Just replaced the rusted out exhaust (the new one is Bosal from cat back… fit wasn’t all that great) and don’t know if I’m picking up on a old vibration that I missed due to noise, a new vibration due to the exhaust or perhaps another influence.

It may be present at 1100 and 4400 as well, but it’s hard to tell.

It’s not “crazy” harsh, just noticeably louder than 100rpm lower or 100rpm higher.

Appreciate any suggestions.

 

I'm not familiar with Bosal products for R53 fitment but on mine, seems the natural engine resonance frequency is ~ 2500 +/- 200 rpms which will be felt/heard if any metal-to-metal contact or insufficient attenuation by the exhaust system used.

 

Did you replace the rubber hangers? Those things wear out too and tear. If it's a noise that was masked due to a noisy exhaust, then could be lots of things. My wife's car had loads of vibration issues due to a motor mount (hers has the hydraulic one that yours does not), but if you've never replaced the motor mounts, the bottom dog bone mount, and the top rear mount are ones that commonly have tears in the rubber that can lead to increased vibration. Some places to start looking anyhow.

 

Found the problem, the exhaust hangers mid-pipe are pulling the mounting bracket TIGHT against the bottom of the car. I took off the center plate (thus leaving the mounts hanging) and the car purrs like a kitten.

I’m thinking this would be a little hard on the flex joint for the long term, so measuring from the bottom of the car to the exhaust mount and I will need to bend down the mounting ears on the exhaust down by 9-10mm to center them in the mounts.

 

Wait? What?

Please explain where things were touching. I’ve replaced two engine mounts and the hangers you described twice but didn’t notice any static stress. I hope I missed what you found.

Is your still quiet?

Thanks,
Peter

 

I had to bend down the cross wire on the midpipe that goes through the mounts shown above as there was a good 6mm of tension. Once I centered the hanger in the mount all has been quiet (or quieter… all relative in a R53!)

 

Ugh. I took the mid pipe bracket loose and its happy spot was 6mm down so I put in 6mm of washers but it is still noisy. I then replaced the Dogbone motor mount at the bottom of the engine, but still noisy. I then pried the AC lines away from the front of the transmission (hitting after the car was totaled 15 years ago), but still noisy. Did I mention I also replaced the hydraulic motor mount twice as I thought I messed up the first one because I mis-tightened the long TORX bolt, but still noisy.

I’ve ordered a CVT transmission motor mount but it will take a week to arrive, so I’m on hold for that.

Peter