Knocking sounds in dash

[amagedson]

This just started recently. I noticed a clicking/thumping noise deep in my center dash. 2001 tj with 4.0l. It's only when it's in drive and not moving. (foot all the way on the pedal) and it starts when i slow down to 10mph and bellow. It's pretty loud and i was wondering what it could be.

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[Chris]

It's only when it's in drive and not moving

That statement doesn't make sense. If you're in drive, doesn't that imply that you are moving?

Either way, it sounds like a drivetrain vibration. You say it's only under 10 mph? I'd start by inspecting the u-joints or the driveshaft for starters.

Does it happen at all when you're turning?

 

[amagedson]

That statement doesn't make sense. If you're in drive, doesn't that imply that you are moving?

Either way, it sounds like a drivetrain vibration. You say it's only under 10 mph? I'd start by inspecting the u-joints or the driveshaft for starters.

Does it happen at all when you're turning?

It's not stick. When im in drive and say at a stop light. I hear the sound, but when i drive off it fades.

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[JMT]

In that case, our TJ’s transmit a lot of vibes from the transmission to the tub in the 500-700 rpm idle range. The vibe damper is the transmission mount. If you have over 125,000 miles, it’s likely the mount needs to be replaced. If so, something else is rattling/clunking due to those vibes. Hard to say what that is. Sounds like you could get someone to sit in your Jeep in drive with the brake depressed and start hunting for it!

 

[TJ2]

Lift it and go under the drivetrain and shake all the shafts real hard, I suspect it is a worn mounting/mechanical assembly of some sort between the trans and the engine.

 

[Chris]

X2 to the above, especially @JMT's suggestion of replacing the transmission mount. If it only happens when you're idling, but not really when you're moving, that sure does sound like the transmission mount having gone bad and transmitting more vibrations into the cabin.

Sounds like textbook symptoms of a bad transmission mount to me.

 

[amagedson]

X2 to the above, especially @JMT's suggestion of replacing the transmission mount. If it only happens when you're idling, but not really when you're moving, that sure does sound like the transmission mount having gone bad and transmitting more vibrations into the cabin.

Sounds like textbook symptoms of a bad transmission mount to me.

We checked under the jeep and the mounts looked good. No movement. The rattling however can't be heard under nor inside the engine bay. It's just in the center of the dash

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[Chris]

Sometimes looking at a transmission mount isn't good enough, they can be bad even if they might look okay.

However, if you're 100% certain, I think that you may have something loose under the dash, just not sure what. Might be time to take off the dash!