Weird engine rocking/shaking?

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  • drevilkep
    Noobie
    • Oct 2008
    • 8

    #1

    Weird engine rocking/shaking?

    So I've noticed my new-to-me 189,000 mile iS has a weird vibration when I'm revving the engine or accelerating. At about 1800, 2500, and 3100 RPMs, the engine shakes slightly, but enough to rock the car a little and move the shifter. It's more of a rocking, rather than an outright vibration (though the engine does vibrate too). I don't think it's driveshaft related because it occurs when standing still, in neutral, as well as when accelerating. I was thinking motor mounts, but I did the test where you set the E-brake, let the clutch out, and watch for engine movement. The engine doesn't seem to move much or at all, so I'm not sure about the mounts. They aren't leaking or cracked at all. The car does seem to vibrate more than I would expect all all speeds and at idle. Any ideas?
  • tjts1
    E30 Mastermind
    • May 2007
    • 1851

    #2
    Engine mounts don't have to be leaking or cracked in order to be worn out. Usually only the passenger side mount is worn. It takes most of the wear because of the direction of the crank and its exposed to exhaust heat while the driver's side mount isn't.
    My worn out passenger side engine mount next to an new one.

    Comment

    • drevilkep
      Noobie
      • Oct 2008
      • 8

      #3
      Originally posted by tjts1
      Engine mounts don't have to be leaking or cracked in order to be worn out. Usually only the passenger side mount is worn. It takes most of the wear because of the direction of the crank and its exposed to exhaust heat while the driver's side mount isn't.
      My worn out passenger side engine mount next to an new one.
      Did you replace just the passenger side mount, or both? Did it make a difference? They are pricey so I don't want to blow $250 if it won't make a difference.

      Comment

      • txleadfoot
        Wrencher
        • Apr 2006
        • 208

        #4
        wow, that's crazy. it's sagged down...what 1/2"?

        Comment

        • kencopperwheat
          King of Kegstands
          • Oct 2003
          • 14396

          #5
          IE Urethane mounts are like $50 each. Might want to check out your tranny mounts too... OEM ones are pretty cheap.
          Originally posted by Gruelius
          and i do not know what bugg brakes are.

          Comment

          • ethirtydavid
            R3VLimited
            • Jan 2008
            • 2331

            #6
            You don't need to spend 250 on engine mounts, you can get a good pair for much cheaper. If you replace one - replace them both.

            Comment

            • drevilkep
              Noobie
              • Oct 2008
              • 8

              #7
              Originally posted by ethirtydavid
              You don't need to spend 250 on engine mounts, you can get a good pair for much cheaper. If you replace one - replace them both.
              Where are you looking? Best I've been able to find is $119 each from BMA parts. I'd rather not do a solid mount as this is my daily driver and I'd like to avoid extra vibrations.

              Comment

              • tjts1
                E30 Mastermind
                • May 2007
                • 1851

                #8
                Originally posted by drevilkep
                Did you replace just the passenger side mount, or both? Did it make a difference? They are pricey so I don't want to blow $250 if it won't make a difference.
                Just the passenger side mount. Check pelican parts. It was $90 when I got it. BMA is overpriced. Stay away from urathane mounts unless you enjoy noise, vibration and harshness. Before you buy a new mount make sure it isn't something else like vacuum leak, sticky injector or ignition problem.
                cheers
                Justin

                Comment

                • drevilkep
                  Noobie
                  • Oct 2008
                  • 8

                  #9
                  Originally posted by tjts1
                  Just the passenger side mount. Check pelican parts. It was $90 when I got it. BMA is overpriced. Stay away from urathane mounts unless you enjoy noise, vibration and harshness. Before you buy a new mount make sure it isn't something else like vacuum leak, sticky injector or ignition problem.
                  cheers
                  Justin
                  Yea, I just got done replacing every vacuum and coolant hose, along with both intake gaskets. The car run smoother now, for sure, but there is still a vibration that runs through the whole car at those RPM points. I checked the transmission mounts yesterday and they aren't torn or crushed, but they are soft so I ordered two. They are cheap and easy so I'll try those first. I was able to find OEM motor mounts at ECStuning.com for $93 each so maybe I'll buy one for the passenger side and see if that helps.

                  Comment

                  • ethirtydavid
                    R3VLimited
                    • Jan 2008
                    • 2331

                    #10
                    Here are some products you can take a look at:

                    Engine Parts and More for Your 1991 BMW 318IS at Reliably Low Prices. Fast Online Catalog. DIY-Easy. Your Choice of Quality. Full Manufacturer Warranty.


                    http://www.partsgeek.com/gbparts/199...ek+Google+Base

                    If it were me, I wouldn't get the cheapest ones but those from Autohaus Arizona seem like the best idea. IMO

                    good luck, beats spending 250 bucks for mounts that are not going to be raced. Those prices are insane..

                    Comment

                    • EN318isPDX
                      R3V Elite
                      • Oct 2007
                      • 4373

                      #11
                      I like my IE poly engine mounts, a lil stiffer but my car is quieter on the outside, shakes a lil on the inside but not enough to grind your teeth

                      Comment

                      • E30nate
                        E30 Enthusiast
                        • Oct 2007
                        • 1050

                        #12
                        i had IE poly mounts on my m42. the only complaint i had was right at redline the accelerator pedal vibrated a little bit. other than that they were just as quiet as the stock ones, with minimal vibrations.

                        Comment

                        • twright
                          Mod Crazy
                          • Sep 2008
                          • 705

                          #13
                          Just so everyone knows: The engine mounts from RockAuto have a really good price ($20). However, they are not oil filled. They are solid rubber.

                          What this means is: 1.) If you're looking for inexpensive oil-filled engine mounts, don't go to RockAuto.
                          2.) If you're looking for solid rubber engine mounts, RockAuto has some with a good price on them.

                          Comment

                          • Mike@PureMS
                            Forum Sponsor
                            • Oct 2006
                            • 221

                            #14
                            We've got a number of different mounts available.
                            Both E30 and E36 alternatives.
                            Feel free to email or call us for info.
                            Mike

                            www.purems.com |Temecula, CA | 866-397-5487

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