Hi I have a 2008 Fusion SEL AWD that my son drives. We bought it used about a year ago and it needed work but we got it for a great deal. At least we thought we did. When we test drove it the car sounded like the suspension was falling off every little bump so we may have missed this problem we have now. It has a Vibration/Noise between 30 and 38 MPH when under load. I know 38 sounds pretty specific but when I drive the car it happens less frequently than when my son drives. He drives slower than I do.
The car has brand new front struts and stabilizer bar links. New Rear shocks, New rotors and Pads all around. New tires and an alignment. And lastly new right rear lower control arm forward bushing.
My other son has a 2012 Fusion AWD that was making a slight vibration and it turned out to be the Rear Driveshaft. We also had the PTU drained and filled and about 10,00 miles in the last year no issues. (Knock on wood!!)
Yesterday I jacked the 2008 up, put it on Jack stands and removed the rear driveshaft. It doesn't seem to have any of the joints really locked up like the 2012 did. There is some play in the Carrier Bearing but not a ton.
Other thing that is now fun (NOT) was the nuts for the Carrier Bearing Mount were pretty rusty. I sprayed Penetrating oil on them before removing the other bolts. After removing the other bolts I sprayed more oil and tried ever so lightly to tighten the bolt. I have been wrenching for 35 years so tightening a little first is usually good practice. Not this time. As I said a little pressure and snap. First one is snapped off. I grabbed my map gas torch and heated up the second nut. Again I tightened first and it moved about a couple mm. I switched to loosen and get the same movement. Then tightened again and Snap. Both bolts snapped off. I think the last person to put a driveshaft in may have used an impact gun and way over-tightened.
So I need to figure out how to correct this but I need to find out if the driveshaft was all or some of the vibration. So I pulled the AWD fuse and took the car for a drive. I went on the roads where I can sometimes hear the noise and there was nothing. I was cautiously optimistic. My son got home from school and went to the gym. When he got back he told me that the noise was still there. I had him take me for a drive and sure enough it is still there.
I have made an appointment for the PTU and the Rear Differential to be drained and re-filled. But not confidant that these are the cause of the noise. If it is the PTU would it still be vibrating or making the noise without the rear driveshaft? Could it be a bad wheel bearing? If it is the PTU making this noise/vibration is it too late and it needs to be replaced?
I have taken the car into an empty parking lot and gone pretty hard in circles and figure 8's to see if the bearings make any noise or if the rumbling noise can be heard. Nothing that I can hear. But I am not driving over 30 while doing this.
I know diagnosing over the internet doesn't work so well so I am just looking to pick your brains and maybe see if anyone else has experienced this. I did do searches for Vibration, rumble strips and noise while under load and didn't see anything that quite fit this situation.
Does anyone have a similar experience or any insight/ideas on what this could be?
Also any ideas on fixing the broken carrier bearing studs?
I have seen some drill and tap ideas and some find the bolt from the top. Which could require cutting thru the floor, Then cutting the welds and then welding in a new bolt.
Thanks for any and all answers or ideas!
Mike
