Chasing a vibration noise.

[Miker]

I have been chasing a vibration noise since I bought my 2005 Roush. It sounds like it is coming from the left rear high up. I thought I had found it 3 times. First time I found the left quarter panel louver to be loose when tapping on it. Took it off and went for a drive only to have the vibration show up again after a few miles. Second was the cover over the center light in the trunk. I removed it and at first no more vibration but it returned again after a few miles. Lastly I found that if i rapped on the inside plastic trim on the inside of the quarter window it would vibrate. So I shoved some closed cell rubber between the plastc trim and the glass and again it seemed to help at first only to return after a few miles.
So I have determined it is happening once the car gets up to operating temp and is probably related to the exhaust. It does appear to be high up on the drivers side and in the area of the trunk lid. I have hit the exahust with a rubber mallet and have not been able to recreate the sound although not when the car was hot. It seems to be most prevailant at around 2000 rpm but also happens when letting the clutch out from a dead stop as the rpms drop.
Please help if you have any ideas.

 

[JC SSP]

If you think its exhaust related, check all your hangers and grommets... Also, look for any rubbing on the pipes...

 

[moooosestang]

your exhaust will move a lot when it heats up. i had a hanger rubbing the metal mount, but you wouldn't know by looking at it. try wrapping something around the rear hangers.

 

[MrBhp]

Wasn't there a mid hanger on the early cars that caused this? Ford deleted it a year or two after production of the s197 began.

 

[Miker]

Wasn't there a mid hanger on the early cars that caused this? Ford deleted it a year or two after production of the s197 began.

I will check that. Mine is an early car.

 

[MrBhp]

I will check that. Mine is an early car.

It's mounted to the transmission crossmember, IIRC.

 

[Miker]

It's mounted to the transmission crossmember, IIRC.

Thank you!

 

[Miker]

So I may have found the culprit. I got the car up on stands and peered around. The engine and exhaust were cold. I found the forward exhaust mounts from the cross member and they seem solid. What I did find is that the exhaust hangers to the rear of the axel displayed a shiny area about 1/2 inch in front of the rubber in the hanger. Like the exhaust was somehow moving back or expanding after the axel 1/2 inch. It has a Roush exhaust and there is 1 hanger past the axel and 2 hangers for the muffler. The end of the rear hanger on the drivers side was about the same distance from the body. There were marks on the body that matched up with the end of the hanger. But the body was not shinny like it had been rubbing. It looked indented like the hanger was hit against it like a punch would dent steel when hit with a hammer. It almost looked burnt and the end of the hanger looked that way too. So I cut off about 1/2 inch of the hanger. The passenger side had over an inch of clearance. Hopefully this was the culprit. Going for a drive now to find out. Wish me luck!

 

[Miker]

That was it! I also had a squeak that is now gone. Amazing that the exhaust would move that much. Here are a few pics of what I cut off. Now looking at it I can see the rubbing had actually beveled the edge.