Hello there,

My 2005 Volvo S4o with 2.4i (manual) gets shaky from time to time, mostly noticeable at around 2.4K-2.6K RPM, though it may be axles, tho it also happens when the car is not moving, probably it's the engine, as the whole airbox shakes too, haven't checked for misfires yet but it doesn't seem like it would happen, will check with OBD tomorrow just to make sure (no check-engine light) I remember there was a thread somewhere about this issue related to bad or too strong rubber inside the engine mounts and those reflect vibrations to the body, it would be cool to know which one exactly to replace (if that's the case) as I'm on a tight budget right now, appreciate all the answers!

 

This is what the main motor mount looks like when split. You can removed it before purchasing a new one to make sure. It's the top mount on the passenger side. Also check the bottom mount. It's a bit harder to see as you have to crawl up under the engine and use a strong light to look for cracks in the rubber.