Do This?

  • My OEM motor mounts lasted about 75,000 miles before the rear roll-stopper failed completely (see below), resulting in excessive engine vibration. My car spent the first 53,000 miles in Tucson, AZ, where it's quite hot and dry. I've heard of some people who have had mounts last over 120,000 miles, and some who have had them last under 50,000 miles. It all depends on your climate and how you use your car.
  • Note that a visual inspection of the mounts while they're installed in the car may not be enough to detect a mount that is cracked or leaking, but not yet missing pieces of rubber. Both my transaxle and front (roll stopper) mounts looked just fine on the car, but I found significant problems once I removed them from the car.




• How Long Will It Take Me To Do This?

  • If you're doing all 4 mounts and haven't done it before, plan on a whole weekend. You may be able to get them done in a day, but especially if your car has many miles on it, you may find it difficult to remove some of the parts.




• Anything I Should Do Prior To Attempting This Procedure?

  • Raise and support the car so that you have access to the underside of the engine.
  • Remove the passenger's side front wheel.




• What Mitsubishi Parts Will I Need?

  • None.




• What Other Parts Will I Need?

  • 3SX Polyurethane Motor Mounts




• Where Can I Get the Stuff To Do This?

  	Part	Company/Contact	Part Number
  	3SX Polyurethane Motor Mounts	3SX Performance	N/A





• What Tools May/Will I Need?

  • Floor Jack
  • Block of Wood
  • Cheater Bar
  • 1/2" Drive Socket Wrench
  • 3/8" Drive Socket Wrench
  • 1/2" Drive 9" Extension
  • 3/8" Drive 6" Extension
  • 1/2" Drive 3/8" Drive Adapter
  • 1/2 Drive Universal Joint
  • 3/8" Drive Universal Joint
  • 19mm 1/2" Drive Deep Socket
  • 17mm 3/8" Drive Deep Socket
  • 14mm 3/8" Drive Deep Socket
  • 12mm 3/8" Drive Deep Socket
  • 17mm 6-point Closed-end Wrench
  • 14mm 6-point Closed-end Wrench
  • 14mm 12-point Ratcheting Closed-end Wrench
  • 12mm 12-point Ratcheting Closed-end Wrench




• Erik's Review

  • Originally, I had planned on replacing my mounts with OEM mounts as I was concerned about excessive vibration being transmitted to my chassis. That was just a personal preference, not a reliability or performance issue. However, when I removed my rear mount and found it to be completely trashed, I had second thoughts about the decision to use OEM mounts. Upon realizing that I never, ever want to have to replace that rear mount again (it was a real pain to replace!), I decided to bite the bullet and put in the 3SX mounts.
  • Honestly, I was a bit worried when first drove the car with the 3SX mounts as there was a lot of vibration that I found annoying. However, after putting about 100 miles on the car, the vibration had lessened substantially. It seems that the mounts soften up a bit once they are broken in. As of now, the increased NVH (noise, vibration, and harshness) in the car is pretty minimal. I have no complaints.
  • As far as the improvement from the polyurethane mounts compared to my aging OEM mounts, the difference is substantial. The engine basically doesn't move. Ever. This gives shifting a more precise, solid feel and there's much less slop on accleration/braking transitions. All said and done, I give this modification 2 thumbs up - highly recommended.

The Procedure

	Clear Out Area Near Transaxle Mount
	You'll need to remove the battery, the washer fluid tank, and the support bracket for the washer fluid tank. If you don't remember how to do this, check out the Fuel Filter Page as it involves these same tasks.
	Support Transaxle
	Support the transaxle from underneath it so that there is no weight on the mount. I used a floor jack with a small block of wood on the transaxle case. If you're not sure when the mount is unloaded, have a friend watch the mount while you slowly jack it up, and when you first see the rubber and cross pin move, that's it.
	Break Cross Pin Bolt Free
	Fit a closed-end 17mm wrench on the forward-facing side and a 17mm socket on the rearward-facing end. You may find that a cheater bar is helpful here.
	Remove Cross Pin Bolt
	Don't loose the nut or lockwasher!
	Remove Mounting Bolts
	here are four 14mm bolts that secure the transaxle mount to the chassis. They are accessible via holes in the passenger's side wheel well after you remove the rubber plugs that cover the holes. Using an extension and a universal joint (upper left bolt), remove the bolts. On the last bolt, be careful to support the transaxle mount, because that will be the only thing holding it in the car. Note that it's much easier if you remove the passenger's side front wheel, even though I hadn't done this yet when the picture was taken.
	Remove Transaxle Mount
	That's it - it should be complete free now. Carefully remove it from the engine bay.
	Examine Old Mount
	Here's my old one - you can see it had several cracks in it, was missing a small chunk of rubber, and was leaking. Not particularly good, though it seemed to be able to do its job for the most part.
	Compare Old and New Mounts
	Make sure you've got the correct one. New OEM mount shown, but the 3SX mount should look basically the same, except for the material in the center will be polyurethane instead of rubber.
	Install New Transaxle Mount
	Don't forget to reinstall the rubber pads on the sides of the mount - the arrows on the pads point toward the engine. The new mount goes in the reverse manner as the old one came out. The only thing to be aware of is that you may have to fiddle with the jack height to get the cross-pin back into place, especially if your old mount was in bad shape. If you're installing the 3SX Polyurethane mounts, you may also need a pry bar to coax the engine to move to the correct position to get the cross pin back in. I found that loosening the four 14mm mounting bolts by 3-4 turns allowed some play in the mount that made it easier to line up the cross pins. The torque spec on the 14mm bolts on the mount bracket is 33 ft*lbs. The spec for the cross pin bolt nut is 51 ft*lbs. After you've got everything bolted up, lower the jack from under the transaxle and make sure everything's ok.
	Remove Radiator
	Amazingly, this is pretty easy to do on our cars. Remove the upper mounting brackets by removing the two black 12mm bolts on either side. Drain the radiator and disconnect the upper and lower radiator hoses by loosening the 10mm bolts on the clamps. Then disconnect the wiring harnesses for the fans. That's it - you can now just lift the radiator assembly out of the car.
	Remove and Replace Front Motor Mount
	With the radiator assembly out of the way, the front mount is right in front of you nose. There's a 14mm cross pin with a nut on one side - remove the cross pin. Then remove the three 14mm bolts that hold the mount to the front frame member. That's it - the mount is free to remove now. Note that if your mounts are in good shape, there should be basically no weight on the front and rear mounts when the engine is at rest. No jacking or prying necessary. Note that my old mount (top) had the rubber completely separated from the mount frame. It was still held in there by the engine bracket, but the rubber was shot. The new mount goes in just like the old one came out. The torque spec on the cross pin bolt is 36-43 ft*lbs, and the spec for the mounting bolts is 43-51 ft*lbs.
	Remove Rear Motor Mount
	Ok, this one is the big giant pain in the butt. If you can get this one done, the others will be a walk in the park. It was almost impossible to get a camera into some of the spaces you have to work with, so I'll give a verbal description for most of it. Remove the downpipe - see the Stillen Downpipe page if you don't remember how. Now, remove the heat shield from the rear turbo. This is not very fun. There are numerous 12mm bolts in very inaccessible places. I found that a ratcheting-type 12mm wrench was almost a necessity. Once the shield is free, you may find that by bending the lower part of it (accessible from under the car), you can more easily pull it out from above. Now, you need to unbolt the rear oxygen sensor housing. This is also a very large pain, but not quite as bad as the heat shield. You have to loosen the 14mm bolts on the turbine housing and then get the 12mm bolt on the support bracket near the downpipe connection. You may find that removing the oxygen sensor may help with accessing the bolts. I also removed the EGR pipe completely (12mm bolts). At this point, the factory service manual says you can remove the oxygen sensor housing from the car, but I couldn't figure out how to get it out. It turns out that you don't need to completely remove it to get the mount out - just move it out of the way. At this point, you can access all of the bolts for the rear motor mount, but I wasn't able to get the mount out. What I ended up doing is removing the rear turbo's wastegate actuator (one cotter pin and two 12mm bolts) to get some extra clearance. I also disconnected both of the heater hoses from the engine to get some more room, but you may not need to do that. The bolt for the cross pin is accessible from above, reaching through where the battery was. The nut on the other side is accessible from below if you have small hands or long fingers. For the four 14mm bolts that hold the rear mount to the frame member, I used a combination of extensions, universal joints, a wrench, a socket, and a cheater bar to get at them. See above-pictured contraption. That actually worked really well, especially with a helper hanging out below then engine to guide the socket into place as I fed it in from the top. To get the mount out, first rotate it so that the flat part of the mount is parallel to the firewall. Then slide the whole thing up to clear the motor mount bracket. At this point, rotate it toward you and maneuver it through the mess of wires and hoses to get it out.
	Compare Old and New Mounts
	Shown are 3SX (blue), new OEM (center), and old OEM (pieces missing). So here is the source of my odd vibrations when driving the car. My rear motor mount was so beyond dead that the cross pin wasn't even attached to the mount anymore. It was free to move about in there as it wished. All of the rubber pieces in there are pretty much free as well. That is not a happy mount.
	Install New Rear Mount
	Just like the old one came out. Don't forget to reinstall the heat shield (black helmet- looking thing) so that the rear turbo doesn't cook your new mount. The torque spec on the cross pin bolt is 36-43 ft*lbs, and the spec for the mounting bolts is 33 ft*lbs. Reinstall all of the exhaust components you removed and button everything back up.
	Replace Driver's Side Engine Mount
	This one is pretty easy. Support the engine so that there is no weight on the mount. This can be done by using a block of wood under the oil pan if you're careful. Once there is no weight on the mount, remove the three 17mm nuts that attach the mount to the engine. Then remove the cross pin nut on the rear side by using a 17mm closed-end wrench. You may find that unbolting the cruise control box gives you better clearance. The cross pin bolt is held in place by two 14mm nuts on the front side - you may want to remove the intercooler hose to get better access to these nuts. Once the cross pin bolt is out, the mount just slides upward and out of the engine bay. The new mount goes right back in the way the old one came out. The torque spec on the 17mm nuts on the mount bracket is 72-87 ft*lbs. The spec for the cross pin bolt nut is 51 ft*lbs, and the spec for the 14mm cross pin bolt nuts is 25 ft*lbs. Also, don't forget the rubber pads that go on the sides of the mount; the arrows point away from the engine for this one.