[Guest]

Hey guys, My 1996 Rav4 makes a loud vibrating noise at 4000 RPM. it is always the same RPM and the vibration then goes away but the pitch of the engine is very different after that. After 4000 RPM it is much more like an out of control cheese grater than anything else. Could this be a harmonic in some loose piece of metal somwhere in the exaust causing crazy vibration? I am pretty sure it is not comming fron under the hood as when I rev the car with the hood opened and i am looking under the hood, the noise seems to come from farther back. the initial noise at 4000 rpm sounds alot like when you take a piece of sheet metal and shake it, but much faster.

 

[Jeff]

A common problem, especially with older Ravs, is the heat shield on the exhaust pipe under the engine. It's not something you really need, so if it's rusted and loose, you can take it off.

 

[Guest]

Can you show me a picture? Is it the shield over the exaust manifold witht he picture of a hand with a slash through it?

 

[bmorton]

Sounds like he's talking about a heat shield that's underneath the engine, not the one in the engine bay that you see when you open the hood, with the picture of the hand on it.

 

[Jeff]

Yes it's the heat shield on the exhaust pipe under the engine. You will have to slide under the front of the car to see it. The exhaust pipe starts at the header in front of the engine (under that other shield you mentioned) and runs down under the engine towards the back of the car.

 

[Guest]

An extra hand will help a lot. have someone tap the tailpipe while you crawl undrneath the car...either heatshield or maybe some loose particle from your catalytic converter trapped in your muffler.

Goodluck.

 

[Guest]

ugh, kill me now, or do it for me, sigh, thanks guys.

 

[Jeff]

It's a lot easier to fix than it sounds. If you want to do it the easy way, just take off the shield and drive around to see if the car still makes the noise.