I have a NASTY vibration of something at 1850 RPM's.
It sounds like a brake line banging up against the frame and making a motorboat noise.
I haven't been able to hunt it down yet because its only when the engine is under load and I'm not quite brave enough to put the engine under load at 1850 RPM's and then start crawling around under there.
Its reallly annoying because 1850 RPM's happens to be 35 MPH and 45 MPH so city driving is awful...The monsoon system cant even fix it!
Anybody had this and know what I should be looking for?

 

You might have dented something, like a driveline, or broken something like a mount. I would recommend you take it to the dealer to have them look it over and fix it.

 

I ditto Linus...Also check to see if your exhaust pipes are not misaligned too and banging against the underbody somewhere.

 

Have you tried a lower gear to see whether its excited by engine speed or wheel speed? If it's the exhaust banging on something all of a sudden, check you motor mounts too.

 

check the e brake cable under the driverside floor area . it has been noted to vibrate against the chassis . there is a bulitin on it

 

Its engine speed..not wheel speed.
I certianly would hope its not a dented driveline or broken mount. If it is, this will never survive off road since the worst abuse its had would be going over a manhole cover...
I'll check the e-brake cable..the other thing that came to mind was when I crawled under there for running wires for the backup lights, the clips that hold the brake lines (i assume is what it was..being the metal tube.) were not in place on the chassis. I also had the shifter motor replaced not long ago so I'm hoping its just another clip that did not get put back. I'll dig for vibrations after work. If nothing sticks out, I guess I'll take it to the dealer.......ugh...such a long drive.

 

Check the Air Filter Box.

When I installed the "True Flow" intake system, the air filter box was vibrating around the same RPM. This intake uses the stock box. The noise was very loud in the cabin.
The solution was to losen the intake hoses, push the air filter box toward the engine and re-tighten. This kept the box from hitting.

 

Not to bring up old threads but I FINALLY found the source of the noise.
It was more of a GROWL and less of a vibration. I could tell by the noise it was nothing as serious as anybody mentioned. Definately metal on metal vibration. And I could get it to do it while power braking so it was not anything with the drivetrain. The engine just needed to be under a decent load.

Turned out to be the passenger side engine heat shield vibrating against the block. I have a feeling the service guy leaned on it while changing the fluids or something and it bent it up against the engine. Just a little tug to get it away from the block and the nosie is gone!!!!

 

Glad it was that simple nothing major

 

Took him 30 days to get back with us though...tapping foot