XC90 Vibration at low RPM.

bigalbigal (@bigal) Tasmania
edited June 2016 in Troubleshooting
I just replaced a pile of mounts in my 2004 2.5T XC90 to fix an engine thrashing/thumping sound under hard acceleration. That issue has gone now which is great but now I have created another issue (small in comparison). I have vibration at idle and low rpm driving that wasn't there before.. it's not terrible but it's something that bugs me and mainly felt in my hands on the steering wheel.

I replaced the front and rear mounts, the one near the crank pulley, the trans torque mount and the upper torque mount. All rubber (definitely not poly).

Unsure what to try next. Sounds like this is fairly common.

The brands of my mounts are:

Top engine torque mount: Mackay (Rubber square bushing type)
Trans torque mount: Lemforder (Rubber, still seems a very very flimsy small bushing, bigger bushing looks good)
Front Engine mount: Trying to verify brand. Rubber.
Rear Engine mount: Same, trying to verify brand. Rubber.
Mount near crank pulley: Non genuine to save money, unsure of brand. Rubber.

Ideas? I'm determined to solve this.

Which mounts are most likely to cause vibration?

Comments

  • Ex850RSnoopy (@Ex850R) Somewhere Over the Rainbow. Melbourne.
    Saviing $ on mounts and suspension bushes etc usually means them not lasting a long time unfortunately.
  • I think I'll start experimenting with mounts by swapping back to some of the old ones one by one and see what affect it has, starting with the lower transmission mount.. I really don't like the look of that very weak small bushing in this part.. feels like I could easily break it with very little effort. My old one was a lot stronger.

    If and when I sus it out I'll let you know. Might help someone else.
  • Do mounts generally need time to settle and loosen up?
  • Ex850RSnoopy (@Ex850R) Somewhere Over the Rainbow. Melbourne.
    Unless it is one like a suspension arm mount bush that requires loading before tensioning I would know
    Torqued to spec may be a thing??
    I got all new on my v70t5 , poly for half and cannot tell when I replaced a shot main engine mount! Funny. Love the rumble though....
  • Do mounts generally need time to settle and loosen up?

    No
  • try and push or pull engine to see if vibration changes also check top engine mount small bush at firewall, move steering to different position and feel. it might not be a mount issue now but something too close causing a vibration.
  • The stock front engine mounts are hydraulic filled to eliminate vibrations. In my experience aftermarket solid front engine mounts will cause the vibration you describe. I only fit genuine front engine mounts now to avoid any customer complaints
  • Just changed the lower torque mount for my original which is a lot stronger at the smaller join and it has helped quite a lot. Not sure what is up with that crappy Lemforder lower torque mount I bought off ebay.. That small bushing looks crappy and cracked already. So that has sorted most of the vibration at idle.

    I also removed some air out of the tyres as I was experimenting with fuel economy with 36psi. That has helped the riding vibration felt through the steering.

    I'll see how it all goes driving it to work tomorrrow.
  • My xc90 running 19"s is running at 42psi cause weight and towing
    Anything under 37psi and the sidewalls roll badly in heavy cornering

    Ive got zero issues with harshness or vibration at any speed

    You should inspect the front spring mounts and the rear shock mounts for excessive wear

    When they go you can easily get lots of vibration in the cabin
  • @VolvoDeger Cheers for the tips. I'll see how she drives tomorrow. I'll check those things also. I did end up torquing up the rod bolt for the top engine mount with it in Reverse while my brother was in control of the brakes. I picked up that tip online. I didn't touch the rod bolt on the torque bar closest to the firewall. I removed the bar completely when working on the engine mounts.

    @Philia_Bear I have read in various places online about the problems with those spring mounts. What should I be looking for exactly? Just a flat well worn looking mount?
  • And would I be right in saying the 5cyl is naturally a bit lumpy/uneven at idle and is a bit of a challenge to dampen vibrations down? I've never come across such sensitivity with engine mounts.. but I've mainly been in the 4 cylinder and flat 6 world. The 5 is an unusual beast to me.
  • 5 cylinder engines normally very smooth in running as no opossing cylinders to each other
  • Hi guys,

    I know this is an old thread but thought I would ask since I'm experiencing the exact same issue on my car - 2006 xc90 2.5T. Changed the engine mounts (all 5 of them) with aftermarket ones :( and now I have some really annoying vibration at low RPM especially on the steering wheel. The ones that were taken out were pretty average with cracks on them but they were definitely smoother than these new ones. The suspension spring seats were also changed. My question is, did you ever find the offending mounts? I suspect its going to be the lower front and lower back that are too stiff??

    Cheers!

    Steve

  • Ex850RSnoopy (@Ex850R) Somewhere Over the Rainbow. Melbourne.

    If you used the cheapest they may well be broken already....

    If you put in plastic type ones then you get instant vibration.

    There's a reason OEMor made by OEM manufacturer are a price.

  • Thanks @Ex850R - how can you tell if they are the plastic type ones? They looked very "Rubbery" when I got them 🤔

  • Ex850RSnoopy (@Ex850R) Somewhere Over the Rainbow. Melbourne.

    I mean the many so called sport ones or race ones in many colours you pay a lot for and make it really annoying to drive due to vibration,some don't even last as long as cheap ones.


    Check them all again...

  • The brand name is BAPMIC? It pains me to type that but that's what in there now. Ever heard of them?

  • Ex850RSnoopy (@Ex850R) Somewhere Over the Rainbow. Melbourne.

    No...

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