New strut needed or strut mount ?
 

Hello,
I have a 2002 s40 and about a week ago it started acting strange. When I go over a bump the passenger front seems to "float" or bounce. When I looked under the hood and push the front end up and down the strut bolt on the passenger side moves up and down and the drivers side does not. Can someone point me in the right direction here please ?

Thanks,
Nick

Spring seat.

My guess is the strut mount has broken. Normally these wear out causing a clunking sound over bumps. If yours has somehow failed completely with the rubber part of the mount broken, it could move exactly as you described.

The floating you describe has also been associated with a failed strut. Basically the damping no longer works and your car is floating on the strut spring alone with nothing to stop the occilation up and down. However, the nut on top of the strut should not be moving which is why my first guess is the mount.

That is what I thought , Is it possible to check the strut mount from the top of the car ? It is my first time diagnosing a strut problem.

Look at the nut on top of the strut. It should be centered in the strut tower hole. If it's off center then the rubber has worn out allowing the movement. Look for loose pieces of rubber too. There should not be any.

The center nut stays center and does not move sideways... what do you think ?

You got a couple hours and the tools? Take it apart and eyeball it. You will want a strut spring compressor, impact wrench, and breaker bar. The breaker bar helps break loose the two large nuts connecting the strut to the hub. A bit of heat always helps break any rust bonds also. The impact is used to spin the nut on the strut after the spring is compressed. You don't need to secure the shaft from turning as the impact spins the nut hard enough that inertia works in your favor.

With the right tools and experience you could have it apart in 30 minutes with coffee breaks. The down side is if you need the car right away. Then you have to stick it all back together until you order the parts. The upside is you only order what you actually need.