So, after my header install, there has been the usual vibration that we all know and live with, but when the car starts heating up, there is a rattle from under the passenger side of the engine. I've read several "rattling, vibrating" threads, but none were quite like this. The rattle always stops when I go beyond 1,000 RPM's, and only happens in Drive. Sometimes you hear it a little bit in nuetral when sitting in traffic, but it is usually quieter or won't happen as long. It kind of sounds like a jackhammer or a jig-saw. When the engine is real hot, it gets louder, especially when I try to parallell park after a long drive.

I've been running hot lately for unknown reasons, but I have a few ideas. a flush and 160* thermo should help, but I doubt the rattling will.

From what I've read, and what I know, I have the following ideas: Transmission cooling line vibrating against headers, motor mount bolt loose, heat sheild loose, alternator shaking (speed shop didn't re-install one of the rear braces that mount to the rest of the engine for reasons unknown). Keep in mind that because this only happens in drive, I cannot go inspect it while it is happening, unless I want to look under the hood while the car is moving , and everytime I try to get someone at my house to help me put the brake on while it is in drive so I can inspect, but it never gets hot enough or no one is around.

Since it only happens in drive, does that single it out as a transmission issue?

 

not really, this loads the entire drivetrain
does it do it in drive with your foot on the brake(not moving)? if yes, have someone else put it in drive, while you look for the rattle, concentrate on heatsheilds and trans lines