Heavy Vibration at Idle (Smooth when put into Winter/Wet mode)

[RandyPants]

So, my 2007 is having some odd, HEAVY, slow vibrations/shaking (almost feels like an old school diesel tractor) at idle. Probably at 3-4 Hertz.

This happens in P, R & D. A bit less so in N. The tachometer is steady as a rock. It does sound like the slow vibration is just the motor movement itself. Doesn't seem like the rough idle of which I've read some issues (about the ETM failing, with the tach needle jumping around).

My car is a 2007 Volvo XC70, with 129,000 miles. Air filter is good. And spark plugs and timing belt are relatively new.

I've ordered a full set of Hutchinson motor mounts, including a new torque rod (while I'm at the mounts). Hoping it's as simple as that.

Oddly enough, though, the issue goes away the moment I put the transmission into "W" (Winter/Wet) mode. I just discovered this earlier today. Which now has me worrying the issue might be with the transmission.

Any help, guidance or input would be greatly appreciated.

[vtl]

What helped me is all new engine pads/mounts, subframe bushings and Hilton tune that brought idle revs to 800 like Volvo N/A (non-turbo) engine has. I hardly feel any vibration on the steering wheel.

3-4 Hertz you can't hear. What do you feel, an oscillating resonance with that peak to peak frequency?

[hoonk]

HEAVY, slow vibrations/shaking at idle.

I've ordered a full set of Hutchinson motor mounts, including a new torque rod

The most common failure is the mount on the front of the engine - on the right side. It breaks/sags/fails due to old age/oil drippage and transfers the vibration of the engine directly to the subframe. If it is the original mount - it is probably broken.

The hydraulic mount on the left (front of car) side of the engine fail/breaks/splits/leaks/sags and creates a vibration. Check for a stain on the subframe near the mount where the goo from the mount has leaked out. Accel in gear (with the brake on) and have an observer freak out how much the engine moves up if the mount is broken!

The mount on the right side/rear attached to the steering rack/subframe is a PIA to replace. I have never sold one of those.

The upper torque rod bushings are always broken - they don't create a vibration, but do make a rattling noise if they get bad enough, the lower torque rod bushing do go bad, but don't create a vibration, you might notice a increased "tightness" between accel and decel if you replace one or both the torque rod bushings.

I would look first at the front engine mount and save your money for other things that might (will) need to be replaced.

[RandyPants]

3-4 Hertz you can't hear. What do you feel, an oscillating resonance with that peak to peak frequency?

Apologies, that was me trying to mention the frequency of “shakes” coming through the car, per second.

[RandyPants]

The most common failure is the mount on the front of the engine - on the right side. It breaks/sags/fails due to old age/oil drippage and transfers the vibration of the engine directly to the subframe. If it is the original mount - it is probably broken.

The hydraulic mount on the left (front of car) side of the engine fail/breaks/splits/leaks/sags and creates a vibration. Check for a stain on the subframe near the mount where the goo from the mount has leaked out. Accel in gear (with the brake on) and have an observer freak out how much the engine moves up if the mount is broken!

The mount on the right side/rear attached to the steering rack/subframe is a PIA to replace. I have never sold one of those.

The upper torque rod bushings are always broken - they don't create a vibration, but do make a rattling noise if they get bad enough, the lower torque rod bushing do go bad, but don't create a vibration, you might notice a increased "tightness" between accel and decel if you replace one or both the torque rod bushings.

I would look first at the front engine mount and save your money for other things that might (will) need to be replaced.

Good to know, I’ll take a look! Thank you!

[Astro14]

I’ll second what Hoonk says. Right side mounts fail, especially with oil exposure. Start there.

Every Volvo I’ve ever owned has had short lived engine mounts. Seems to be their nature.

[RandyPants]

Thank you, so much. I'm glad I already ordered the hydraulic motor mounts as a part of the set.

[MacNoob]

Every Volvo I’ve ever owned has had short lived engine mounts. Seems to be their nature.

Swedish thing? All my Saabs burned up engine mounts too.

[Astro14]

Swedish thing? All my Saabs burned up engine mounts too.

I don't know.

I just assumed that Volvo engineered the engine to absorb crash energy by breaking loose and going under the car, and that this consideration put more stress on the mounts.

But that's a guess...