Rattle When I Let Off Gas / Throttle in Cj5

[jwarthin]

I just did an engine swap. I replaced the stock AMC 258 i6 / 4.2l with another remanufactured amc 258. After a couple hours running it, I noticed a bad rattle when I release the gas pedal going down the road. It seems to be getting worse. It happens when I let off the gas at a red light or turns. Sounds like the noise is coming from under my feet near the tranny. When I hit the gas the noise goes away. And it happens before I push in the clutch pedal. When I push the clutch in the noise stops. Any suggestions are really appreciated!

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[Torxhead]

I am thinking you are going to have to do some more research on that one. Maybe removing the cover on the hump so you can see and hear in the Transmission area. Check to see if this noise is in your new engine or outside of it. A loose driveshaft comes to mind, make sure the hubs are not locked. I once had a similar noise that turned out to be the flywheel rubbing against the cover.

 

[mtnwhlr]

Sounds like a bad U-Joint to me.

 

[jdcaples]

Can you remove the wheels, put the Jeep on jack stands to prevent it from rolling forward, and listen while you're outside, under the driver's seat?

Or is that just completely foolish? (he says having done this with vehicles on a hoist)

-Jon

 

[TUX IV]

put the Transfer Case in neutral and with the jeep sitting still, shift the Transmission through the gears using the clutch. If you still get the noise then you know it is from the transmission forward. If you don't hear the noise then it most likely is from the transfer case back assuming 2WD operation.

 

[Lumpy Grits]

:ww:
Check your manifold bolts and every other bolt you can put a tool to.
BTW-ck your skidplate for movement.
Tell us more about what all was done with the 'swap'.
LG