Unfortunately, it is rare I get to drive my SC faster then 70 miles per hour. When I do, I'm noticing a "pulsing" sound from either the engine or the tranny or the wheels or the exhaust. I took a video of it the other day while on a fairly open freeway. Any idea what this is? Again, it only occurs when I go above 70 MPH.

 

I'd check the ATF, tires, all wheel bearings, then drive shaft bearings/U-joints, in that order, and verify the diff has enough of good oil in it.

 

Sounds like a weekend project. At least the tires are new (about a week) so I can rule them out.

 

"At least the tires are new (about a week)..." Wait... new tires you say? Hmmm.... raise the car with tires dangling. Spin them, one at a time, as fast as you can by hand. Hold up a straight edge ruler real close, parallel to the tread and check for "out-of-roundness" and/or any bumps/bulges. You can have a tire balanced ok but still be out of round. Causes weird things..

 

I'll take it to my mechanic (since I'm not named, Tyler Hoover and don't have a lift at home) and let him take a look.

 

I believe the sound you hear is the same as the one i have experienced on a couple of sc400 that i have owned. I eliminated the noise by replacing the center drive shaft bearing.

 

You may spend all weekend trying to find this, however, the easiest solution will be to get that thing up on a lift, start spinning things, and that'll give a good trained eye a quick answer as to what's causing all of your noise. Best of luck!

 

Well, by coincidence, I was stuck in traffic behind a broken-down semi yesterday. Also the fan relay switch for my e-fans died, so my engine started overheating. I took the car into my mechanic to replace the relay.

While there, I had it on the lift and took a look. Neither of us found anything abnormal. He even drove it up to 90 MPH to see if he could replicate. Nothing at the moment.

I'll chalk it up to a gremlin and monitor it.

 

Fair enough! Glad you got it checked out.