noise at 1200 RPM's (1 Viewer)

[Herky]

I have a '99 with 115k miles on it. The 100kl service was done 6k miles ago. It recently developed a noise that is noticable between 1200 and 1800 rpm while excelerating. It doesnt happen everytime. It sounds similar to a playing card being ticked by a low rpm fan kind of. I can't pin point the noise exactly but it sounds like it could be from behind the radio area or even around the transfer case lever. It isn't very loud but it's noticable. No other symptoms are present.

Any ideas on where to start looking? The AC controls don't seem to matter. You can have it on, off, auto, feet only, outside, recirculate, it doesn't matter. I've moved the transfer case into H, N, L and back to H with no luck either.

Help please!

 

[hoser]

Maybe a cracked exhaust manifold? Is the noise more prevalent on cold start-up?

 

[Herky]

I think I hear it more right after it starts up. I would think if it was a cracked manifold I could hear it even if I just revved the engine without having it in gear. No?

 

[Herky]

Does anyone think it could be coming from the transfer case? Heard a noise similar?

 

[Maniac]

I had a noise that I thought was coming from the transfer case at those same RPM's, it got worse with time. It would go away if I pushed the OverDrive switch to off. Ended up being a serious transmission probem, requiring complete replacement. I hope that's not the case with your situation.

 

[trainrech]

We just replaced the driver side exhaust manifold on our '00 w/ 80k. A distinct ticking sound tied directly to RPM, but not really noticeable at idle. Really noticeable when cold at lower end RPM's and/or under load.

 

[hoser]

I think I hear it more right after it starts up. I would think if it was a cracked manifold I could hear it even if I just revved the engine without having it in gear. No?

Yes, under load, the sound might be more pronounced. Open the hood on cold start-up and see if you can better locate the sound. I know it's cramped quarters down there though.

 

[Herky]

I listened for it this morning with the hood open and no luck.

Maniac. Did you encounter any other signs before you had to rebuild the transmission?

Anyother tell tale signs to look for on the exhaust side of things?

 

[hoser]

As for exhaust leaks, sometimes the noise goes away when the engine warms up--the heat expands the metal and stops the leak. An exhaust leak will also sometimes cause you to fail a smog check. The only sure way I know to detect leaks is a smoke machine where it pumps smoke into the exhaust pipe and you are able to see the smoke from the leak. I have no idea where you'd find this machine though. Maybe best to take it to the dealer.

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