Grinding noise at idle

[bionick]

So I have a grinding noise. Happens mainly when I am not moving and just idling. What are all the possibilities? I know that since it happens with the car not moving, it limits the possibilities a bit. Don't know if it's maybe a part of my exhaust or what because I tightened it up good and it's still there. When we did my cam swap we accidentally dropped a retainer and it went somewhere in the engine bay and we could never find it. As far as I know it's still in there. But I don't see how the retainer could be as loud as it is. Sometimes you can notice the grind noise outside the car if you lay on the ground and stick your head down underneath but it is extremely noticeable inside the car. You can't hear a single thing with the car running and the hood up. Makes me think it is not the motor. It does seem like it's coming from the mid section of the car but I don't know. Any tips or suggestions would be great. Also, car is driving perfectly fine. No issues at all.

[dentnshell]

not moving / idling? with the clutch in?

Throw out bearing?

[nicholasp]

Reviving this old post as I am having a similar issue.

Seemingly out of nowhere as I had not done any work on the vehicle recently.

Sounds like a growling/grinding noise from under the vehicle, mainly audible only from inside the cab. Intermittent at idle, clutch position makes no difference. Audible also when driving but seems to be more noticeable under load.

There are no performance issues that I can notice at least. Any thoughts where to look?

[Mouse330]

Can u hear the noise engine running at idle? does it get louder or change when revving? There's a lot of things that could come into play. especially under load. If u can hear it with the engine running while not moving I would take the serpentine belt off start the engine and see if u still hear it.

[nicholasp]

I'll try that. The noise is most noticeable in the cab at idle, intermittently. I tightened the header bolts and that didn't change anything. It sounds like it is below me when I am sitting in the driver seat if that means anything.

[Joe.G]

There is a good chance your exhaust is rubbing somewhere, even a slight touch will send vibration and noise though the car.

[nicholasp]

I was thinking exhaust initially, but came up empty. I have American Racing long tube headers. Any specific points you would check?

[Joe.G]

Any where that it's close to the car, stock exhaust besides headers? You can run your hand around it and see if anything is hitting. Doesn't take much .

[nicholasp]

MBRP 3" dual after the headers, I'll get it on the lift this weekend and check it out!

[Joe.G]

Yeah check around the braces under the car I think that's your issue. Remember the exhaust moves with the motor.

[1JEWLDSSRS]

Yeah, if you have 3" exhaust the main rub point on my car was the trans tunnel brace, I had to install some washers between the floor and the brace for clearance, until I bought a BMR tunnel brace that gave it more clearance, also check your heat shield along the way, maybe it came lose, or is bent some along the trans tunnel. Good luck. Also check your headers for clearance along the frame around the engine compartment. Do you have 2" or 1 7/8 headers? The 2" sometimes hit the frame.

[ZMEnow]

Originally Posted by nicholasp

I'll try that. The noise is most noticeable in the cab at idle, intermittently. I tightened the header bolts and that didn't change anything. It sounds like it is below me when I am sitting in the driver seat if that means anything.

As the clutch wears the springs that hold the discs to the flywheel won’t be able to maintain the slack, so they rattle at idle. You could check if you have a cable scope camera by looking through the trans exhaust port.